WO2012081259A1

WO2012081259A1 - Method for manufacturing sake-arabushi and sake-kezuribushi

Info

Publication number: WO2012081259A1
Application number: PCT/JP2011/007042
Authority: WO
Inventors: Nozomu Oginome; Tatsuhito Yoshioka; Tsuneo Ito
Original assignee: Ninben Co., Ltd.
Priority date: 2010-12-16
Filing date: 2011-12-16
Publication date: 2012-06-21
Also published as: JP2013545436A; JP5774107B2

Abstract

A method for manufacturing sake-arabushi or sake-kezuribushi is disclosed. The method includes the steps of: (a) pretreatment, in which a salmon is cut up so as to make a fillet having skin, (b) soaking-in-water, in which a fillet having skin is soaked for 5 minutes-30 minutes in clean water or in water containing salt of 5% or less by weight and that is at a temperature of 20 deg C or less, (c) shajuku, in which the fillet is put into water having a temperature of 60 deg C-80 deg C and is maintained therein for 5 minutes-20 minutes, after which the water is heated so that its temperature increases and the fillet reaches a temperature of 84 deg C or more but less than 90 deg C within 30 minutes-60 minutes after the start of heating to increase the temperature of the water, and (d) smoking-and-drying, which includes at least six heating steps at an ambient temperature of 56 deg C-85 deg C.

Description

METHOD FOR MANUFACTURING SAKE-ARABUSHI AND SAKE-KEZURIBUSHI

The present invention relates to a method for manufacturing sake-arabushi (salmon denatured in hot water and smoke-dried without molding) and sake-kezuribushi (slices of sake-arabushi), and particularly relates to a method for manufacturing sake-arabushi on which molding is not performed, and sake-kezuribushi in which both female salmon during the period of egg collection or spawning and male salmon during the period of ejaculation can be used as raw materials.

Gyobushi, a type of dried fish obtained by denaturing in hot water and smoking-and-drying --- which is represented by katsuo-bushi (bonito denatured in hot water and smoke-dried with or without molding), and includes other types of dried fish, such as saba-bushi (mackerel denatured in hot water and smoke-dried with or without molding), maguro-bushi (tuna denatured in hot water and smoke-dried with or without molding), iwashi-bushi (sardine denatured in hot water and smoke-dried with or without molding), and aji-bushi (jack mackerel denatured in hot water and smoke-dried with or without molding) --- has been used as dashi stock and as a food by Japanese people from ancient times (see Patent Documents 1-3). However, because of worldwide overexploitation (overfishing), the need to set fishing limits has been discussed regarding many fishes, including tuna and bonito, and therefore the need for using a variety of fishes other than bonito as a material for gyobushi has increased significantly. In contrast, salmon, to which the present invention is directed, hatch in a river. Juvenile salmon instinctively go to the ocean and stay there for a few years, where they feed and grow to become mature salmon, after which they return to the river in which they had been hatched. Accordingly, by using this behavior of salmon, a fish-farming technology has been developed to increase the number of returning salmon by raising and releasing juvenile salmon that have been hatched artificially, whereby the catch of salmon has become stable. However, the salmon that go upstream to the stream where they were born cease to feed for some time while going upstream until they spawn, and it is said that they dissolve the protein of their muscles to obtain energy. Both the male and female salmon die within a couple of weeks after the female salmon lay eggs and the male salmon fertilize them. Salmon that have spawned, which are called "hocchare" in Japanese, are not palatable, and therefore only some of them are used as fertilizer or animal feed. Therefore, further effective use of such salmon has been sought. Some ideas for using such salmon have been presented as follows: preparing processed foodstuffs in which ground salmon flesh is mixed with minced chicken meat and ground pork containing pork fat to which seasonings and spices are added (see, e.g., Patent Document 4); smoked and dried salmon to which a proteolytic enzyme has been added so that the salmon become tasty (see, e.g., Patent Document 5 and Non-Patent Document 1); sake-bushi (dried salmon), which is produced by repeated smoking and drying for 1 hour at 90 degrees Celsius (hereinafter "deg C"), accompanied by aging at a normal temperature and a subsequent ripening period (see, e.g., Patent Document 1). However, those ideas have not yet been widely used.

Japanese Published Unexamined Patent Application No. 2004-105034 Japanese Published Unexamined Patent Application No. 2006-187212 Japanese Published Unexamined Patent Application No. 2005-058003 Japanese Published Unexamined Patent Application No. H05-161476 Japanese Published Unexamined Patent Application No. H09-271316

Shigeru Abe, Kiyoshi Oba; Food Science and Technology Research, Vol. 45, No. 7, pp. 391-397, 1988.

The objectives of the present invention are to provide a method for manufacturing sake-arabushi that is sufficiently palatable, to provide a method for manufacturing sake-kezuribushi using such sake-arabushi, and to provide a method that effectively utilizes uses as materials of sake-arabushi (1) mature salmon that have not gone upstream, (2) female salmon going upstream during the period of egg collection or spawning, and (3) male salmon going upstream during the period of ejaculation.

In order to achieve the above objectives, the method for manufacturing sake-arabushi that uses more than one type of salmon selected from salmon that have not gone upstream, female salmon going upstream during the period of egg collection or spawning, and male salmon going upstream during the period of ejaculation includes:
a pretreatment process in which the salmon is cut so as to make a fillet that includes the skin (hereinafter, both a fillet that includes the skin and a fillet without the skin are referred to as "fillet");
a soaking-in-water treatment in which a fillet, after pretreatment, is soaked in clean water or water that contains salt of 5% or less by weight, and that is 20 deg C or less but above the temperature at which water freezes; the fillet is maintained in the water for 5 minutes-30 minutes (hereinafter, in the soaking-in-water treatment, clean water or water containing salt of 5% or less by weight is called simply "water" unless stated otherwise);
shajuku (soaking-and-denaturing-in-hot-water process), in which the fillet, after the soaking-in-water treatment, is maintained in water of 60 deg C-80 deg C for 5 minutes-20 minutes, and then the water in which the fillet is soaked is heated until the temperature of the fillet reaches 84 deg C but less than 90 deg C, for 30 minutes-60 minutes after the heating is started; and
a smoking-and-drying process that includes: a first heating step called "ichibanbi," in which, the fillet, after shajuku, is and dried for 1 hour-9 hours at an ambient temperature of 80 deg C-85 deg C; a second heating step called "nibanbi," in which the fillet, after aging at a normal temperature subsequent to the first heating step, is smoked and dried for 1 hour-9 hours at an ambient temperature of 80 deg C-85 deg C; a third heating step called "sanbanbi," in which the fillet, after aging at a normal temperature subsequent to the second heating step, is smoked and dried for 1 hour-9 hours at an ambient temperature of 65 deg C-70 deg C; a fourth heating step called "yonbanbi," in which the fillet, after aging at a normal temperature subsequent to the third heating step, is smoked and dried for 1 hour-9 hours at an ambient temperature of 60 deg C-65 deg C; a fifth heating step called "gobanbi," in which the fillet, after aging at a normal temperature subsequent to the fourth heating step, is smoked and dried for 1 hour-9 hours at an ambient temperature of 56 deg C-65 deg C; and a sixth heating step called "rokubanbi," in which the fillet, after aging at a normal temperature subsequent to the fifth heating step, is smoked and dried for the same amount of time and at the same temperatures as in the fifth step.
Also, in order to achieve the above objectives, the method for manufacturing sake-kezuribushi according to the present invention uses as raw materials sake-arabushi manufactured by the above method.

The method for manufacturing sake-arabushi and sake-kezuribushi according to the present invention is capable of using as raw materials both female salmon during the period of egg collection or spawning and male salmon during the period of ejaculation, so that salmon resources can be effectively used, and so that sufficiently palatable sake-arabushi and sake-kezuribushi can be obtained. Also, the sake-arabushi and sake-kezuribushi obtained by the present invention is capable of preventing, for a long time, the generation of an unpleasant eye-irritating odor that otherwise would be generated and strengthened over time.

The best mode for implementing the method for manufacturing sake-arabushi and sake-kezuribushi according to the present invention will be explained in detail below. In the present invention, sake-arabushi uses salmon as its raw materials, just like traditional katsuo-arabushi (bonito denatured in hot water and smoke-dried without molding). Katsuo-bushi, which is a traditional Japanese preserved food, is made in such a way that bonito is boiled and then smoked with or without molding. Katsuo-arabushi is one type of katsuo-bushi but differs from katsuo-kabitukebushi (bonito denatured in hot water and smoke-dried with molding) which also uses bonito as its raw materials. Also, in the present invention, sake-kezuribushi is slices of sake-arabushi made so that the slices have a thickness of 5 mm or less, and generally under 3 mm. Incidentally, sake-kabitukebushi (with molding) or sake-kezuribushi made by slicing sake-kabitukebushi is not the focus of the present invention.

The salmon used as raw materials for this embodiment is from one or more species from the following: Salmonidae, Genus Oncorhynchus, or Genus Salmo. The species generally referred to as trout also are in the Genus Oncorhynchus, and can be used as raw materials for sake-arabushi and sake-kezuribushi. The salmon include, e.g., pink salmon (O. gorbuscha), chum salmon (O. keta), red salmon ( O. nerka), cherry salmon (O. masou), silver salmon (O. kisutch), king salmon (O. tschawytscha), red-spotted masu salmon (O. masou ishikawae), biwa salmon (O. masou rhodurus), rainbow trout (O. mykiss), Atlantic salmon (O. salar), and brown trout (S. trutta).

Raw salmon meat generally contains more lipids (fats) and is more tender than raw bonito meat. Sake-arabushi that is made from raw salmon meat having much lipids contains a high level of lipids unless a particular defatting treatment is performed. This means that sake-arabushi having, e.g., a lipid content of 10% by weight (equivalent to a moisture content of 15% by weight) tends to become a powder due to vibrations when being manufactured or transported, and it tends to deteriorate in flavor quality due to its oxidation caused by its contact with air. Also, if a defatting treatment like press-defatting is performed on sake-arabushi, the salmon, whose meat is relatively soft by nature, cracks during that treatment, or the meat does not become firm after smoking-and-drying, whereby good-quality sake-arabushi might not be obtained. In view of the above, in the present invention's method for manufacturing sake-arabushi and sake-kezuribushi it is preferable to use as raw materials salmon having a low-level lipids content.

While salmon are residing in coastal waters and preparing to go upstream to their natal stream for spawning or ejaculation, they mature sexually and their metabolic system changes. The nuptial color comes out in chum salmon or silver salmon (scattered spots or a striped pattern also develop in addition to the color change), the salmon's back projects or in some male salmon the snout becomes curved, and the level of lipid content in a salmon's living body begins to decrease. Furthermore, in this embodiment, salmon can include both wild salmon and salmon that were raised and released and that then return to their natal stream. As salmon go upstream, the level of lipid content in a salmon's body further decreases. In view of the level of lipids content in a salmon's body, using as raw materials salmon before they go upstream, salmon that are in the process of going upstream, or salmon whose metabolic system has changed after they have returned to their natal stream is advantageous in this embodiment's method for manufacturing sake-arabushi or sake-kezuribushi. Also, it is further advantageous to use female salmon in the period of before-or-after egg collection or spawning, or male salmon in the period of before-or-after ejaculation after they have returned to their natal stream, and it is more advantageous to use female salmon in the period of after-egg collection or spawning, or male salmon in the period of after-ejaculation after they have returned to their natal stream.

In this embodiment, it is preferable to use as raw materials species of Genus Oncorhynchus rather than those of Genus Salmo. Among species of Genus Oncorhynchus, it is more preferable to use pink salmon, chum salmon, red salmon, cherry salmon, silver salmon, king salmon, and/or rainbow trout, and it is even more preferable to use pink salmon, chum salmon, red salmon, cherry salmon, silver salmon, and/or rainbow trout. Also, as the content (%) of lipids as raw materials in raw salmon meat, 10% or less by weight is preferable, 7% or less by weight is more preferable, 4% or less by weight is even more preferable, and 3% or less by weight is most preferable. The lower limit of content (%) of lipids is not limited to the above amounts, because they vary among fish species. However, among chum salmon (O. keta), for example, which generally has a low content (%) of lipids, some have a lipids content (%) in muscle of 1% by weight before-or-after egg collection or spawning or before-or-after ejaculation after they have returned to their natal stream, and therefore the lower limit of the content (%) of lipid of salmon used as raw materials in this embodiment usually would be 0.5% by weight.

In this embodiment's method for manufacturing sake-arabushi, sake-arabushi is manufactured by performing the following processes sequentially: pretreatment; soaking-in-water; skinning; shajuku; and smoking-and-drying. Each of these processes will be explained in detail below.

(1) Pretreatment process
The pretreatment process is a process in which salmon that has been caught and is to be used as raw materials is cut so as to make fillets. If the salmon has been frozen, it is unfrozen and washed with water. The method of unfreezing representatively includes, but is not limited to, soaking in water or being sprinkled with water, which is preferable because such a method is economical and also does not hurt the taste of the finished products. During unfreezing, it is preferable that the belly of the salmon is cut open and its internal organs removed at about the time when the inside of the salmon body is not completely unfrozen. The head of a salmon is often cut off before the salmon is frozen. However, if a salmon has a head, first the head is cut off; then the meat inside the abdomen, the internal organs, and the dorsal fin are removed; and then the salmon is filleted. If the salmon used as raw materials has not been frozen, it is washed with water; the head is cut off; the belly is cut open; the abdominal meat, internal organs, and dorsal fin are removed; and then the salmon is filleted. Here, the fillets are the two sides of salmon that are cut away from the salmon's spine, or are the four blocks obtained by halving those two (dorsal and abdominal) sides. Because salmon meat is tender and tends to crumble or crack, the salmon is not skinned during the pretreatment process. If the above sequential processing steps are not performed as one continuous operation, the salmon being processed must be temporarily put into cold storage or frozen with the salmon as is. Also, it is preferable that fillets on which the pretreatment is performed are temporarily put into cold storage or frozen before the soaking-in-water treatment is applied to them.

A female salmon whose belly has been cut open and from which the eggs have been collected (the ovaries have been removed) but whose head has not been cut off is referred to as "semi-dressed," and such a salmon whose head has been cut off is referred to as "dressed" salmon. As for the standard yield (% by weight) in this pretreatment of female salmon, if the standard yield of a semi-dressed salmon is considered to be 100%, then the standard yield of a dressed salmon is 77%, and the standard yield of a fillet is 50%. If the standard yield of dressed salmon is considered to be 100%, then the standard yield of a fillet is 65%.
Male salmon are also generally pretreated in this way so as to make dressed salmon, from which the head has been cut off and whose belly has been cut open.
A male salmon from which the head has been cut off and whose belly has been cut open is also generally pretreated in this way so as to make dressed salmon, although male salmon don't have ovaries to be removed. In this pretreatment of the male salmon, if the standard yield (% by weight) of a dressed salmon is considered to be 100%, the standard yield of a fillet is 75%.

(2) Soaking-in-water process
The soaking-in-water process is a process in which fillets obtained by pretreatment are soaked in water. This treatment is intended to prevent the above-mentioned unpleasant odor that might be generated from sake-arabushi or sake-kezuribushi as finished products.

Water whose salt concentration equivalent to sodium-chloride concentration is 5% or less by weight should be the water used for the soaking-in-water. Such water can include, but is not limited to, tap water, well water, mineral water, deionized water, seawater, saline solution, or water combining two or more such water types. In addition, seawater can be deep-ocean water or desalted deep-ocean water if its salt concentration is 5% or less by weight. Although tap water or well water also contains a trace amount of salt, those types of water along with deionized water, distilled water, water purified by a reverse-osmotic method and so on, whose salt concentration is almost zero, are particularly called "clean water" in some instances in this Specification. If water whose salt concentration is more than 5% by weight is used, salt remains in the sake-arabushi or sake-kezuribushi obtained in the subsequent processes, and therefore the flavor quality might deteriorate. It is preferable that water whose salt concentration is 4% or less by weight is used, and it is more preferable that water whose salt concentration is 3% or less by weight is used.

Such water is used at temperatures of 20 deg C or less but above the temperature at which water freezes. This range of water temperatures to be used relates to the conditions --- such the amount of time for which the fillets are in contact with the water, the volume of water in which the fillets are soaked, and the water currents in which the fillets are exposed --- of the water in which the fillets are soaked. If the temperature of the water exceeds 20 deg C, the fillets might lose their freshness, or the factors such as glutamic acid and inosinic acid that determine the umami composition of the fillets might flow out during the process, or other unsalted soluble-solids contents (extracts) might flow out during the process, and therefore the flavor of sake-arabushi or sake-kezuribushi obtained in the subsequent processes might deteriorate. In order to avoid such problems, it is preferable that the temperature of the water be 8 deg C or less. The loss of freshness or deterioration of flavor quality in the fillets might cause the properties of the finished products of sake-arabushi or sake-kezuribushi to deteriorate, causing such undesirable consequences as a fishy odor, insufficiency of umami, or a decrease in resilience.

The lower limit of the water temperature is the lowest temperature at which water does not freeze. However, such a temperature cannot be determined in and of itself because it depends on the salt concentration, the trace amounts of soluble components in the water, and how the water flows or moves, and therefore the temperature might fall below zero. It is preferable that the lower limit of the water temperature be -1 deg C or higher, so that the fillets do not freeze when they are soaked in the water. In the actual operation, crushed ice made of fresh water or sherbet-like cold sea water that includes ice might be used without the need to use a temperature-control device equipped with a refrigerating machine. In such a case, the temperature of the water used for the soaking-in-water should be 0 deg C or higher.

Sake-arabushi or sake-kezuribushi obtained in the subsequent processes might immediately subsequent to its manufacture or over time after manufacture emit an unpleasant odor (different from the odor of spoilage or the odor of ammonia) that slightly irritates one's eyes or nostrils. This odor can be caused by the soaking-in-water conditions or in a subsequent process (particularly shajuku). In view of the case in which soaking of the fillets in still water for a short time of 10 minutes or less can prevent for 12 months or more the generation of an unpleasant odor from sake-kezuribushi, it is preferable that the temperature of the water used for the soaking-in-water be 5 deg C or higher.

The soaking-in-water time of the fillets is generally 5 minutes-30 minutes, although the time depends on the temperature, volume, and other conditions (e.g., still water or flowing water) of the water used for soaking the fillets. It is preferable that the soaking time be 7 minutes or more in order to prevent the generation of an unpleasant odor from the sake-arabushi or sake-kezuribushi obtained in the subsequent manufacture processes, and that the soaking time be not more than 20 minutes in order to prevent deterioration of the freshness of the fillets, of the umami composition, or the flavor of sake-arabushi or sake-kezuribushi, and it is more preferable that the soaking time be 10 minutes-15 minutes.

The salt concentration of the water used for soaking-in-water is 5% or less by weight, as stated above, and this range of salt concentration hardly affects the prevention of the generation of an unpleasant odor. The generation of the unpleasant odor mentioned above is specific to sake-bushi, and such an unpleasant odor is not generated to a degree that a human being can detect by katsuo-bushi, saba-bushi, maguro-bushi, iwashi-bushi, or aji-bushi that is manufactured from other fish species. Therefore, in this embodiment, soaking-in-water is not implemented in manufacturing katsuo-bushi or katsuo-arabushi, because this process tends to cause the flavor of the finished katsuo-bushi or katsuo-arabushi products to deteriorate, or to cause the slices of finished products to change to a whitish color. Accordingly, in regard to securing the quality of finished products, the present invention's soaking-in-water, in connection with other process conditions described later, is important and unique in the manufacturing method of sake-arabushi or sake-kezuribushi.

The fillets can be soaked in water in various ways, including in still water, in flowing water (continuously flowing water), and so on.

Soaking in still water is a way of soaking the fillets in a container filled with still water of a predetermined temperature and for a predetermined amount of time. The greater the volume of water in the container, the more advantageous the conditions for manufacturing are, but from a practical standpoint and in view of preventing the generation of an unpleasant odor, it is preferable that the volume of water is 1.1 liters or more per unit weight (1 kilogram) of fillet and is 10 liters or less in view of economizing the use of water and the efficiency of the operation.
The preferable range of the water temperature in still-water soaking is 5 deg C-8 deg C, and the fillets' soaking time is from 10 minutes to less than 15 minutes. During that time, the water in the container may be stirred intermittently, e.g., 3 times at intervals of 1 minute-5 minutes, and a part of or all the water may be changed to new (unused) water (a water change;), so that the efficiency of preventing the generation of an unpleasant odor can be increased, the flavor of the finished products of sake-arabushi or sake-kezuribushi can be improved, and differences of quality among finished products can be reduced. The intermittently stirring of the water or changing the water must be done carefully, so as to prevent the fillets from crumbling.

Soaking in flowing water is a way in which fillets that have skin are put into a container filled with water for soaking, and the water is allowed to run on the surfaces of the fillets at a speed (linear velocity) within a predetermined range. This corresponds to intermittently but continuously stirring and changing the water as in the above-described soaking-in-still-water.
Soaking in flowing water is preferable to soaking in still water, inasmuch as soaking in flowing water results is less crumbling of fillets, the differences in quality among finished products can be made smaller in relation to flavor quality, and the generation of an unpleasant odor of sake-arabushi or sake-kezuribushi can be better prevented, because this soaking method allows the fillets to be efficiently treated in water in just a short time.

The volume of water in the container for soaking is sufficient if the fillets in the container are completely covered, because the water in the container flows. However, in order that the entire surface of all the fillets is covered by the flowing water, it is preferable that the volume of water is 1.1 liters or more per unit weight (1 kilogram) and is 10 liters or less in order to economize on the use of water and to maximize the efficiency of operation so as to be similar to soaking in still water.
In order to allow the water to flow, an inlet opening is provided at one sidewall of the container, and an outlet opening is provided at the other sidewall, although the process is not limited to this structure. At this time, it is preferable that the inlet opening be provided on one sidewall midway between the bottom of the sidewall and the surface of water or between the midway position and the bottom, and it is more preferable that the position of the inlet opening be near the internal surface of the bottom. It is preferable that an outlet opening be provided at the place on the other sidewall where an extension line in the direction of the water supply reaches, but the water can be allowed to overflow the other sidewall without an outlet opening being provided. The direction of the water supply in the direction of the depth of the container for soaking can be horizontal from the inlet to the outlet, and if an inlet opening is provided near the bottom, the direction of the water supply can be upward within the range where the extension line does not reach the surface of water. Also, in the middle of a predetermined soaking time, the direction of the water supply can be reversed so that water is delivered from the "outlet opening" and is discharged from the "inlet opening."

Although the volume of water flowing in the container depends of the size and shape of the container and the direction of the flow of water due to the position of the water supply inlet, it is preferable that the speed (linear velocity) at the surface of the fillets be 2 cm-10 cm per minute, and it is more preferable that the speed (linear velocity) at the surface of the fillets is 3 cm-9 cm per minute, and it is even more preferable that the speed (linear velocity) at the surface of the fillets be 5 cm-8 cm per minute. If the linear velocity is less than 2 cm per minute, the effect of the flow of water might not be sufficient, and if the linear velocity is more than 10 cm per minute the bodies of the fillets are likely to crumble, resulting in the lowering of their commercial value and the yield of the finished products.

(3) Skinning process
The skinning process is a process by which the skin of the fillet is removed. This process is not indispensable in the present invention's method for manufacturing sake-arabushi, but if the skin is not removed, it might be necessary, after the soaking-in-water step of subsequent manufacturing processes, for the frequency of smoking and drying to be increased in order to obtain satisfactory flavor quality; in addition, if sake-arabushi with skin is made into sake-kezuribushi, the skin gets mixed with the sake-kezuribushi, which causes the finished products to look unappealing, which might lower their commercial value.

Skinning can be performed prior to or subsequent to the shajuku process explained below, or subsequent to the first heating step, or subsequent to the second heating step in the smoking-and-drying process. Although in the manufacture of katsuo-bushi skinning is performed subsequent to shajuku, and simultaneously with boning, it is preferable, when manufacturing sake-arabushi, for skinning to be done prior to shajuku, so that the loss of yield (meat) is kept low (an average of 2%) and so that the skinning can be done in a short time (if a skinner can be used, the time to process one fillet is less than 5 seconds), so that cracks or void (empty) places tend not to result in the sake-arabushi obtained in the subsequent manufacturing processes. If skinning is done after shajuku (after cooling at a normal temperature), the meat of the fillet might crumble, cracks or empty places might occur in the sake-arabushi, and the loss of yield (meat) can reach as high as an average of 10%, and also the work for skinning might require more time (2 minutes-10 minutes per fillet). If skinning is done subsequent to the first heating step in the smoking-and-drying process, the loss of yield (meat) is a little bit less (an average of 8%) than if done subsequent to the shajuku process, but the crumbling of the meat or difficulties in the skinning is similar to when the work is done subsequent to the shajuku process. If skinning is performed subsequent to the second heating step, cracks or void (empty) places tend not to occur in the sake-arabushi obtained by the subsequent manufacturing processes, and the loss of yield (meat) is lower (an average of 5%) than if skinning is done subsequent to the first heating step, but the skinning is not done efficiently compared to that done subsequent to the first heating step, and such skinning takes more time (5 minutes-10 minutes per fillet).

Skinning can be done by hand using only a fish knife. To be more precise, a fillet is fixed by its tail to a working plate, the blade of a fish knife is inserted between the meat and the skin of the fillet at the tail, and the skin is removed from the tail to the head. Also, a commercially available skinner, e.g., a skinner having a tooth-shaped rotary roller on its outer circumference (Maja's model ESM 435 or EVM 437 marketed by TOA Koeki Co., Ltd.) can be used. It is preferable that the entire skin be removed, but one-half or one-third of the skin might be removed instead.

(4) Shajuku process
The shajuku process is a process in which the fillets are soaked in hot water, and by which the protein in the raw meat is denatured. Shajuku can be applied to both fillets that have skin and that have received soaking-in-water, and to fillets whose skin has been removed subsequent to soaking-in-water.
Steaming can also denature the protein, but this might generate an unpleasant odor in the sake-kezuribushi that is obtained, though performing shajuku subsequent to soaking-in-water can prevent the unpleasant odor. Accordingly, in the present invention's method for manufacturing sake-arabushi, shajuku is indispensable, along with soaking-in-water.

Although shajuku can be implemented in various forms, a representative form that can be implemented on an industrial scale will be described below. Fillets are laid in baskets, which are put into heated water in a shajuku tank so that the fillets are soaked in hot water. If fillets having skin are used, it is preferable that the fillets be laid with the skin surface on the basket so as to allow the skin to be easily removed after the fillets are soaked.
The shajuku tank can be heated directly, but it is preferable that electric heating or heating using a boiler, which makes it easy to control the temperature of the water in the tank (e.g., within plus minus 2 deg C) is performed. The temperature profile of the fillets during shajuku is acknowledged to have a subtle influence on the properties of finished sake-kezuribushi, and therefore shajuku is an important control factor.

It is preferable that the temperature of the water into which either of the above-described two types of fillets are put is 60 deg C or higher (when the temperature of water in the tank is controlled within plus minus 2 deg C, and the setting temperature's lower limit should be 62 deg C or higher) but less than 80 deg C (the setting temperature's upper limit should be less than 78 deg C), and it is more preferable that the temperature be 65 deg C or higher but not higher than 73 deg C (the setting temperature should be 67 deg C-71 deg C). If the temperature of water is less than 60 deg C, too much time is needed for the inside of the fillets to reach the preferred temperature, and in which time the meat of the fillet is stretched undesirably or the finished sake-kezuribushi might generate an unpleasant odor. If the temperature is 80 deg C or higher, cracks in the fillets might occur, and if the temperature is 90 deg C (or higher), cracks or twists in the fillets might occur or the meat of the fillets might burst open while that temperature is maintained or increased after the fillets have been put into hot water.

The hot water into which the fillets are put should not be heated immediately after the fillets are put into the water, but should be heated at least to the extent that the temperature of the hot water into which the fillets are put does not exceed the above-mentioned preferable temperature range of 60 deg C or higher but less than 80 deg C (in other words, at least to the extent that the temperature of the hot water into which the fillets are put does not exceed 80 deg C), or after the heating is stopped, the water temperature is to be maintained at 60 deg C or higher but to less than 80 deg C (non-elevated temperature). The time during which the non-elevated temperature is maintained is preferably 5 minutes-20 minutes, more preferably 7 minutes-13 minutes, and most preferably 10 plus minus 1 minutes. If the time for maintaining the non-elevated temperature is less than 5 minutes, a fishy odor might remain in the sake-kezuribushi obtained in the subsequent manufacturing processes, and if the time exceeds 20 minutes, shajuku will take too much time and the meat of the fillets might be stretched undesirably or the unsalted soluble-solids content (extract) might deteriorate.

After the water is maintained at such a non-elevated temperature, heating begins, and the maximum temperature to be reached inside the fillets is set to be preferably 84 deg C or higher but less than 90 deg C, and more preferably 86 deg C or higher but not more than 88 deg C. Shajuku is finished when the fillets are taken out from the hot water. If the maximum temperature to be reached inside the fillet is set to be less than 84 deg C, a fishy odor might remain in the sake-kezuribushi obtained in the subsequent manufacturing processes, and if the temperature is 90 deg C or more, cracks might occur in the meat of the fillets. The time from when heating the fillets begins to when the set maximum temperature is reached is preferably 30 minutes-60 minutes. In the rapid heating by which the above-specified preferable maximum temperature is reached within 30 minutes after heating begins, a fishy odor might remain in the sake-kezuribushi, and in the slow heating by which the above-specified preferable maximum temperature is reached within 60 minutes or more, the meat of the fillet might be stretched undesirably or the unsalted soluble-solids content (extract) might have deteriorated. The fillets can be removed from the hot water if the time for heating is 30 minutes-60 minutes from when the heating begins, even if the when the fillets are taken out is not immediately after the fillets have reached the set maximum temperature. The temperature of water in the tank is not limited, but it should be controlled so as to reach the above-specified preferable set maximum temperature of the fillets in 30 minutes-60 minutes after heating begins. However, the upper limit of the temperature of the heated water is preferably less than 90 deg C, even when the fillets are removed from the hot water immediately after the fillets reach the set maximum temperature due to the above-specified rapid heating.

In manufacturing katsuo-bushi, shajuku is performed, and it is known that shajuku has a large effect on the properties of the finished katsuo-bushi. In bonito, the fillet is thick, and its meat becomes firm as shajuku progresses, but in the salmon of the present invention, whose quality of meat differs from that of bonito, the fillet is thin and the meat is tender, even after shajuku. Accordingly, if the known manufacturing process of katsuo-bushi is directly applied to the present invention's process for manufacturing sake-arabushi, the shajuku will be excessive.

Subsequent to shajuku and prior to the subsequent smoking-and-drying, if the fillets are left in an ambience of 20 deg C or more for more than 1 day, they might become rotten due to Bacillus subtilis and other bacteria, and therefore steam sterilization is performed as one of the options to kill the bacteria. This steam sterilization is performed for about 10 minutes-30 minutes at a steam temperature of, e.g., 80 deg C-99 deg C. However, it is desirable that the maximum temperature to be reached inside the fillets is 88 deg C or less, as is similar to that during shajuku.

If the raw materials of salmon that have a raw-meat lipid content exceeding 4% by weight are used, it is possible to smoke and dry the fillets after reducing the lipids content by pressing the fillets when the protein of the fillets coagulates during shajuku. In press defatting, the fillets on which shajuku is performed are wound around by a mesh made of stainless steel or aluminum one by one, so as to prevent deformation in pressing. The fillets are pressed for 45 minutes-90 minutes, but only to the extent that the body of the fillet does not crumble. In this press defatting, a hydraulic press machine can be used in which the fillets that are wound around by metal mesh one by one are arranged on each shelf so as to be stacked in 10 layers-15 layers, and they are pressed all together for defatting. However, if this kind of press defatting is performed, cracks or crumbles in the fillets occur more or less, and therefore it is preferable to use raw materials of salmon that have a lipids content of 4% or less by weight, which does not require press defatting.

(5) Smoking-and-drying process
The smoking-and-drying process is a process by which the fillets on which shajuku has been performed are smoked and dried, and then are aged at a normal temperature (without heating) repeatedly, so that the fillets are transformed into sake-arabushi. Here, smoking-and-drying is a treatment by which the fillets are dried and smoked by a thermal air current, including smoke obtained by burning firewood or the like, and aging at a normal temperature is a treatment by which heating of the fillets is stopped, after which the fillets are kept intact so that the moisture inside them moves to their surface by preventing only the surfaces from being dried, so as to allow the inside of the fillets to dry out uniformly. Smoking-and-drying and aging at a normal temperature are combined so as to constitute one cycle, and this cycle is repeated. Smoking-and-drying step in the first cycle is called "the first heating step (ichibanbi)," smoking-and-drying step in the second cycle is called "the second heating step (nibanbi)," smoking-and-drying step in the third cycle is called "the third heating step (sanbanbi)," and so forth.

Smoking-and-drying can be performed by using such equipment as a kyuzokko, a yaizu-shiki dryer, a tebiyama, or other of various types of smoke generators, and can be performed by using a combination of such types of equipment. Here, the kyuzokko is a piece of equipment that (1) is composed of an (a) underground part in which smoke wood is burned, and (b) an aboveground part that is segmented into several layers, each of which is called a "muro," each of which is filled with hot air and smoke, (2) uses direct heating, and (3) smokes and dries the fillets through natural convection. The yaizu-shiki dryer is a piece of equipment that uses indirect heating, in which baskets that are piled on carts are placed in a drying room into which smoke is supplied by a fan. A tebiyama is a piece of equipment that includes a furnace that is made by forming walls using incombustible material or by digging a hole, and that uses direct heating; baskets having a size that covers the furnace are piled up thereon, and smoke wood is burned in the furnace, whereby the fillets are smoked and dried.
In this embodiment's smoking-and-drying process, the smoking-and-drying conditions to be applied to the fillets of salmon differ from those for bonito, because the fillet of salmon differs from that of bonito, in that a fillet of salmon is generally thinner than that of bonito, the quality of their respective meats are dissimilar, the moisture in the fillet of salmon is more easily dried than that of bonito, and the fillet of salmon to which shajuku is performed tend to get burned if they are heated at an ambient temperature of 85 deg C or higher. Oak or Japanese oak can be used as the smoke wood, but Japanese cherry wood is preferable because its sweet-odored smoke fits well with sake-arabushi or sake-kezuribushi. It is preferable that smoking-and-drying is performed intermittently at least to the sixth heating step, referred to as "rokubanbi."

In the smoking-and-drying conditions, the time required for smoking-and-drying differs according to the type of smoking-and-drying equipment that is used, but the smoking-and-drying temperature or the conditions of aging at a normal temperature are the same regardless of the equipment used. That is to say, under the typical conditions of manufacturing sake-arabushi according to the present invention at ambient temperatures, the smoking-and-drying temperature is 80 deg C-85 deg C during the first and second heating steps, 65 deg C-70 deg C during the third heating step, 60 deg C-65 deg C during the fourth heating step, and 56 deg C-65 deg C during the fifth and subsequent heating steps. The time required for smoking-and-drying greatly differs according to the smoking-and-drying equipment used. A tebiyama requires 1 hour-3 hours at each heating step, a kyuzokko requires 4 hours-9 hours at each heating step, a yaizu-shiki or a and smoke-generator dryer requires 4 hours-9 hours at each heating step.

In the typical conditions of manufacturing sake-arabushi according to the present invention, the aging-at a normal temperature (called anjou) consists of cooling at a normal temperature (0 deg C-30 deg C), with the fillets to which each step of smoking-and-drying is performed being cooled at such a temperature through natural thermal radiation, without using a cooling device, and being keeping intact at the normal temperature without any treatment after the cooling at a normal temperature. The time required for aging at a normal temperature in the respective heating steps is as follows: the time required for keeping the fillets intact subsequent to cooling at a normal temperature after the first heating step is 0 hours-36 hours, and preferably 0 hours-24 hours; the time required for keeping the fillets intact subsequent to the cooling at a normal temperature after the second heating step is 0 hours-36 hours, and preferably 0 hours-24 hours; the time required for keeping the fillets intact after the third heating step is 1 day-4 days, and preferably 2 days-3 days, including the time for both the cooling at a normal temperature and keeping the fillets intact; the time required for keeping the fillets intact after the fourth heating step is 2 days-6 days, and preferably 3 days-5 days, including the time for both the cooling at a normal temperature and keeping the fillets intact; and the time required for keeping the fillets intact after the fifth and subsequent heating steps is 4 days-21 days, and preferably 5 days-10 days, including the time for both the cooling at a normal temperature and keeping the fillets intact. As explained above, one or more of the steps of keeping the fillets intact subsequent to the cooling at a normal temperature in the aging at a normal temperature after the first and second heating steps are occasionally omitted (0 hours), and the smoking-and-drying is performed immediately after the cooling at a normal temperature.
In the first to fourth heating steps, because the moisture content of the fillet is rather high and the moisture tends to move to the surface of the fillet, the time required for the aging at a normal temperature in those steps is shorter than that in the fifth and subsequent steps. If the time for keeping the fillets intact is made longer in the first to fourth heating steps, deterioration in the quality of the fillet due to proliferation of microorganisms in the moisture that has moved to the surface might occur if the outside air temperature becomes 10 deg C-20 deg C or higher. If there is concern about such deterioration in quality due to the proliferation of microorganisms, the fillets can be kept in a refrigerator at a temperature of 10 deg C or less, and in such a case, the time for keeping the fillets intact can be lengthened. Also, because the moisture content in the fillets is sufficiently low during the fifth and subsequent steps, even if the fillets are kept at a normal temperature, the time for keeping the fillets intact can be increased up to 21 days in total.

After smoking-and-drying is finished, the fillet is transformed into sake-arabushi, whose moisture content is 12%-21% by weight. The lipids content of sake-arabushi would be 7%-8% by weight if raw salmon having a lipids content of 3.5% by weight is used as the raw materials, and 11%-12% by weight if raw salmon having a lipids content of 5.5% by weight is used as the raw materials and if press defatting is not performed on the salmon during manufacturing.

(6) Manufacturing of sake-kezuribushi
Sake-kezuribushi is manufactured by slicing sake-arabushi. In the present invention, it is preferable that first sake-kezuribushi manufactured in the smoking-and-drying process be kept intact and aged at the normal temperature, including sun drying for 2 days-3 days or more, and then be introduced into the sake-kezuribushi manufacturing process. Before sake-kezuribushi is put on the market, generally the following manufacturing steps take place: (1) washing and heating for sterilization; (2) cutting of sterilized sake-arabushi slices; and (3) placing those slices into a pouch made of material that does not allow gases from outside to permeate into the pouch, and (4) replacing the gas in the pouch by an inert gas.

Typical operations performed during the manufacture of sake-kezuribushi are explained below. Sake-arabushi is washed in clean water (tap water) by using a brush, and sterilization by heating is performed by dry sterilization (e.g., for 30 minutes-120 minutes at 160 deg C-200 deg C) or by steam sterilization (e.g., for 10 minutes-45 minutes at a steam temperature of 80 deg C-99 deg C). If the sterilization by heating is performed by steam sterilization, it is preferable that sterilized sake-arabushi is kept intact for 1 hour-24 hours at a temperature between the temperature at which water does not freeze and 10 deg C or less, so as to allow the sake-arabushi to dry out uniformly. The obtained sake-arabushi is sliced without molding. Sake-arabushi can be sliced by using a slicer that is similar to that used in slicing katsuo-bushi, so as to produce slices of optional thickness, such as thin ones of 0.01 mm-0.2 mm, or thick ones of 0.21 mm-1.0 mm.

In the sake-kezuribushi of this embodiment, if sake-arabushi having a lipids content of 7.7% by weight and having lipids content of 11.7% by weight are cut into slices, 8.5% by weight and 15.3% by weight, respectively of the sake-arabushi become powder. Both the thin and thick slices do not present any unpleasant eye-irritating odor.

Such slices of sake-kezuribushi are packed in a pouch made of material that does not allow gases from outside to permeate into the pouch, and the gas inside the pouch is replaced by an inert gas such as nitrogen, helium, or argon, so that finished products of sake-kezuribushi (packed in a pouch) are manufactured. The preferable inert gas is nitrogen. Also, each pouch can be sealed off after slices are packed in it and an oxygen absorber is inserted into it, whether or not the gas inside the pouch is replaced by an inert gas. In addition, although the thinner slices tend to collapse when they are packed, vacuum packing can be used to produce the finished products. A pouch made of multi-layered laminate film used for packaging gyobushi, including katsuo-bushi, can be preferably used as a pouch made of material that does not allow gases from outside to permeate into the pouch, though the pouch is not limited thereto. For example, multilayer film that is laminated over monolayer film (the thickness of each: 10 um-50 um) such as polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH), low-density or high-density polypropylene (LLDPE or HDPE), or polyethylene terephthalate (PET) are preferably used. Finished products packaged like this are sufficiently palatable without generating an unpleasant odor as mentioned above, even six months after production. It has also been demonstrated that the finished products do not generate an unpleasant odor even 12 months after production.

Example

1. Methods used in pretreatment
A: In this embodiment, fillets having skin were produced using as raw materials female chum salmon in the period of before-or-after egg collection or spawning in the salmon's natal stream. The salmon used as raw materials in this example were dressed and frozen, and were defrosted (thawed) by water on the day previous to when the fillets were produced. The next morning, the salmon as raw materials were washed in a defrosting tank so as to remove dirt from their surfaces, and after their heads, fins and shoulder girdles were removed, the salmon were cut away from salmon's spine. The weight per fillet having skin obtained by the above treatment ranged from 490 g-607 g. In such fillet having skin, the moisture content was 73%-77% by weight, and the lipids content was 2.0%-3.0% by weight. (In the raw materials, similar amounts of moisture and lipids, respectively were obtained.) The moisture content was measured by a dry technique by heating under normal pressure according to Shokuhin Eisei Kensa Shishin, Rikagakuhen, (Guide for Food Sanitation Examination, Physicochemistry), published by the Japan Food Hygiene Association (2005, Tokyo), and the lipids content was measured using Soxhlet's extractor and an extracting method according to the above-mentioned Shokuhin Eisei Kensa Shishin, Rikagakuhen. (The methods of measuring moisture content and lipids content are the same for all the examples mentioned below unless specifically indicated otherwise.)

B: Fillets having skin were produced in a way similar to that described in the above section A, using male chum salmon which had not gone upstream and in which the nuptial color had appeared. (Some of them had shown a change of shape, including the curvature of the snout.) The weight per fillet having skin obtained ranged from 513 g-650 g. In that fillet having skin, the moisture content was 70%-74% by weight, and the lipids content was 3.1%-4.7% by weight.

2. Study of the conditions of soaking-in-water
Experimentation was conducted in order to identify the optimum conditions for obtaining fillets of better quality in the soaking-in-water treatment, including the soaking-in-still-water method and the soaking-in-flowing-water (soaking-in-continuously-flowing-water) method, using 10 pieces-70 pieces of fillets having skin (in each experimental condition) produced from the female chum salmon in the pretreatment process described in the above section A.

2.1 Experimentation regarding soaking-in-still-water
Experimentation was conducted to study the conditions for soaking fillets having skin, using a container for soaking (square-shaped, with a flat bottom, having a volume of 30 liters-50 liters), and using as clean water either tap water, seawater (salt concentration of 3.3 w/v%), deep sea water off the coast of Raus of Hokkaido (salt concentration of 3.3 w/v%), or a saline solution (salt concentration of 3 w/v%, 5 w/v%, and 7 w/v%). Parameters used in the experimentation were: volume of water for soaking, frequency of (intermittent) stirring, frequency of water change, soaking temperature, and soaking time. The change in the properties (external appearance, color, and odor) of the fillets having skin was observed, so as to identify whether a fishy odor remains, whether the deterioration of freshness of the fillet, such as indicated by undesirable stretching of the meat or softening of the quality of meat exists, or the degree of deterioration of freshness. Except for the fillets having skin to be examined exposed to certain conditions, in which deterioration of freshness had been confirmed, the fillets having skin to be examined, to which the soaking-in-water treatment was performed, were subjected to a series of treatments according to the conditions of the respective processes for manufacturing sake-arabushi and sake-kezuribushi, as explained below. Using as fillets to be examined those fillets having skin, packaged samples of sake-arabushi and sake-kezuribushi were produced and then observed in regard to their flavor, including generation of an unpleasant odor specific to sake-bushi over time.

After the above-specified examination, the fillets with skin were subjected to the various conditions relating to the soaking-in-water treatment and then drained, and all the skin of the fillets to be examined was removed using skinners (Maja's model ESM 435 and EVM 437, marketed by TOA Koeki Co., Ltd.) (the skinning process). The fillets from which the skin had been removed were placed into hot water having a temperature of 70 deg C plus minus 2 deg C (in a shajuku tank), and were maintained at non-elevated temperatures for 7 minutes-10 minutes. Then, heating began, and the fillets were heated to 86 deg C-88 deg C within 40 minutes-50 minutes, and then they were removed from the hot water (shajuku). The fillets to which shajuku had been applied were smoked and dried intermittently in a yaizu-shiki dryer, using chips of Japanese cherry wood as the smoke wood, up through the aforementioned sixth step so as to obtain sake-arabushi. The temperature of the heat applied to the fillets during the smoking-and-drying process was as follows: ambient temperature of 80 deg C-85 deg C during the first and second heating steps; ambient temperature of 65 deg C-70 deg C during the third heating step; ambient temperatures of 60 deg C-65 deg C during the fourth heating step; and ambient temperature of 56 deg C-65 deg C during the fifth and sixth heating steps. The time for smoking-and-drying was the same in the first heating step through the sixth heating step, 6 hours-7 hours, and aging at a normal temperature was performed in such a way that the fillets were cooled at a normal temperature (uncontrolled temperature of 15 deg C-30 deg C) subsequent to the respective heating steps, after which the fillets were kept intact for a predetermined time. The time required for aging at a normal temperature was as follows: the time in which the fillets were kept intact subsequent to the cooling at a normal temperature was 12 hours after the first heating step; the time in which the fillets were kept intact subsequent to the cooling at a normal temperature was 22 hours after the second heating step; the combined time required for cooling at a normal temperature and the time in which the fillets were kept intact was 3 days after the third heating step; the combined time required for cooling at a normal temperature and the time in which the fillets were kept intact was 5 days after the fourth heating step; and the combined time required for cooling at a normal temperature and the time in which the fillets were kept intact was 7 days after the fifth and the sixth heating steps.

The obtained sake-arabushi were washed with tap water and sterilized by heating using steam sterilization (for 20 minutes at a steam temperature of 95 deg C plus minus 3 deg C) and kept intact at a low temperature (for 3 hours at 5 deg C plus minus 3 deg C), after which they were cut into slices having a thickness of 0.1 mm-0.2 mm, so as to make sake-kezuribushi. The obtained sake-kezuribushi was placed into a pouch (size: 115 mm x 135 mm) made of material that does not allow gases from outside to permeate into the pouch, with 5 g of sake-kezuribushi put into each pouch, and the gas in the pouch was replaced by nitrogen, so that packaged samples of sake-kezuribushi under the various soaking-in-water conditions were prepared. The pouch material that does not allow gases from outside to permeate into the pouch was a laminated film --- made of biaxially-oriented polypropylene (PP) film (thickness: 20 um), a dry laminate, ethylene-vinyl alcohol (EVOH) (thickness: 12 um), an anchor coat, polyethylene (PE) (thickness: 15 um), and a linear low-density polyethylene (LLDPE) (thickness: 40 um) --- manufactured by Dai Nippon Printing Co., Ltd. There was also prepared a control that was not subject to soaking-in-water but whose other production conditions were the same as those specified above.

The various packaged samples and the control were preserved indoors (at a temperature of 11.0 deg C-36.0 deg C, humidity of 44%-89%). A sensory evaluation of the flavor was performed every 2 weeks for up to 2 months after the samples were first preserved, and thence every month after those 2 months, focusing on the whether any unpleasant odor was generated.

The experimentation using seawater (including deep-ocean water) or saline solution for the soaking-in-water was performed under the conditions in which deterioration of the freshness of the fillets having skin was not observed and the generation of an unpleasant odor of packaged samples was prevented during the experimentation using clean water in the soaking-in-water treatment. In this experimentation, the following points were checked: the deterioration of freshness; sensory evaluation of flavor including generation of an unpleasant odor: and salt content (% by weight) in sake-kezuribushi.

The salt concentration in seawater and the salt content in sake-kezuribushi were measured using a salt analyzer (SAT-500, manufactured by DKK-TOA Corporation). In order to measure the salt content in sake-kezuribushi, a sample solution was prepared according to the Japanese Agricultural Standards method (JAS: Last amended by Notification of the Ministry of Agriculture, Forestry, and Fisheries No. 1272 on August 6, 2008) for measuring the unsalted soluble-solid content (extract) of kezuribushi, as follows: a crushed sample was obtained by putting the crushed kezuribushi through a sieve having an opening of 850 um, as provided for by JIS Z 8801-1; the 5-g sample obtained after straining through the sieve of 5 g was placed into a 500-ml Erlenmeyer flask having a reflux condenser (cooling pipe); deionized water of 245 g was added to the sample and boiled for 20 minutes in the flask, with occasional shaking: and the content of the flask was passed through a filter so as to obtain a sample solution after the flask had cooled.

The results of experimentation of soaking-in-water using the still-water soaking method are shown in Table 1 through Table 13. The signs in the tables show the following: the "-" sign indicates that no deterioration of freshness or an unpleasant odor was detected; the sign "+- (plus minus)" indicates that a slight deterioration of freshness or a slight unpleasant odor was detected; the sign "+" indicates that a clear deterioration of freshness or a clearly unpleasant odor was detected; and the sign "++" indicates that a distinct deterioration of freshness or a distinct unpleasant odor was detected.

Table 1 shows that the control, to which soaking-in-water was not performed, presented a slightly unpleasant odor after 2 weeks had elapsed since the kezuribushi had been packaged; the unpleasant odor had gradually increased after 1 month had elapsed; and the unpleasant odor was strong after 3 months had elapsed.
If fillets having skin were soaked in still tap water of 1.1 liters or more per 1 kilogram of the fillets for 5 minutes or more, although some of packaged samples soaked in water having a temperature of 0 deg C (0 deg C plus minus 1 deg C) presented a slight unpleasant odor after 6 months had elapsed, it was confirmed that soaking-in-still-water could prevent the generation of an unpleasant odor. The results shown in Table 1 through Table 13 indicate that if the water temperature exceeded 20 deg C, the freshness of the fillets deteriorated. Although the soaking time or the volume of water used for influenced the freshness of the fillets, it was confirmed that to prevent the deterioration of the freshness of the fillets, the temperature of water used for soaking should be as low as possible unless the water is frozen, and it was also found that soaking fillets having skin in clean water having a temperature of 20 deg C or less for 5 minutes-30 minutes could prevent the generation of an unpleasant odor for at least 6 months.

If the salt concentration of water in which the fillets were soaked exceeded 5% by weight, no unpleasant odor was detected, as was similar with the use of water whose salt concentration was 5% by weight or less, but the sake-kezuribushi obtained showed high salt content, and tasted salty to the extent that the sake-kezuribushi could not be eaten on a daily basis. It was found that if a saline solution or seawater whose salt concentration was 5% or less by weight was used, the unpleasant odor could be prevented, as was similar to when clean water was used, and the obtained sake-arabushi and sake-kezuribushi were satisfactory, having good flavor quality. In addition, it was found that soaking the fillets in water having a temperature at 5 deg C-8 deg C for 7 minutes-14 minutes prevented the generation of an unpleasant odor for up to 12 months, and sake-arabushi and sake-kezuribushi having good flavor quality were obtained, even if the soaking time was not long. Also, in still-water soaking, if the volume of water in which the fillets were soaked was less than 1.1 liters per 1 kilogram of fillet having skin, an unpleasant odor was not always uniformly prevented, irrespective of the temperature of the soaking water and the soaking time. In this case, the following measures were effective in shortening the soaking time and preventing the unpleasant odor: to set the volume of water in which the fillets were soaked at 1.1 liters or more per 1 kilogram of fillet having skin; to stir the water one or more times intermittently; and to change the water in which the fillets were soaked one or more times. Moreover, reuse of the soaking water (tap water) of 1.1 liters per 1 kilogram of the fillets at 5 deg C was tested, with the fillets being soaked for 5 minutes (not shown in Table 2), but the water that was intended for reuse contained a large amount of impurities, and therefore it was not practical to use such water.

2.2 Experimentation regarding the flowing-water method
The effects of soaking-in-water were examined as follows: a container for soaking (square-shaped with a flat bottom, having a volume of 40 liters; a cross-section of the flowing water [which is the same as the lateral area of the water-supply-side wall or the lateral area of the outlet-side wall]: 1800 cm²) was filled with water at a predetermined temperature, in which the fillets were soaked; and the flow of water was such that the water came into the container from an inlet opening on one sidewall, flowed on the surfaces of the fillets, and flowed out from an outlet opening on the other sidewall.
In this experiment, the inlet opening on the water-supply-side wall was provided so that the bottom of the opening contacted the bottom surface of the container, and the outlet opening on the outlet-side wall was provided at the top of the wall. The water was supplied from a separately provided constant-temperature water tank (TRL-101FL model manufactured by THOMAS KAGAKU Co., LTD.) to the inlet opening of the container using two conveying pumps (TRL 140 and CP 808, both models manufactured by THOMAS KAGAKU Co., LTD.).

The experimentation regarding the flowing-water method was performed using clean water (tap water); the parameters of the experimentation were as follows: the volume of water per 1 kg of the fillets supplied to the container (L); the temperature of the water (at the beginning of the water flowing and that at the ending of the water flowing are the same); the time of the water flowing; and the liner velocity of the flowing water. After soaking-in-water was performed under various conditions, the following properties (external appearance, color, odor) of the fillets having skin were observed: the presence of crumbles of the fillets; degree of crumbling of the fillets; and the deterioration of the fillets' freshness, such as the presence of a fishy odor, undesirable stretching of the meat, or softening of the meat quality. Except for fillets having skin to be examined exposed to certain conditions, in which deterioration of freshness has been confirmed, the fillets having skin to be examined, to which the soaking-in-water treatment was performed, were subjected to a series of treatments according to the conditions of the respective processes, similar to those in the above "2.1 Experimentation regarding soaking-in-still-water" for manufacturing sake-arabushi and sake-kezuribushi. Using those fillets having skin to be examined, packaged samples of saketora-bushi and sake-kezuribushi were produced, and then those packaged samples were observed over time in regard to their flavor, including the generation of an unpleasant odor specific to sake-bushi.

Using seawater or saline solution under the conditions that the temperature of water was 7 deg C plus minus 1 deg C, the time of water flowing was 5 minutes and 10 minutes, respectively, and the liner velocity of the flowing water in the container was 5.6 cm per minute, the prevention of an unpleasant odor was achieved to an extent similar to that under the conditions using clean water, and therefore other detailed examinations under other conditions using seawater or saline solution were not performed.

The results of the experimentation regarding soaking-in-water using the flowing-water method are shown in Table 14 through Table 20. The signs of "-", "+- (plus minus)", "+", and "++" in the tables show the same contents as those in the above "2.1 Experimentation regarding soaking-in-still-water." Allowing the fillets having skin to contact clean water at a temperature between that at which water does not freeze (0 deg C plus minus 1 deg C) and less than 20 deg C (plus minus 1 deg C) for 5 minutes-30 minutes prevented the generation of an unpleasant odor for at least 6 months, so that sake-arabushi and sake-kezuribushi of good quality and good flavor could be manufactured under those conditions. Also, if the liner velocity of the flowing water was set at 3 cm per minute, even under the conditions that the temperature of water was 0 deg C plus minus 1 deg C and the soaking time was 5 minutes, generation of an unpleasant odor from the packaged samples of sake-kezuribushi could be prevented for 12 months or more. If the liner velocity of the flowing water was 11.1 cm per minute, crumbling of the fillets having skin was widely observed; and if the liner velocity of the flowing water was 8.3 cm per minute, partial crumbling of the fillets having skin was observed. Therefore, it was determined that the preferable condition for the flowing water (water supply) was a liner velocity of 10 cm per minute or less, and that a more preferable condition was a liner velocity of 8 cm per minute or less.

3. Shajuku
Experimentation regarding shajuku was conducted using fillets obtained by the following procedures: the fillets having skin (of female chum salmon) obtained in the above section "(1) Pretreatment" (paragraph [0014]) were used; soaking-in-water was performed using the flowing-water method under for the following: water temperature: 5 deg C (plus minus 1 deg C); soaking-water volume of 1.2 liters per 1 kg of fillet; water-flowing time: 5 minutes; and liner velocity of 5.6 cm per minute; the skin of the fillets was removed using skinners (Maja's model ESM 435 and EVM 437 marketed by TOA Koeki Co., Ltd.).

The fillets were laid on baskets, and were put into heated water in a shajuku tank (heated by a boiler, control accuracy of plus minus 2 deg C of the temperature of water in the tank) so that the fillets were soaked in hot water, and then the temperature of the hot water was increased. The parameters of the experimentation were as follows: temperature of the hot water when the fillets were put into the water; amount of time that the temperature of water was maintained at a level from which the temperature was not increased (non-elevated-temperature-maintaining time); amount of time from the beginning of the temperature increase to the ending of shajuku (speed of temperature increase, and pattern of temperature increase); maximum temperature of water when heated; and maximum temperature of fillets when shajuku was finished. The properties of the fillets (external appearance, color, odor) under the respective conditions during or after shajuku were observed in regard to the presence of a fishy odor, undesirable stretching of the meat, and cracking. Samples of sake-arabushi and sake-kezuribushi were prepared under the same conditions --- in terms of the treatment processes, including smoking-and-drying and other processes subsequent to smoking-and-drying --- as those in the above "2.1 Experimentation regarding soaking-in-still-water." The properties of the prepared samples were observed over time in regard to fishy odor, cracks, and void (empty) places, and flavor, including generation of an unpleasant odor specific to sake-bushi. The cracks and void (empty) places of the samples were identified by visual inspection. In order to identify the cracks and void (empty) places of the fillets and sake-arabushi, samples were cut at the longitudinal middle using a cutter in the thickness direction, and their cut surfaces were observed visually.

The results of this experimentation regarding shajuku are shown in Table 21. The signs of "-", "+- (plus minus)", "+", and "++" in the table refer to the same contents as those in the above "2.1 Experimentation regarding soaking-in-still-water." It was found that a fishy odor did not remain, cracks and void (empty) places did not occur, and the sake-arabushi and sake-kezuribushi had good flavor under the following shajuku conditions: the temperature of water when the fillets were put into the water was between 60 deg C (the temperature of water in the tank was controlled within plus minus 2 deg C, and the setting temperature's lower limit was 62 deg C or higher) and 80 deg C (the setting temperature's upper limit was not higher than 78 deg C); the water was maintained at a non-elevated temperature for 5 minutes-20 minutes; after that, heat was applied to the water so as to increase the water's temperature; within 30 minutes-60 minutes after the heating started, the fillets' temperature to be reached was set to be 84 deg C or higher but below 90 deg C.

Experimental Example 1 (A: female chum salmon after return to natal stream; flowing tap water; shajuku conditions for obtaining good-quality finished products)
Soaking-in-water was performed according to the above "2.2 Experimentation regarding the flowing-water method" (paragraphs 0073-0076) as follows: fillets (of female chum salmon) having skin prepared according to the above "1. Methods used in pretreatment" (paragraphs 0048-0049) were used; a container for soaking (square-shaped with a flat bottom; volume: 40 liters; cross-section of flowing water: 1800 cm²) was filled with tap water at 5 deg C (plus minus 1 deg C) at a quantity of soaking water of 1.2 liters per 1 kilogram of fillets having skin; the fillets were put into said container; tap water at 5 deg C (plus minus 1 deg C) was run in the container for 5 minutes at a linear velocity of 5.6 cm per minute. Subsequent to the soaking-in-water, skinning was performed, and the skin of the fillets was removed by using skinners (Maja's models ESM 435 and EVM 437, marketed by TOA Koeki Co., Ltd.). Subsequently, shajuku was performed according to the above "3. Shajuku" (paragraphs 0084-0086) as follows: the fillets that were skinned were put into water heated to 73 deg C (using a shajuku tank heated by using a boiler; control accuracy of plus minus 2 deg C of temperature of water in the tank); after the fillets were put into the water and the boiler was stopped, the water was maintained at a non-elevated temperature for 10 minutes; then heat began to be applied to the water at 69 deg C; 37 minutes after beginning the heating to the water-temperature upper limit of 89 deg C, the fillets were taken out from water, at the fillet maximum temperature to be reached of 87 deg C. The fillets to which shajuku was performed were smoked and dried in a kyuzokko up through the sixth heating step, using chips of Japanese cherry wood as the smoke wood, so that sake-arabushi was obtained. The smoking-and-drying temperatures were as follows: the ambient temperature during the first and second heating steps was 80 deg C-85 deg C; the ambient temperature during the third heating step was 65 deg C-70 deg C; the ambient temperature during the fourth heating step was 60 deg C-65 deg C; and the ambient temperature during the fifth and sixth heating steps was 56 deg C-65 deg C. The time for smoking-and-drying was 5 hours, which was the same for the first through sixth heating steps. Aging at a normal temperature was performed subsequent to the smoking-and-drying activities as follows: the fillets were left at a normal temperatures (uncontrolled temperatures of 15 deg C-30 deg C) for cooling, and then were kept intact for a predetermined time. The time required for aging at a normal temperature was as follows: the time required for keeping the fillets intact subsequent to cooling at a normal temperature after the first heating step was 12 hours; the time required for keeping the fillets intact subsequent to cooling at a normal temperature after the second heating step was 24 hours; the time required for keeping the intact after the third heating step was 3 days, including the time for both cooling at a normal temperature and keeping the fillets intact; the time required for the keeping the fillets intact after the fourth heating step was 5 days, including the time for both cooling at a normal temperature and keeping the fillets intact; and the time required for keeping the fillets intact after the fifth and subsequent heating steps was 7 days, including the time for both cooling at a normal temperature and keeping the fillets intact. The obtained sake-arabushi were washed by tap water and sterilized by heating using steam sterilization (for 20 minutes at a steam temperature of 95 deg C plus minus 3 deg C) and were kept intact for 3 hours at 5 deg C plus minus 3 deg C, and were then were cut, using a slicer, into slices having a thickness of 0.1 mm-0.2 mm, whereby packaged sake-kezuribushi was obtained.

Experimental Example 2
Treatment at each step was performed in a way similar to that of Experimental Example 1 according to the above "2.1 Experimentation regarding soaking-in-still-water," except for the following: seawater at 5 deg C plus minus 1 deg C was used; the volume of water in which the fillets were soaked was 1.4 liters per 1 kilogram of fillet having skin; and the total soaking time was 10 minutes (5-minute soaking with one water change).

Experimental Example 3
Treatment at each step was performed in a way similar to that of Experimental Example 1 according to the above "2.2 Experimentation regarding the flowing-water method," except for the following: seawater at 7 deg C plus minus 1 deg C was used; the liner velocity of the flowing water was 2.0 cm per minute; and the water-flowing time was 10 minutes.

Experimental Example 4
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: skinning was manually performed --- in accordance with the skinning process of the above "3. Shajuku" --- subsequent to shajuku (after cooling at a normal temperature) instead of skinning prior to shajuku.

Experimental Example 5
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: skinning was manually performed --- according to the skinning process of the above "3. Shajuku" --- subsequent to the first heating step of the smoking-and-drying process (after aging at a normal temperature), with skinning taking 2 minutes-7 minutes per fillet, instead of performing skinning prior to shajuku (2 minutes-7 minutes per fillet).

Experimental Example 6
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: skinning was manually performed --- according to the skinning process of the above "3. Shajuku" --- subsequent to the second heating step of the smoking-and-drying process (after aging at a normal temperature) with skinning taking 5 minutes-10 minutes per fillet, instead of performing skinning prior to shajuku.

Experimental Example 7
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: during shajuku, the temperature of water when the fillets were put into the water was 60 deg C (plus minus 2 deg C); the water was maintained at a non-elevated temperature for 20 minutes; and then heat was applied to the water so that the fillets' temperature would be 86 deg C when 65 minutes had elapsed since the start of heating.

Experimental Example 8
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: during shajuku, the temperature of water when the fillets were put into was 75 deg C (plus minus 2 deg C); the water was maintained at a non-elevated temperature for 20 minutes; and then heat was applied to the water, with the upper water temperature being 90 deg C, so that the temperature of the fillets would reach 90 deg C when 60 minutes had elapsed since the start of heating.

Experimental Example 9
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: instead of shajuku, fillets without skin that were obtained after the skinning process were steamed at an ambient temperature of 90 deg C-95 deg C.

Experimental Example 10
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: during smoking-and-drying, oak chips were used as the smoke wood.

Experimental Example 11
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: during smoking-and-drying, a yaizu-shiki dryer was used, and the time spent for smoking-and-drying was the same 6 hours for each of the steps of the smoking-and-drying process.

Experimental Example 12
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: during smoking-and-drying, a smoke generator was used, and the time spent for smoking-and-drying was the same 4 hours for each of the steps of the smoking-and-drying process.

Experimental Example 13
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: during smoking-and-drying, a tebiyama was used, and the time for smoking-and-drying was the same 2 hours for each of the steps of the smoking-and-drying process.

Experimental Example 14
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: in the smoking-and-drying process, the smoking-and-drying was performed through the fifth heating step.

Experimental Example 15
Treatment at each step was performed in a way similar to that of Experimental Example 1, except for the following: in smoking-and-drying, the smoking-and-drying temperature was 86 deg C-90 deg C during the first and second heating steps.

Experimental Example 16
Treatment in each process was performed in a way similar to that of Experimental Example 1, except for the following: smoking-and-drying was performed at each step to the eighth heating step, and the conditions of the seventh and eighth heating steps of smoking-and-drying were as follows: the fillets were smoked and dried for 4 hours at an ambient temperature of 56 deg C-65 deg C; and the time for aging at a normal temperature was 8 days and 10 days for the seventh and eighth steps, respectively.

Experimental Example 17
Treatment in each process was performed in a way similar to that of Experimental Example 1, except for the following: fillets (of male chum salmon) that have skin and that were prepared according to the above "1. Methods used in pretreatment" (paragraphs 0048-0049) were used.

Experimental Example 18
Treatment in each process was performed in a way similar to that of the above Experimental Example 17, except for the following: among fillets (of male chum salmon) that have skin and that were prepared according to the above "1. Methods used in the pretreatment" (paragraphs 0048-0049), the fillets used as raw materials were those having a lipids content exceeding 4% by weight (4.5%-4.7% by weight); manual defatting was performed of the fillets to which shajuku had been performed prior to smoking-and-drying. Defatting was performed as follows: the fillets were wound around one by one by a stainless mesh and were laid out in a row; the laid-out fillets were covered with a stainless steel plate that contacted the stainless mesh; it took 55 minutes-65 minutes to complete the defatting, during which a weight was placed on the stainless steel plate successively at intervals of 10 minutes-15 minutes so as to maintain a pressure range of 0.5 kg/cm²-5 kg/cm².

Comparative Example 1
Treatment in each process was performed in a way similar to that of Experimental Example 1, except that soaking-in-water was not performed.

Comparative Example 2
Treatment in each process was performed in a way similar to that of Experimental Example 1 except that soaking-in-water was not performed and for the following: in smoking-and-drying, each step was performed up to the eighth heating step, and the conditions in the seventh and eighth heating steps of smoking-and-drying were as follow: the fillets were smoked and dried for 4 hours at an ambient temperature of 56 deg C-65 deg C; and the time for aging at a normal temperature was 8 days and 10 days for the seventh and eighth steps, respectively.

Comparative Example 3
Sake-bushi (packaged sake-kezuribushi) marketed by other manufacturers were obtained and used from 1 week to 1 month before their "best-before" period expired.

Reference Examples
Katsuo-arabushi and kezuribushi (products marketed by NINBEN Co., Ltd.; 3 months after manufacture) were used.

A Study of the Examples
With regard to the samples of sake-arabushi, sake-kezuribushi, and packaged sake-kezuribushi produced according to the manufacturing conditions for the various experimental examples and comparative examples: (1) the following were observed: the external appearance included cracks and void (empty) places in the meat; undesirable stretching of the meat; crumbling of the meat; odors, including unpleasant odors; fishy odor; ammonia odor; other odors indicating spoilage; flavor, determined by sensory evaluation; and (2) the following were measured: yield of the fillets; percentage of powder as a constituent; moisture content; salt content; lipids content; unsalted soluble-solids content (extract); free amino acids; inosinic acid content; inosine content; and hypoxanthine content. In particular, the percentage of moisture, salts, and lipids as constituents of the fillets was measured subsequent to soaking-in-water and subsequent to shajuku, and subsequent to the respective steps of smoking-and-drying. The tests for the above, including moisture content, salt content, and lipids content, were conducted according to the method referred to above, and other items were tested in the manner explained below. The tests of kezuribushi regarding the percentage of powder as a constituent, moisture content, salt content, lipids content, unsalted soluble-solids content (extract), free amino acids, inosinic acid content, inosine content, and hypoxanthine content were conducted using samples of sake-kezuribushi before being packaged. The conditions for packaging and preserving of sake-kezuribushi were the same as those referred to in the above "2. The conditions of soaking-in-water" (paragraph 0050), and the properties (sensory evaluation for flavor, including unpleasant odor) were checked every two months after packaging. Also, it was not possible to identify the unpleasant odor's causative substances, although a gas-detecting tube (manufactured by GASTEC Corporation) and a gas chromatograph-MS (Mass Spectrometry) were used for that purpose.

Test Method
Yield: Yield was defined as the weight of each sample as a percentage of the weight of the fillet having skin.
Percentage of powder as a constituent: The percentage of powder as a constituent was measured according to the Japanese Agricultural Standards for kezuribushi. The percentage was obtained as follows: the sample of kezuribushi was sifted through a sieve having an opening of 850 um, as provided for by JIS Z 8801-1; the weight of the powder sifted through the sieve was divided by the weight of the sample before sifting, thereby obtaining the percentage of powder in the sample.
Unsalted soluble-solids (extract) content: The unsalted soluble-solids content (extract) was measured according to the Japanese Agricultural Standards for unsalted soluble-solids content (extract) as follows: a specified amount of hot-water extract of kezuribushi was put on an evaporating dish and was evaporated using a water bath so that the extract became a solid; the weight of the solid was measured, with said weight was deemed to be the weight of the total unsalted soluble-solids content (extract) (soluble-solids content); the salt content, which was separately measured, was subtracted from the total unsalted soluble-solids content (extract), so that the unsalted soluble-solids content (extract) was obtained (salt-free soluble-solids content); and the percentage of the unsalted soluble-solids content (extract) as a constituent was obtained based on an average moisture content of 15% by weight, because the moisture content of the samples was distributed from 13%-21% by weight, which means that the unsalted soluble-solids content (extract) percentage of the solid was deemed as 85% by weight.
Free-amino-acids content: The free-amino-acids content was determined as follows: levels of various amino acids, including free amino acids and ammonia, were measured according to Shokuhin Eisei Kensa Shishin, Rikagakuhen, (Guide for Food Sanitation Examination, Physicochemistry) published by the Japan Food Hygiene Association, by using an amino-acid analyzer (Model L-8500, manufactured by Hitachi, Ltd.); the amino-acids content was estimated based on an average moisture content of 15% by weight.
Inosinic acid content: Inosinic acid content was determined by High Performance Liquid Chromatography (Model LC-10A, manufactured by Shimadzu Corporation). HPLC analysis was carried out as follows: column: Model STR ODS-II (manufactured by Shimadzu Techno-Research, Inc.); eluent: 0.018 M Citric acid --- 0.025 M N, N diethylethanolamine (pH 4.4); flow rate: 0.9 mL/min.; and effluent monitoring: 254 nm (wavelength). The inosinic-acid content of each sample was first calculated as the IMP (inosine monophosphate: C₁₀H₁₃N₄O₈P) content, using IMP-Na₂-n Hydrate as the standard substance, and then the IMP content was converted to IMP content as the inosinic-acid content of each sample, based on an average inosinic-acid content of 15% by weight.
Inosine content: The inosine content was measured under the same conditions as the inosinic acid content; however, inosine was used as the standard substance, and then the obtained inosine content was converted to the inosine content of each sample, based on an average inosinic-acid content of 15% by weight.
Hypoxanthine content: The hypoxanthine content was measured under the same conditions as the inosinic acid content; however, hypoxanthine was used as the standard substance, and then the obtained hypoxanthine content was converted to the hypoxanthine content of each sample, based on an average inosinic-acid content of 15% by weight.

Test Results
The results of the tests are shown on Table 22 through Tables 27. The sign "-" included in Table 26 indicates that the level of free amino acids was below the limit of measurement. Set forth below are matters worthy of special mention.
--- The sake-kezuribushi obtained in Experimental Examples 2 and 3 tasted sweeter than that obtained in Experimental Example 1. This might be due to the use of seawater in the soaking-in-water treatment, in which sake-kezuribushi acquired a moderately salty taste (salt content of 0.5%-0.6%) due to salt in the seawater, which resulted in the sweet taste of the sake-kezuribushi.
--- The test results regarding Experimental Examples 2 and 3 show the following: even if the linear velocity of the flowing water was as low as 2 cm per minute, under the conditions that the temperature of water was 7 deg C plus minus 1 deg C, and the time for soaking was 10 minutes, the generation of the above described unpleasant odor could be prevented for up to 12 months, and good-quality sake-kezuribushi having a good flavor could be obtained.
--- The test results regarding Experimental Examples 4 and 5 show the following: if skinning was performed subsequent to shajuku or subsequent to the first heating step of smoking-and-drying, the fillets' yield decreased and the content of powder increased. If the skinning was performed subsequent to the second heating step of smoking-and-drying, the skinning work was difficult, and therefore skinning should be done before shajuku.
--- The test results regarding Experimental Examples 7-9 showed the following: if steaming was done instead of shajuku, generation of an unpleasant odor specific to sake-bushi was observed even when the fillets were processed under favorable conditions in other processes; if the temperature of water during shajuku was increased to 90 deg C, slight distortion (twist) or cracks in the meat of the fillets, and small void (empty) places in kezuribushi were generated, so that the finished products did not have enough umami; therefore, it is preferable that the upper limit of the temperature of the heated water be less than 90 deg C. The test results showed, moreover, that: if the total time required for shajuku exceeded 80 minutes, the meat of fillets was stretched undesirably , and the umami content in kezuribushi decreased (decrease in the unsalted soluble-solids content (extract) and free glutamic acid); the time for maintaining the non-elevated temperature after the fillets were put into the water should be less than 20 minutes; the time between the start of heating and the end of shajuku should be 60 minutes or less; and treatment suitable to salmon as raw materials should be performed in shajuku.
--- The test results regarding Experimental Examples 10-16 showed the following: the smoking-and-drying equipment used for manufacturing gyobushi, including katsuo-bushi, can be used in smoking-and-drying; in order to obtain sake-arabushi or sake-kezuribushi of good quality having good flavor, the conditions of smoking-and-drying specific to salmon as raw materials should be adopted; the preferable smoke wood is Japanese cherry wood; preferable temperatures for smoking-and-drying should be lower, by 5 deg C, than those used for gyobushi, including katsuo-bushi; and it is preferable that smoking-and-drying be performed during the sixth through eighth heating steps.
--- The test results regarding Experimental Examples 17 and 18 showed the following: if salmon raw materials having a lipids content of 4% or more by weight were used, defatting treatment by pressing the raw materials can be performed; the lipids content of sake-arabushi and sake-kezuribushi decreased due to the defatting, which caused deterioration of the quality of kezuribushi, including the presence of cracks, although the kezuribushi's flavor was good; and it is preferable that the lipids content of salmon materials should less than 4% by weight. (The values in the "lipids content" cells in the "after shajuku" column in Table 25, regarding of Experimental Example 18, are the values obtained after defatting was performed subsequent to shajuku.)
--- The test results regarding Comparative Examples 1 and 2 showed the following: if soaking-in-water was not done, the unpleasant odor specific to salmon could not be controlled; the obtained kezuribushi did not have a good flavor, having a strong astringent taste; and even if smoking-and-drying was done up to the eighth step, generation of an unpleasant odor could not be controlled.
--- The sake-kezuribushi of Comparative Example 3 had a strong unpleasant odor, and showed results that were quite different from those of the experimental examples in regard to almost all test items, including powder content, resilience of the sliced portions of kezuribushi, unsalted soluble-solids content (extract), level of free amino acids, inosinic acid content, inosine content, and hypoxanthine content. Accordingly, if Comparative Example 3 had used salmon raw materials that were the same as those of the experimental examples, the method of manufacturing, and the quality of, Comparative Example 3 products would have been completely different from those of Experimental Examples.

Claims

A method for manufacturing sake-arabushi that uses more than one type of salmon selected from salmon that have not gone upstream, female salmon going upstream during the period of egg collection or spawning, and male salmon going upstream during the period of ejaculation, with said method successively comprising:
(a) a pretreatment process in which a salmon is cut up so as to make a fillet having skin;
(b) a soaking-in-water treatment in which, after pretreatment, the fillet is soaked in clean water or water that contains salt of 5% or less by weight, and that is at a temperature between 20 deg C or less and the lowest temperature at which water does not freeze, with said fillet kept in the water for 5 minutes-30 minutes;
(c) a shajuku (soaking and denaturing in hot water) process in which, after soaking-in-water, the fillet is maintained in water of 60 deg C-80 deg C for 5 minutes-20 minutes, after which the water in which the fillet is soaked is heated, until the temperature of the fillet reaches 84 deg C or more but less than 90 deg C, for 30 minutes-60 minutes after the start of heating; and
(d) a smoking-and-drying process that includes: a first heating step called "ichibanbi," in which, after shajuku, the fillet is smoked and dried for 1 hour-9 hours at an ambient temperature of 80 deg C-85 deg C; a second heating step called "nibanbi," in which, after aging at a normal temperature subsequent to the first heating step, the fillet is smoked and dried for 1 hour-9 hours at an ambient temperature of 80 deg C-85 deg C; a third heating step called "sanbanbi," in which, after aging at a normal temperature subsequent to the second heating step, the fillet is smoked and dried for 1 hour-9 hours at an ambient temperature of 65 deg C-70 deg C; a fourth heating step called "yonbanbi," in which, after aging at a normal temperature subsequent to the third heating step, the fillet is smoked and dried for 1 hour-9 hours at an ambient temperature of 60 deg C-65 deg C; a fifth heating step called "gobanbi," in which after aging at a normal temperature subsequent to the fourth heating step, the fillet is smoked and dried for 1 hour-9 hours at an ambient temperature of 56 deg C-65 deg C; and a sixth heating step called "rokubanbi," in which, after aging at a normal temperature subsequent to the fifth heating step, the fillet is smoked and dried for the same amount of time and at the same temperatures as in the fifth heating step.
The method for manufacturing sake-arabushi according to Claim 1, and wherein between said soaking-in-water and shajuku the skins of the fillets are removed by skinning.
The method for manufacturing sake-arabushi according to Claim 1, and wherein during said soaking-in-water, the fillets having skin are soaked in clean water or water that contains salt of 5% or less by weight, and that is at a temperatures of 5 deg C-8 deg C for 7 minutes-14 minutes.
The method for manufacturing sake-arabushi according to Claim 1, and wherein during said soaking-in-water, the fillets having skin are soaked in clean water or water containing salt of 5% or less by weight in a soaking container, and clean water or water containing salt of 5% or less by weight is allowed to run over the surfaces of the fillets having skin at a linear velocity of 3 cm-10 cm per minute.
A method for manufacturing sake-kezuribushi, wherein sake-arabushi manufactured according to any of the preceding Claims is used as the raw material.