WO2008058844A1

WO2008058844A1 - A method for the production of medium-long life milk and an apparatus that carries out the method

Info

Publication number: WO2008058844A1
Application number: PCT/EP2007/061639
Authority: WO
Inventors: Settimio Coacci; Carlo Coacci
Original assignee: Zinco Di S. Coacci & C. S.A.S.
Priority date: 2006-11-16
Filing date: 2007-10-30
Publication date: 2008-05-22
Also published as: ITBO20060782A1; EP2099310A1

Abstract

A method provides for the production of medium-long life milk, with superior quality factors, because obtained from raw milk only, by only one processing cycle and only one heat treatment, bactofugation and titration steps. The method includes: heating of the raw milk up to a first temperature T1; skimming of the milk; bactofugation; further rising the milk temperature up to a second temperature T2 for a limited time, to obtain a microbe reduction for rendering the milk suitable for storage, for consumption purposes and in sterile containers, for at least two - three months; cooling and packaging of the so obtained milk.

Description

A METHOD FOR THE PRODUCTION OF MEDIUM-LONG LIFE MILK AND AN APPARATUS THAT CARRIES OUT THE METHOD

BACKGROUND OF THE INVENTION

The present invention relates to the technical milk dairy field, with particular reference to the apparatuses for the production of the UHT long life milk.

DESCRIPTION OF THE PRIOR ART Currently, a number of heat treatments are carried out on milk, from the milking moment up to the packaging in sterile containers, which result in diverse levels of reduction of the microbial activity, giving the final product a longer or shorter storability and particular nutritional and organoleptic factors. Among them, the UHT heat treatment includes heating the pasteurized milk to very high temperatures (above 135°C) for a time limited to few seconds, in order to destroy the microorganisms and deactivate the heat-resistant enzymes present therein; the resulting product has appreciable organoleptic and nutritional factors, and can be stored at ambient temperature in suitable aseptic packages for some months.

Generally, the raw, just milked milk is conveyed into suitable tanks, which are installed at the farm, and is kept there at a constant temperature of 4 - 5°C; every day or every two days the milk is moved to tank trucks

(insulated) and transferred to production centers (cheese factories, dairies), where it is stored in cisterns at a constant temperature (4°C) .

According to the European regulations, it must be subjected to a suitable heat treatment within 48-72 hours after having been milked; the chosen treatment is usually the pasteurizing, which includes: milk heating process, in order to eliminate dangerous microorganisms; and skimming operation, which allows to separate the high-fat part of milk from the low-fat part thereof, so as to obtain cream and whole, partially skimmed or skimmed milk. At this point, the pasteurized milk can be stored for further 48 - 72 hours before another heat treatment takes place, for example UHT.

In some cases, milk obtained from a pre-established mixture of lean milk (fat-free, obtained by skimming operation) with cream or whole milk, previously pasteurized, is subjected to the UHT treatment, in order to obtain UHT whole, partially skimmed or skimmed milk.

These heating processes (pasteurization, UHT) must be effected in a working environment, as required by the current regulations: for example, the pasteurization process can be effected with different time/temperature ratios (e.g. heating at 72°C for 15 seconds), as long as it remains within a delimited application interval.

Consequently, once treated and packaged, milk of the same origin (coming from the same cowshed) can have different organoleptic and biological factors, according to the heat treatments it has undergone. The heat effect, or damage to the milk, can be quantified by revealing analytical indexes, identified for this purpose, related to some substances present in the milk, in case of UHT milk, for example, it is especially lactulose and furosine; thus, their concentration gives the information about the quality of the final product, destined to be sold, since it allows to trace the treated milk "heat story", going back also to the technology used.

The enclosed Figure 1 is a schematic view of a known apparatus for the production of the UHT processed milk: the tank C contains pasteurized milk kept at constant temperature (for example at 4⁰C) and feeds a functional tank SF, of lower capacity; the milk is conveyed from here to a heat exchanger SCN (inlet IN-C) , where it is subjected to a given flow of heat, by direct or indirect heating, so as to reach high temperatures (above 135°C) for few seconds, and then cooled.

As known, the exchanger SCN includes a channel, which has a forward run RA and backward run RR; the latter are separated by a conductive wall, to allow the heat exchange between the coming fluid (milk) , aimed at getting heated, and the return one, aimed at getting cooled. A heat introduction unit UIC, functionally interposed between the forward run RA and the backward run RR, includes for example a steam injection system or a steam infusion system (direct milk heating method) or milk heating system by application, for example, of steam to some portions of the exchanger SCN channel (indirect milk heating method) .

The usual milk homogenization step, which occurs at about 80 - 90⁰C, has not been shown in Figure 1, for simplicity's sake.

Figure 2 shows, in a qualitative way, the milk time- temperature characteristic during the UHT heat treatment: as it can be seen therefrom, the milk remains at higher temperatures, approximately at 90⁰C for a time Δti, sufficient to eliminate pathogenic germs and to reduce drastically the bacterial charge, as it is known.

At the outlet OUT-C of the exchanger SC, the milk is conveyed for example to another functional tank SF, necessary to feed an associated unit UC, where the milk is packaged into aseptic containers; this way, the obtained milk can be preserved for at least two - three months at ambient temperature.

At present, the milk can be also subjected to more pasteurization treatments, aimed at lengthening its storability before the UHT process, this can occur more frequently in case of pasteurized milk imported from other states.

SUMMARY OF THE INVENTION

The main object of the present invention is to propose a newly conceived method for the production of medium-long life milk, which is aimed at obtaining a final product of confirmed quality, higher with respect to milk obtained by similar technologies of known type. Within this meaning, the aim is to achieve this object by providing a method, which includes a series of essential working steps for obtaining, from still raw milk, medium-long life milk, especially of the UHT type, subjected on the whole to a smaller heat stress with respect to methods of known type, with the same storage time and microbial killing obtained. Another object of the present invention is to propose a method, whose carrying out is relatively cheap with respect to the advantages to be obtained. A further object of the invention is to propose an apparatus for the production of medium-long life milk, in particular of the UHT processed type, which is newly conceived, reliable, functional and that allows obtaining a final product of higher quality than the product currently obtained with apparatuses of known type, since, on the whole, it is destined to be subjected to a smaller heat stress.

Another object of the present invention is to propose an apparatus, whose costs are relatively low with respect to the advantages to be obtained.

The above mentioned objects are obtained, in accordance with the contents of the claims, by a method for the production of medium-long life milk from raw milk, characterized in that it includes the subsequent steps: - heating said raw milk up to a first temperature; skimming the milk heated up to said first temperature, to separate a pre-selected quantity of fat; further rising the temperature of the so obtained milk, up to a second temperature, for a pre-selected time, so as to reduce microbes and make said milk suitable for storage, for consumption purposes and in sterile containers, for at least two weeks; cooling said milk; and packaging the milk into said sterile containers. The above mentioned method is carried out by an apparatus for production of medium-long life milk, including a tank for containment of raw milk, the apparatus being characterized in that it further includes: a first unit for heating the milk, coming from said tank, up to a first temperature; a unit, arranged functionally in cascade with said first unit, for skimming said milk, heated to said first temperature, with consequent separation of a pre-selected quantity of fat; a second unit, in turn arranged functionally in cascade with said skimming unit, for further rising the temperature of the milk obtained by skimming up to a second temperature for a certain time, so as to reduce microbes and make said milk suitable for storage, for consumption purposes, for at least two weeks; and a unit for packaging milk, connected functionally in cascade to said second unit.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristic features of the invention, not appearing from has been just said, will be better pointed out in the following description, in accordance with the contents of claims and with help of the enclosed figures, in which: - Figure 1 is a functional block diagram of a known apparatus for the production of UHT milk from pasteurized milk;

Figure 2 shows, in a qualitative way, a c, which describes a milk UHT heat treatment, from pasteurized milk at 4°C;

Figure 3 shows, in a qualitative way, a temperature- time feature, which describes a UHT heat treatment of milk obtained according to the invention, from raw milk at 4°C; - Figure 4 is a functional block diagram of the apparatus proposed by the present invention, according to a first embodiment;

Figure 5 is a schematic, enlarged view of a particularly significant element of Figure 4; - Figure 6 is a functional block diagram of the apparatus proposed by the present invention, according to another embodiment;

BEST MODES OF CARRYING OUT THE INVENTION Having regard to Figure 4, the reference C indicates a tank containing raw milk at a constant temperature, for example 4°C, not yet heat treated, i.e. not yet subjected to any heating process, and the reference SF indicates functional tanks, situated in some points of the proposed apparatus, in which functional introduction can be required for the plant good operation, as known to those skilled in the field.

In the example shown in Figures 4, 5, the reference SC indicates a heat exchanger, which is connected to the functional tanks SF by conventional inlet IN-C and outlet OUT-C, in turn connected respectively to a tank C and to the unit UC of known type for milk packaging; said exchanger SC is different from the known one SCN, described in Figure 1, in that it includes, in a portion of the forward run, a deviation of the whole fluid (milk) outward of the exchanger SC, through an additional outlet OUT-A and a subsequent introduction of the fluid downstream, along the same forward run, through an additional inlet IN-A. Within this meaning, a first forward run RA_x is defined, included between the conventional inlet IN-C and the additional outlet OUT-A, along which the milk is aimed to get heated up to a first temperature T₁ (see below), a short inactive section TI (indicated with a broken line and present only in case, in which the exchanger SC is obtained by adapting of a pre-existing exchanger, of known type SCN), and a second forward run RA₂, originating from the first additional inlet IN-A.

A heat introduction unit UIC, known in itself, situated functionally between the second forward run RA₂ and the backward run RR, includes for example a steam injection system or a steam infusion system (direct milk heating method) or by a system of milk heating by application for example, of steam to some portions of the exchanger SC channel (indirect milk heating method) .

Functional tanks SF are connected to the additional outlet OUT-A and to the additional inlet IN-A of the heat exchanger SC. The reference US indicates a skimming unit of known type, which receives at its inlet I-US the milk heated to the first temperature I₁, coming from the additional outlet OUT-A, and supplies at the outlet, from one side, milk containing a prefixed percentage of fat, coinciding with whole, partially skimmed or skimmed milk, and, from the other side, exceeding fat aimed at supplying a unit UPP for the production of cream, likewise of known type; which is obtained in known way, for example by a separating device S, that separates the high-fat part of milk from the low-fat part, and a titrator device T, that allows to recombine the lean milk with a part of fat according to prefixed percentage, to obtain whole, partially skimmed or skimmed milk. The reference B indicates a device of known type, for the bactofugation of the whole, partially skimmed or skimmed milk, coming from the outlet U-US of the skimming unit US.

The operation of the apparatus proposed by the present invention will be described in the following, with constant reference to the qualitative time-temperature characteristic of Figure 3. The raw milk in the inlet of the heat exchanger SC (conventional inlet IN-C) is conveyed along the first forward run RA₁, along which it is heated up to a first temperature T_x, included within a range of 50 - 60⁰C. At this temperature, the milk goes out of the heat exchanger SC and feeds the skimming unit US through the functional tank SF; the milk going out of the skimming unit US (U-US outlet in Figure 4), whole, partially skimmed or skimmed, is sent to the inlet of the bactofugation device B, which, as it is known, acts as a certain destroyer of the microbial charge contained in the milk, through a centrifugal process.

During the separation, titration and bactofugation steps, the milk is not subjected to any heat treatment and it can be supposed to be maintained substantially at the same first temperature I₁.

The milk leaving the bactofugation device B and the associated functional tank SF is conveyed again into the heat exchanger SC through the second forward run RA₂, where, before reaching the heat introduction unit UIC, it is heated again up to a temperature of, for example, 90⁰C.

The UIC unit, as already said, of known type, causes a rapid rise of the milk temperature up to a second temperature T₂, for example of 140⁰C, for a very limited time Δt₂, followed by a rapid cooling up to a temperature, near, for example to 90⁰C.

As it can be deduced, comparing the Figures 2, 3, in this step the heat delivery (which occurs in direct or indirect way, Figure 3) is much more moderate (Δt₂<Δti) with respect to the one occurred with the known exchanger SCN (Figure 2). The heat is delivered inside the UIC unit, taking in consideration the microbial killing, obtained by the bactofugation, and the object of obtaining safe food, which can be stored in sterile packages for at least two - three months (UHT milk) , according to the provisions of the regulations.

Consequently, the apparatus, proposed by the invention, delivers advantageously less heat with high temperatures with respect to prior art technologies.

The milk leaving the UIC unit has the temperature of, for example, 90⁰C; it is conveyed along the backward run RR of the heat exchanger SC, where it is further cooled, so as to be conveyed into the functional tank SF and then packaged into sterile containers of the packaging unit UC

The above description characterizes the method for the production of medium-long life milk, likewise proposed by the present invention, including the following steps, in the order: heating the raw milk up to a first temperature I₁; - skimming the heated milk, to separate it from a preselected quantity of fat, to obtain for example whole, partially skimmed or skimmed milk, thus completing the pasteurization process; bactofugation of the so obtained milk, so as to obtain a certain microbial presence reduction; heating of the milk up to a temperature of, for example, 90⁰C; further rapid heating of the milk (UHT) up to the second temperature T₂, for example of 140⁰C, followed by a rapid cooling of the milk up a temperature of about, for example 90⁰C; subsequent cooling of the milk, including a homogenization step of known type, and its packaging into sterile containers.

It is possible to produce cream, in known way, from the exceeding fat obtained by the milk skimming step.

As already said, the milk rapid heating up to the second temperature T₂ is carried out in order to complete the microbial presence reduction, according to regulatory standards, so as to obtain safe food, which can be stored in sterile packages for at least two - three months; due to the previous bactofugation operation, operated mechanically, reducing in itself in substantial way the microbial charge, the subsequent required heat delivery is very moderate with respect to the prior art (actually, it continues for a very limited time Δt₂) , and consequently, so is the resulting heat damage. It is pointed out that the heat delivery is really lower than the one necessary with a normal direct or indirect heating method, if the bactofugation should not be provided. The resulting considerable advantage lies in a much lower milk heat stress with respect to what happens with known processes, in accordance with registered low lactulose and furosine values, which prove the high quality of the so obtained milk, from the organoleptic and nutritional point of view.

Therefore, with respect to the known technologies, a drastic and decisive reduction of the heat stress, to which the UHT processed milk is subjected, is obtained, with an equal microbial reduction effect. The smaller heat damage of the milk allows to obtain high quality food, of best organoleptic and nutritional factors, as, for that matter, it would be possible to notice by comparing the indexes of the heat damage, lactulose and furosine of the UHT processed milk obtained with traditional technology, to the ones of the milk obtained by the present invention . Moreover, advantageously, the pasteurization process is only one and is performed in the same apparatus, in which the UHT treatment is performed, from the raw milk; whereas, in prior art, the milk could have been subjected to further pasteurization treatments in different places, and was transferred between the apparatuses for milk pasteurization and apparatuses for UHT process, and consequently even many days might pass from the milking step to the final packaging one.

Obviously, this allows to plan and organize the production process in a more convenient way, as well as to reduce general costs (among which the transport costs) and production time.

Moreover, further important advantages are obtained, connected indirectly with this aspect: if before, using the known methods, the milk pasteurization step was followed by the cooling up to 4⁰C, then by the milk transfer to the storage tank C and then to the UHT treatment apparatus, and afterward the heat treatment application to the pasteurized milk, beginning from a temperature of 4⁰C, now, according to the invention, the milk heating up to the first temperature I₁, during which the skimming occurs to complete the pasteurization process, is followed by the subsequent bactofugation and heat UHT treatments, beginning from the same first temperature T_x.

This causes a further, considerable reduction of the heat stress, to which the milk is subjected during its production cycle, and moreover, a significant energy saving .

A further advantage of the invention lies in the possibility to obtain the apparatus proposed by the present invention by easy adapting of apparatuses of known type, like the one shown in Figure 1; actually, in this case, it is possible to use the exchanger SCN of known type, with some simple changes applied thereto, thus making it equivalent to the heat exchanger SC shown in Figures 4, 5. Thus, the pre-existing apparatuses can be modified at small costs, so as to carry out the present invention.

Moreover, the proposed apparatus is not only aimed at the production of the UHT long life milk; it is possible, by controlling the heat delivery by the UIC unit (with both direct and indirect heating) , to obtain milk, that can be stored in sterile packages for few weeks, for example, at least two.

Another advantage of the invention lies in the fact that it has defined a functional, reliable apparatus, that can be easily obtained from the pre-existing apparatuses by simple adapting operations.

A further advantage of the present invention lies in the fact, that it has conceived an apparatus for the production of medium-long life milk, whose costs are relatively low with respect to the obtained advantages.

A further advantage of the present invention lies in the fact, that it has created a method for the production of medium-long life milk, which is newly conceived and which allows to obtain a final product of confirmed higher quality with respect to the similar technologies of known type. This has been achieved by having contrived a method, which includes a sequence of essential working steps, that obtain, beginning from raw milk, medium-long life milk, in particular of the UHT processed type, which is subjected on the whole to a lower heat stress with respect to the methods of known type, with the same storage time and microbial reduction obtained. This appears clear from experimental registering effected on the indexes of the UHT processed milk heat damage, lactulose and furosine, which confirm better organoleptic and biological characteristics of the milk obtained according to the present method, in comparison with the one obtained according to known technologies.

A further advantage of the present invention lies in the fact, that it has defined a method for the production of medium-long life milk, whose essential steps allow, with respect to the solutions of known type, to obtain a considerable energy saving, because the pasteurization, bactofugation and the final UHT treatment steps take place one after another during the same production cycle. A yet further advantage of the present invention lies in the fact, that it has defined a method, that is carried out at the relatively limited costs with respect to the obtained advantages.

Otherwise, the bactofugation device B can be situated upstream of the skimming unit US (this variant has not been shown in Figures) , instead of downstream; then, the device B can be substituted with a milk microfiltration device of known type, not shown in the enclosed Figures, situated upstream or downstream of the skimming unit US . Likewise, the method proposed by the invention can include the bactofugation step before the milk skimming; the bactofugation step, provided before or after skimming, can be likewise substituted with a milk microfiltration step, of known type.

As an alternative to the proposed heat exchanger SC, as already said, obtainable also from a known exchanger SCN by applying suitable adaptations, it is possible to provide, in the same way, a first heating unit Ui, functionally interposed between the functional tanks SF, associated to the tank C and the skimming unit US, respectively, for heating the milk up to the first temperature T₁, and a second unit U₂, situated downstream of the bactofugation device B and aimed at carrying out the same heat treatments as described above, which before were carried out in the second forward run RA₂, inside the UIC unit and inside the backward run RR. The first unit U₁ and the second unit U₂, functionally equivalent to the heat exchanger SC, have not been shown in the enclosed figures.

An embodiment has been shown in Figure 6; it differs from the one described with reference to Figures 4, 5 in that it does not have the bactofugation device B. In this case, the heat delivery at elevated temperatures (higher than 90⁰C), of intensity sufficient to eliminate the milk bacterial charge (as already said, in accordance with the regulations relative to the UHT treatment, in order to obtain food storable for at least two - three months), must be certainly higher than the one obtainable according to the first embodiment.

Another method for the production of medium-long life milk is defined from what has been said in relation to the embodiment, likewise remaining within the protective scope of the present invention, and including as follows: heating the raw milk up to a first temperature T₁; skimming the heated milk, to separate it from a preselected quantity of fat; so as to obtain whole, partially skimmed or skimmed milk, thus completing the pasteurization process; - heating of milk up to a temperature of, for example, 90⁰C; further heating of milk (UHT) , up to a second temperature T₂, for example of 140⁰C, followed by its cooling up to a temperature of about, for example, again 90⁰C: the duration of this step is substantially equal to Δti; a subsequent cooling of milk, including a homogenization step of known type, and its packaging into sterile containers. This embodiment of the apparatus, and the resulting working steps, differ from the first embodiment in that they include a longer UHT heat treatment, at high temperatures, to which corresponds a bigger heat delivery, with the same microbe reduction obtained; besides this, all the advantageous technical-functional characteristic features of the invention, pointed out above, remain valid.

It is understood that what above, has been described as a not limiting example, therefore possible practical- application variants remain within the protective scope of the invention as described above and claimed below.

Claims

1. A method for the production of medium-long life milk from raw milk, characterized in that it includes the subsequent steps: heating said raw milk up to a first temperature (Ti) ; skimming the milk heated up to said first temperature (Ti) , to separate a pre-selected quantity of fat; further rising the temperature of the so obtained milk, up to a second temperature (T₂) , for a pre-selected time, so as to reduce microbes and make said milk suitable for storage, for consumption purposes and in sterile containers, for at least two weeks; cooling said milk; and - packaging the milk into said sterile containers.

2. A method, according to claim 1, including also a milk centrifugation step, after said skimming step, so as to obtain a certain microbe reduction.

3. A method, according to claim 1, including also a milk centrifugation step, after said raw milk heating up to a first temperature (T_x) , so as to obtain a certain microbe reduction.

4. A method, according to claim 2 or 3, wherein said centrifugation step is substantially a bactofugation.

5. A method, according to claim 1, including also milk microfiltration .

6. A method, according to claim 1, wherein the milk is further heated up to a second temperature (T₂) for a preselected time, so as to reduce microbes in order to make said UHT processed milk suitable for storage, for consumption purposes and in sterile containers, for more weeks .

7. A method, according to claim 1 or 3, wherein said first temperature (I₁) is in the range of fifty to sixty degrees centigrade.

8. An apparatus for production of medium-long life milk, including a tank (C) for containment of raw milk, the apparatus being characterized in that it further includes : a first unit (Ul) for heating the milk, coming from said tank (C) , up to a first temperature (T₁) ; a unit (US) , arranged functionally in cascade with said first unit (Ui) , for skimming said milk, heated to said first temperature (T_x) , with consequent separation of a pre-selected quantity of fat; a second unit (U₂) , in turn arranged functionally in cascade with said skimming unit (US), for further rising the temperature of the milk obtained by skimming up to a second temperature (T₂) for a certain time, so as to reduce microbes and make said milk suitable for storage, for consumption purposes, for at least two weeks; and a unit (UC) for packaging milk, connected functionally in cascade to said second unit (U₂) .

9. An apparatus, according to claim 8, further including a centrifugal device, functionally interposed between said skimming unit (US) and said second unit (U₂) .

10. An apparatus, according to claim 8, further including a centrifugal device, functionally interposed between said first heating unit (Ui) and said skimming unit (US) .

11. An apparatus, according to claim 9 or 10, wherein said centrifugation device is constituted by a bactofugation device (B) .

12. An apparatus, according to claim 8, further including a milk microfiltration device.

13. An apparatus, according to claim 8, wherein said first heating unit (Ui) and said second unit (U₂) are functionally integrated in the same heat exchanger (SC), which: is fed by means of said tank (C) at its conventional inlet (IN-C); communicates with said packaging unit (UC) at its conventional outlet (OUT-C) ; and has also an additional outlet (OUT-A) and an additional inlet (IN-A) for the connection with said skimming unit (US) .

14. An apparatus, according to claim 8 or 13, wherein said second unit (U₂) includes a unit (UIC) for direct or indirect introduction of heat into the milk, so as to heat it up to said second temperature (T₂) for a certain time.

15. An apparatus, according to claim 8, wherein said first temperature (T₁) is in the range from fifty to sixty degrees centigrade.