WO2009131282A1

WO2009131282A1 - Method for production of beer using unhulledand rice and rice beer thereof

Info

Publication number: WO2009131282A1
Application number: PCT/KR2008/006178
Authority: WO
Inventors: Kwang Geun Lee; Seung Ju Lee; Seung Joo Lee; Yong Sun Lee; Pil Woo Nam; Sung Ki Hyun
Original assignee: Dongguk University Industry-Academic Cooperation Foundation
Priority date: 2008-04-23
Filing date: 2008-11-25
Publication date: 2009-10-29
Also published as: KR20090112057A; KR101002740B1

Abstract

The present invention relates to a method for producing a rice beer and a rice beer produced thereby, the method comprising the steps of: immersing mixed grains of unhulled rice and malt in water at a temperature ranging from 48 0C to 53 0C to release saccharifying enzymes; gelatinizing and saccharifying the grains at a temperature ranging from 62 0C to 68 0C inactivating the saccharifying enzymes and filtering the saccharified material to obtain a wort; adding hops to the wort and boiling the hopped wort; and adding yeast to the wort and fermenting the wort. In the method, the rice beer can be produced without using a special enzyme, and thus the production cost can be reduced and the content of rice in the rice beer can be increased. The produced rice beer combines the inherent flavor of rice bran with the nutty taste of white rice and the flavor of hops and barley, and thus has excellent sensory characteristics.

Description

METHOD FOR PRODUCTION OF BEER USING UN- HULLED AND RICE AND RICE BEER THEREOF

Technical Field

[1] The present invention relates to a method for producing a rice beer and a rice beer produced thereby, and more particularly to a method for producing using enzymes released from rice bran and malt without adding a special enzyme and to a rice beer produced thereby which is rich in nutrients. Background Art

[2] Beer is a fermented alcoholic drink which is being widely drunk mainly by young people in Korea. Beer is generally produced by a two-step fermentation process which comprises germinating barley or wheat, saccharifying the starch of barley or wheat into glucose by various enzymes, including saccharifying enzymes produced during the germination, adding hops to the saccharified material, boiling the hopped material to prepare a wort, adding brewer's yeast to the wort to produce alcohol, and aging the alcohol while allowing carbonic acid gas to remain.

[3] Meanwhile, in the production of oriental alcoholic wines excluding compounded alcoholic wines, grain alcoholic wines (unrefined rice wine, refined rice wine, clear rice wine, etc.) are conventionally produced with a grain raw material (starchy raw material) using, as a fermenting agent, either nuruk, which is a starter for preparing Korean alcoholic drinks, or koji which is a recently developed improved nuruk. The produced grain alcoholic wines are drunk as they are, or distilled to produce distilled liquors (distilled Soju and diluted Soju).

[4] Meanwhile, Korean Patent No. 10-0651266 discloses a technology relating to a beer which targets young people and is prepared by adding rice so as to combine the characteristics of Korean traditional wines with the characteristics of oriental beer. The disclosed technology has problems in that, because a special enzyme is added from the outside, a high production cost is required, and in that the rice-derived flavor is not specially added.

Disclosure of Invention

Technical Problem

[5] It is, therefore, an object of the present invention to provide a production method enabling a rice beer having an excellent flavor to be produced without adding a special enzyme and a rice beer produced thereby. Technical Solution

[6] To achieve the above object, the present invention provides a method for producing a rice beer, the method comprising the sequential steps of: immersing mixed grains of unhulled rice and malt in water at a temperature ranging from 48 ⁰C to 53 ⁰C to release saccharifying enzymes; gelatinizing and saccharifying the grains at a temperature ranging from 62 ⁰C to 68 ⁰C; inactivating the saccharifying enzymes and filtering the saccharified material to obtain a wort; adding hops to the wort and boiling the hopped wort; and adding yeast to the wort and fermenting the wort.

[7] The present invention also provides a rice beer produced by the above method for producing the rice beer.

[8]

[9] Hereinafter, each step of the production method according to the present invention will be described in detail.

[10] Step 1 : a step of immersing mixed grains of unhulled rice and malt in water at a tem- perature between 48 and 53 ⁰C to release saccharifying enzymes

[11] Step 1 is a step of immersing mixed grains of unhulled rice and malt in water at a temperature between 48 and 53 ⁰C to release saccharifying enzymes.

[12] The distribution of nutrients in unhulled rice is about 66% in the rice embryo, about

29% in the rice bran and about 5% in white rice. Thus, unhulled rice is richer in nutrients than polished rice (white rice), and the rice bran comprising the rice embryo comprises about 45% carbohydrate, about 25% dietary fiber, about 16% fat, about 14% protein and a trace amount of vitamins and minerals including calcium, magnesium and phosphorus and contains a large amount of enzymes required for saccharification.

[13] The present invention is characterized by the use of unhulled rice and has technical characteristics distinguishable from those of some beers produced by adding rice as a sub-material. Specifically, because saccharifying enzymes contained in rice bran perform the gelatinization and saccharification of starch in corporation with saccharifying enzymes contained in malt, the saccharification process in the present invention can be carried out at a temperature lower than those in general beer production methods in which the saccharification process is carried out only using malt. The need to separately add saccharifying enzymes from the outside in order to facilitate saccharification is eliminated. In addition, because unhulled rice is used, components which are not contained in polished rice increase the aroma components of beer, whereby a beer having an excellent flavor can be produced.

[14] Meanwhile, malt is a barley grain obtained by germinating unhulled barley under the action of moisture, heat and oxygen, contains saccharides such as starch, vitamins and various enzymes and imparts the inherent flavor of malt to beer. Malt releases enzymes required for saccharification and various other enzymes to degrade proteins into amino acids and degrades the starch of rice bean into fermentable glucose in corporation with the saccharifying enzymes. [15] Meanwhile, in the present invention, mixed grains of unhulled rice and malt are immersed in water at a temperature ranging 48 ⁰C to 53 ⁰C to release saccharifying enzymes. In this case, the release of enzymes can be efficiently achieved and the activity of protease can increase to produce amino acids showing a nutty taste.

[16] Meanwhile, the content of water is preferably in the range of 500-600 wt% based on the amount of the mixed grains of unhulled rice and malt, but is not limited to a particular range.

[17] Meanwhile, the weight ratio of unhulled rice and malt in the mixed grains is preferably in the range of 45-55 wt% unhulled rice: 55-45 wt% malt, but is not limited to a particular range. If unhulled rice is used in an amount of less than 45 wt%, the flavor of the resulting beer will be poor, and the content is more than 55 wt%, the product characteristics of the resulting beer will not be sufficiently exhibited, the amount of malt added is relatively reduced.

[18] Meanwhile, the immersion time is preferably in the range of 12-18 minutes, but is not limited to a particular range. In this case, saccharifying enzymes can be economically released from unhulled rice and malt.

[19]

[20] Step 2: a step of gelatinization and saccharification at a temperature of 62 ⁰C to 68 ⁰C after immersion

[21] Step 2 is a step of gelatinizing and saccharifidying the grains at a temperature of 62

⁰C to 68 ⁰C.

[22] As used herein, the term "gelatinizing" means that water is added to a starch consisting of dense particles and the temperature of the starch is increased to swell the starch, thus creating the space between the particles and forming the colloidal state. In the present invention, the penetration of enzymes into gelatinized starch can be more easily achieved compared to the penetration into raw starch to increase the availability of the starch, whereby the starch can be easily converted into fermentable glucose.

[23] Meanwhile, in the present invention, gelatinization and saccharification processes are carried out at a temperature lower than a gelatinization temperature of about 70 ⁰C which is applied in the prior art method for producing beer. In this case, saccharifying enzymes are present in a sufficient amount, because they are derived from not only malt, but also rice.

[24] Also, after the gelatinization process, the saccharification process is carried out by a special step of lowering the temperature of the grains. In the present invention, the gelatinization process is carried out at a temperature of 62 ⁰C to 68 ⁰C which is lower than the conventional gelatinization temperature, and thus a separate saccarification process is not additionally designed and the saccharification process can be carried out at the gelatinization temperature. [25] Also, because the gelatinization process can be carried out at a low temperature as described above, the volatility of flavor components can be reduced, so that the flavor components can be captured in a relatively large amount.

[26] Meanwhile, the time of gelatinization and saccharification is preferably in the range of 100-140 minutes, but is not limited to a particular range. In this case, the gelatinization and saccharification process is carried out in a cost-effective way.

[27] Meanwhile, starch is converted into fermentable glucose through the saccharification process, and as used herein, the term "fermentable glucose" refers to a glucose which can be used by yeast in a metabolic process. In the present invention, yeast intakes fermentable glucose to produce the alcohol and carbon dioxide required for beer.

[28]

[29] Step 3: a step of inactivating saccharifying enzymes and filtering the saccharified material after gelatinization and saccharification

[30] Step 3 is a step of inactivating saccharifying enzymes and filtering the saccharified material after gelatinization and saccharification. The inactivation of the saccharifying enzymes is preferably carried out at a temperature of 72 ⁰C to 78 ⁰C for 10 minutes to 20 minutes, but the inactivation conditions are not limited to particular conditions.

[31] Meanwhile, in the present invention, the shells of unhulled rice and malt are removed through filtration, and thus the precipitation of impurities during the production of beer can be prevented. In this case, the filtration process is preferably carried out by transferring the wort, in which the saccharifying enzymes have been inactivated, into a filter tank, and then allowing the transferred wort to stand in the filter tank. The filtration process is preferably carried out until a clear filter is obtained.

[32]

[33] Step 4: a step of adding hops to the filtered wort and boiling the wort

[34] Step 4 is a step of adding hops to the filtered wort and boiling the wort. In the boiling process, the wort is concentrated, while the bitter components and aroma of hops are leached, coagulable proteins or tannic materials are deposited, and the activity of enzymes is inactivated.

[35] Hops (humulus lupulus, L) which are used in the present invention are a perennial dioecious climbing plant belonging to the family Cannabinaceae and are used as a material for beer. Hops include lupulin comprising humulen, myrcene, humulon, lupulon, a hop resin, etc. Lupulin in hops functions to cause its unique flavor and bitter taste which impart a distinctive flavor and pleasant bitter taste to beer and exhibit antibiotic, sedative and antiseptic effects, thus increasing the storage stability of beer. Furthermore, the tannins contained in hops function to impart a bitter taste to beer in the same manner as lupulin and are balanced by the good taste of barley, and therefore, act to decrease a greasy feeling when taken along with greasy food. [36] Meanwhile, in the present invention, when the filtrate starts to boil, bitter hops are added to the filtrate which is then boiled for 60-120 minutes in order to sufficiently impart the aroma and taste of bitter hops to beer. Also, aroma hops are preferably added at 10-20 minutes before the end of boiling.

[37] Meanwhile, after completion of the boiling process, the sugar content of the wort is preferably in the range of 11 to 12 Brix, but is not limited to a particular range.

[38] Meanwhile, the inventive method for producing the rice beer preferably additionally comprises, after the boiling step, a step of removing the precipitate.

[39]

[40] Step 5: a step of adding yeast and fermenting the wort after boiling

[41] Step 5 is a step of adding yeast and fermenting the wort after boiling.

[42] Yeast grows and propagates using fermentable glucose contained in the wort while producing the alcohol and carbon dioxide required for the production of beer.

[43] Meanwhile, a method for carrying out the fermentation of the wort preferably comprises the steps of primarily fermenting the wort at a temperature of 12-18 ⁰C for 6-8 days to an alcohol content of 3-4%; and secondarily fermenting the wort at 0-2 ⁰C for 2-3 weeks to an alcohol content of 4-5%, but is not limited to a particular method. In this case, alcohol and carbon dioxide are suitably blended, thus producing a beer having an excellent flavor.

[44] Meanwhile, the present invention provides a rice beer produced according to the above method for producing the rice beer.

[45] Because the rice beer of the present invention is produced using unhulled rice as a main raw material and has a high rice content, it combines the inherent flavor of rice bran with the nutty taste of white rice and the flavor of hops and barley, and thus has excellent sensory characteristics.

Advantageous Effects

[46] As described above, in the inventive method for producing the rice beer, unhulled rice is added such that saccharifying enzymes can be released from rice bran, thus increasing usable saccharifying enzymes. Thus, the gelatinization and saccharification of starch can be performed at the same time, and the saccharification process can be carried out at a relatively low temperature. Also, because the rice beer of the present invention is produced using unhulled rice as a main raw material, it is richer in nutrients than polished white rice. In addition, the rice beer of the present invention has excellent sensory characteristics, because the inherent flavor of rice bran, the nutty taste of white rice and the flavor of hops and barley are harmonized with each other. Best Mode for Carrying out the Invention

[47] Hereinafter, the present invention will be described in further detail with reference to the following examples. However, the scope of the present invention is not limited only to these examples and encompasses the modification of technical ideas equivalent to the examples.

[48]

[49] Example 1: Production of beer using unhulled rice (unhulled rice: malt= 50:50)

[50] Each of unhulled rice and malt was crushed, and 2 kg of the crushed unhulled rice was mixed with 2 kg of the crushed malt. 22 L of brewing water corresponding to about 5.5 times the amount of the mixed grains of the crushed unhulled rice and the crushed malt was added to a brewing tank and heated to 53 ⁰C. Then, 4 kg of the mixture of the crushed unhulled rice and the crushed malt was added to the brewing water, and the temperature of the brewing water was maintained at 50 ⁰C for 15 minutes to release enzymes required for saccharification.

[51] After the enzymes were released, the temperature of the brewing water was increased to 65 ⁰C. At that temperature, the starch of the unhulled rice was gelatinized for about 120 minutes, while a saccharification process of converting rice starch and malt starch into fermentable glucose was carried out. After the saccharification was carried out, an iodine test was carried out to check the degree of saccharification. Then, the saccharified material was heated to 75 ⁰C, and the saccharifying enzymes were inactivated, thus stopping the saccharification process.

[52] The obtained mash was transferred into a filtration tank, in which the mash was allowed to stand and a filter layer was produced using husks. In the filtration process, the turbid filtrate was returned to the filtration tank and filtered therein, until a clear filtrate was obtained. After the clear filtrate was obtained, it was transferred into a boiling tank and boiled therein at about 100 ⁰C for 90 minutes. When the filtrate reached a temperature of 95 ⁰C or above, it started to boil, and at this time, 4 g of bitter hops were added. At 15 minutes before the end of the boiling, 4.5 g of aroma hops were added. After completion of the boiling process, the sugar content of the wort was 12 Brix, and the boiled wort was allowed to stand for a given period of time. Then, the sludge including coagulated proteins was removed by precipitation for 15 minutes using centrifugation (a whirlpool process). After completion of the precipitation process, the wort was cooled to 18 ⁰C using a heat exchanger and transferred into a fermentation tank. When about half of the wort was transferred into the fermentation tank, previously activated yeast was introduced into the fermentation tank.

[53] The activated yeast was obtained by adding 40 g of dry yeast to water and activating it at 24 ⁰C for 24 hours. After the wort was completely transferred into the fermentation tank, it was primarily fermented for 1 week while maintaining the temperature of the fermentation tank at 15 ⁰C. During the primary fermentation period, the pressure of gas in the fermentation tank was maintained at about 1.5-2 psi, and after completion of the primary fermentation, the beer had an alcohol content of about 4%. After completion of the primary fermentation, the temperature of the fermentation tank was lowered to 1 0C and maintained at that temperature for 1 day, and then the yeast was removed. Then, the wort was secondarily fermented while maintaining the temperature of the fermentation tank at 1 ⁰C. The secondary fermentation was carried out for 2 weeks, and after completion of the secondary fermentation, the beer had an alcohol content of 4.5%. Mode for the Invention

[54] Comparative Example 2: Production of beer using rice (white rice: malt= 50:50^s)

[55] A beer was produced using white rice in the same manner as in Example 1, except that white rice was used instead of unhulled rice (the mixing ratio of white rice to malt was 50:50).

[56]

[57] Test Example 1 : Analysis of flavor components of beer

[58] The flavor components of the beers produced in Example 1 and Comparative

Examples 1 and 2 were analyzed.

[59] The extraction of flavor components from the beers was performed using a solvent- assisted flavor evaporation (SAFE) apparatus. 1-dodecanol was used as an internal standard, and 400 μJl of 1-dodecanol was diluted in 2 ml of dichloromethane as a solvent. 5 jΛ of the internal standard dilution was added to 100 ml of the beer sample to be analyzed, and flavor components were extracted from the beer sample using the SAFE apparatus.

[60] The internal pressure of the SAFE apparatus was reduced, and the prepared beer sample was placed in a distillation flask and heated to 45 ⁰C in a water bath. When the beer sample was heated under reduced pressure, the flavor components were distilled, and the distilled components were cooled and captured by a flask opposite to the distillation flask, whereas the non-volatile components remained in the distillation flask. The cooled and captured flavor components were dissolved at room temperature, and then transferred into an Erlenmeyer flask together with 50 ml of dichloromethane and stirred for 1 hour so as to be absorbed into dichloromethane. The stirred material was separated into a dichloromethane layer and a water layer using a separatory funnel, and sodium sulfate was added to the separated dichloromethane layer. Then, the dichloromethane layer was stored in a refrigerator at 5 ⁰C for 12 hours to remove the remaining water. To the flask from which water has been removed and which contained the sample, a vigorous column was connected, and the sample was concentrated to a volume of 1 ml at 50 ⁰C, and then concentrated to 0.4 ml by charging nitrogen gas. [61] The analysis of the separated flavor components was performed using GC-MS. In the

GC analysis, a DB-wax was used, the injector temperature was maintained at 250 ⁰C, the oven temperature was maintained at 50 ⁰C for 2 minutes, elevated to 200 ⁰C at a rate of 3 °C/min, and then maintained at 250 ⁰C for 10 minutes, helium was used as a carrier gas, and the 1 μJl of the sample was injected in the splitless mode.

[62] The MS analysis for the identification of the flavor components was performed in the following conditions: MS ionization voltage: 70 eV; source temperature: 280 ⁰C, and mass spectrum range: 50-550 m/z. The flavor components were identified by comparing authentic compounds with the Kovats gas chromatographic retention index I, and then comparing the mass spectrometry fragmentation pattern (Willy 6th edition MS spectra library) of each component with those of authentic components.

[63] The amount of the flavor components was expressed as the ratio of the peak area of each component to the peak area of 1-dodecanol used as the internal standard.

[64] Table 1

[Table 1] [Table ]

[65] *Peak area of each compound/Peak area of Internal standard [66] The flavor components of the rice beer produced using mixed grains of unhulled rice: malt= 50:50 (Example 1).

[67] Table 2

[Table 2] [Table ]

[68] *Peak area of each compound/peak area of internal standard [69] The flavor components of beer containing no rice (general beer: Comparative Example 1).

[70] Table 3

[Table 3] [Table ]

[71] *Peak area of each compound/peak area of internal standard [72] The flavor components of the beer produced using mixed grains of malt: rice=50:50 (Comparative Example X).

[73] [74] As can be seen in Tables above, the results of analyzing the flavor components of the beers showed that, in Example 1 (Table 1), 34 flavor components were analyzed, whereas in Comparative Example (Table 2), 30 flavor components were analyzed, and in Comparative Example 2 (Table 3), 22 flavor components were analyzed.

[75] Alcohols, including phenyl ethyl alcohol, isoamyl alcohol and isobutyl alcohol, ester compounds, including ethyl acetate, and organic acids, including butanoic acid, which are the characteristic flavor components of beer, were detected in the produced beers, and the contents of most of these components were higher in Example 1 than in Comparative Examples 1 and 2.

[76] Also, lactone compounds, including -hexalactone, -nonalactone and -decalactone, and flavor components, including 1-butanol, 3-methyl-but-3-en-l-ol and 3-methylbutanol, which were not detected in Comparative Example 1, and many compounds and flavor components which were not detected in Comparative Example 2, were detected in Example 1.

[77] The above results revealed that the rice beer produced by the inventive method for producing the rice beer contains increased flavor components, and thus is rich in aroma. Industrial Applicability

[78] According to the inventive method for preparing a rice beer, unhulled rice is added such that saccharifying enzymes can be released from rice bran, thus increasing usable saccharifying enzymes. Thus, the gelatinization and saccharification of starch can be performed at the same time, and the saccharification process can be carried out at a relatively low temperature. Also, because the rice beer of the present invention is produced using unhulled rice as a main raw material, it is richer in nutrients than polished white rice. In addition, the rice beer of the present invention has excellent sensory characteristics, because it combines the inherent flavor of rice bran with the nutty taste of white rice and the flavor of hops and barley.

Claims

[1] A method for producing a rice beer, the method comprising the sequential steps of: immersing mixed grains of unhulled rice and malt in water at a temperature ranging from 48 ⁰C to 53 ⁰C to release saccharifying enzymes; gelatinizing and saccharifying the grains at a temperature ranging from 62 ⁰C to

68 ⁰C; inactivating the saccharifying enzymes and filtering the saccharified material to obtain a wort; adding hops to the wort and boiling the hopped wort; and adding yeast to the wort and fermenting the wort.

[2] The method of Claim 1, wherein water is used in an amount of 500-600 wt% based on the weight of the mixed grains of unhulled rice and malt.

[3] The method of Claim 1, wherein the weight ratio of unhulled rice and malt in the mixed grains is 45-55: 55:45.

[4] The method of Claim 1, wherein the immersion step is carried out for 12-18 minutes.

[5] The gelatinization and saccharification step is carried out for 100-140 minutes.

[6] The method of Claim 1, wherein the sugar content of the wort after the boiling step is 11-12 Brix. [7] The method of Claim 1, wherein the method additionally comprises, after the boiling step, a step of removing a precipitate. [8] The method of Claim 1, wherein the fermentation step comprises the sequential sub-steps of: primarily fermenting the wort at 12 ⁰C to 18 ⁰C for 6 to 8 days to an alcohol content of 3 to 4%; and secondarily fermenting the wort at 0 ⁰C to 2 ⁰C for 2 to 3 weeks to an alcohol content of 4 to 5%. [9] A rice beer produced according to the method of Claim 1.