Production method of glutinous rice lager beer

Abstract

The invention relates to the technical field of beer brewing, in particular to a manufacturing method of glutinous rice lager beer, which comprises the following steps: moderately crushing malt, adding soft water, performing segmented temperature control saccharification to efficiently decompose high-molecular protein, and improving the saccharification efficiency; slowly filtering wort under normal pressure, adding fermented glutinous rice, and washing grains at 78 DEG C, so that the fermented glutinous rice and the wort are deeply fused; boiling the wort and adjusting the pH value; in the boiling process, the sticky rice myrcia is added once and the hops are added twice in sequence, so that the bitter taste and the fragrance are separated and released, the bitter taste support of the wine body is ensured, and the fresh hops fragrance is reserved; cooling the wort, adding the cooled wort into a sealed tank, adding activated yeast, introducing sterile gas, and carrying out pressure-maintaining fermentation for 1-2 weeks; the temperature is reduced by 1-0 DEG C in a gradient manner every day, and the beer is naturally clarified after being stored at low temperature for 3-6 weeks, so that yeast rupture, beer refreshing taste damage and foreign flavor generation are avoided, and slow and stable fusion of alcohol and flavor substances is promoted. The invention solves the problems of single flavor, poor auxiliary material fusion, insufficient clarity and low process standardization in the traditional lager beer process.

Description

Technical Field

[0001] This invention relates to the field of beer brewing technology, and more specifically, to a method for manufacturing a sticky rice lager beer. Background Technology

[0002] Lager beer, as one of the world's most consumed beer categories, is traditionally brewed with low-temperature fermentation and a refreshing taste as its core. However, traditional lagers mostly use malt as the main raw material and rely on yeast to ferment at low temperatures to form the basic flavor. They lack the layered taste brought by special adjuncts and cannot meet consumers' demand for diverse flavors.

[0003] Some existing lager beers attempt to add grains (such as glutinous rice) to their brewing methods. However, due to improper raw material handling (such as poor control of soaking time and cooking temperature) or imbalance of process parameters (such as unstable saccharification temperature and fermentation pressure), the flavors of adjuncts can easily clash with the flavors of malt and hops, resulting in problems such as raw rice taste and astringency.

[0004] In traditional lager brewing, high molecular weight proteins and yeast residues can easily cause the beer to become cloudy after refrigeration. Moreover, most processes use direct 0°C rapid cooling, which can cause yeast to break down and release bitter nucleotides. The post-maturation period is only 2-3 weeks, and the protein-polyphenol complex does not settle completely, requiring the addition of clarifying agents. Although adding clarifying agents can improve clarity, it can also introduce exogenous substances that affect the purity of flavor.

[0005] Therefore, in response to the above problems, the industry urgently needs a lager beer manufacturing method that uses glutinous rice as a flavor carrier, maintains precise low-temperature control throughout the process, and allows for long-term natural clarification. This method aims to solve the problems of single flavor, poor blending of adjuncts, insufficient clarification, and low standardization of the process in traditional lager beer making. Summary of the Invention

[0006] The purpose of this invention is to provide a method for manufacturing glutinous rice lager beer, which solves the problems of monotonous flavor, poor blending of adjuncts, insufficient clarification and low standardization of process in traditional lager beer making.

[0007] The embodiments of the present invention are achieved through the following technical solutions:

[0008] Preferably, a method for manufacturing a sticky rice lager includes the following steps:

[0009] Preferably, in step 1, malt is ground, with the grinding degree controlled to 40-50% fine powder, while coarse powder retains the integrity of the malt husk.

[0010] Preferably, in step 2, the pulverized malt is added to soft water and saccharified in stages with controlled temperature. The saccharification process is as follows: protein rest at 50°C for 20 minutes, saccharification at a low temperature of 65°C for 60 minutes, saccharification at a high temperature of 69°C for 10 minutes, and gelatinization at 78°C for 10 minutes.

[0011] Preferably, step 3 involves slowly filtering the saccharified wort at normal pressure.

[0012] Preferably, in step 4, after filtering the wort, the fermented rice is added and mixed, and the lees are washed, with the washing water temperature controlled at 78℃.

[0013] Preferably, in step 5, the wort from step 4 is boiled and concentrated for 90 minutes, and the pH of the wort is reduced to 5.2-5.4 after boiling.

[0014] Preferably, in step 6, add glutinous rice leaves 30 minutes before the end of boiling, add hops 30-15 minutes before the end of boiling, and add hops a second time 5 minutes before the end of boiling.

[0015] Preferably, in step 7, the wort is cooled to the fermentation temperature, poured into a sealed fermentation tank, activated yeast is added, and sterile gas is introduced to maintain a pressure of 0.1-0.15 MPa for 1-2 weeks.

[0016] Preferably, in step 8, the temperature gradient of the fermented wort is reduced to 0°C, and it is stored at low temperature for 3-6 weeks to allow it to clarify naturally.

[0017] The preferred method for making fermented rice wine in step 4 is as follows:

[0018] S4.1 Soak glutinous rice in water for 5-8 hours, with a glutinous rice to water weight ratio of 1:2.

[0019] S4.2 After soaking, filter out the glutinous rice and steam it for 15-20 minutes.

[0020] S4.3 After the glutinous rice is steamed, add sterile water and cool it to room temperature before adding yeast and stirring.

[0021] S4.4 The stirred glutinous rice is placed in a fermentation tank and fermented for 7 days to separate the fermented rice wine.

[0022] Preferably, the malt in step 1 is light-colored barley malt.

[0023] Preferably, the calcium content in the soft water in step 2 is set within 50-100 ppm, and the sulfate content is <200 ppm.

[0024] Preferably, in step 4, the wort concentration after rinsing is set to 90%-95% of the target beer value.

[0025] Preferably, in step 7, the yeast is activated by cooled boiled water.

[0026] Preferably, the number of active yeast cells in the activated yeast is set in the range of 10×10 cells / mL to 15×10 cells / mL wort.

[0027] Preferably, the starting temperature for wort fermentation in step 7 is set to 12°C.

[0028] Preferably, when the wort fermentation sugar content drops to 3°P, the container is sealed and the temperature is raised to 14°C and maintained for 72 hours.

[0029] Preferably, in step 8, the temperature of the fermented wort is gradually reduced to 0°C at a rate of 1°C per day.

[0030] Preferably, the weight ratio of the added malt, fermented rice, and glutinous rice leaves is set to 250:75:2.

[0031] Preferably, in the wort boiling process of step 6, the ratio of hops added in the two stages is 1:2.

[0032] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0033] 1. The present invention discloses a method for making a glutinous rice lager beer, which uses light-colored barley malt and glutinous rice wine to combine with the herbal aroma of glutinous rice leaves, forming a complex flavor of "refreshing sweetness of malt + mellow rice aroma of glutinous rice + fresh herbal flavor of glutinous rice leaves", which is different from the single malt flavor of traditional lagers. Furthermore, by adding hops in stages (adding bitterness 30-15 minutes before the end of boiling and adding aroma 5 minutes before the end of boiling) and glutinous rice leaves, the bitterness and aroma are released separately, avoiding flavor conflicts and achieving a taste characteristic of "balanced bitterness and aroma, refreshing and not greasy".

[0034] 2. The present invention provides a method for manufacturing a glutinous rice lager beer, which efficiently decomposes high molecular weight proteins through segmented temperature-controlled saccharification, combined with gradient cooling (reducing from 1°C to 0°C per day) and 3-6 weeks of low-temperature storage, to promote the natural sedimentation of yeast and proteins, without the need to add exogenous clarifying agents, thereby making the beer clear and transparent, and less prone to turbidity during storage.

[0035] 3. The present invention provides a method for manufacturing a glutinous rice lager beer. By gradually lowering the temperature, the cell membranes of yeast cells can be prevented from rupturing due to a sudden drop in temperature, thus preventing bitter substances inside the cells from being released into the beer and ruining its refreshing taste. Combined with a long-term low-temperature environment, the metabolic activity of residual yeast can also be inhibited, preventing excessive decomposition of flavor substances and the generation of off-flavors. At the same time, the low temperature also slows down the oxidation reaction of alcohol and other components, making the beer flavor purer. Under long-term low-temperature storage, the molecular movement rate of flavor substances such as alcohol, esters, and higher alcohols slows down. These substances slowly fuse under long-term low temperatures and form a stable balance in a gentle interaction, making the beer flavor more stable, thereby avoiding the decomposition or mutation of flavor substances at high temperatures. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention generally described and shown can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] Example: Brewing 2500L of glutinous rice lager beer

[0039] Ingredient ratio: 500kg malt; 150kg rice wine; 4kg glutinous rice leaves; 1.5kg hops.

[0040] In this embodiment, the steps for manufacturing glutinous rice lager beer are as follows:

[0041] Step 1. Crush 500 kg of malt, controlling the fineness to 40-50% fine powder, while keeping the husks intact for coarse powder.

[0042] The fineness of the malt needs to be kept moderate. If it is ground too finely, the mash produced by malt saccharification will become viscous and difficult to filter; if it is ground too coarsely, the efficiency of malt saccharification and extraction will be reduced.

[0043] In addition, light-colored barley malt is preferred, as it has the characteristics of low color intensity, high enzyme activity, and refreshing flavor.

[0044] Specifically, light-colored barley malt typically has a lower color intensity, resulting in a lighter-colored wort that ultimately gives the sticky rice lager a clear and bright appearance.

[0045] Specifically, light-colored barley malt has a mild malty sweetness, rather than the complex flavors of caramel and nuts found in dark-colored malt. This simple basic flavor can balance the unique aroma of the glutinous rice leaves added in subsequent steps and the mellowness of the brewed beer. This ensures the beer's structural integrity without suppressing the unique flavors brought by the adjuncts, avoiding flavor clashes and highlighting the overall refreshing and harmonious feel.

[0046] Specifically, light-colored barley malt has higher enzyme activity (especially α-amylase and β-amylase), which can efficiently decompose starch into fermentable sugars during the segmented temperature-controlled saccharification process, meeting the metabolic needs of subsequent fermentation yeast in a low-temperature environment and ensuring sufficient and stable fermentation.

[0047] Step 2. Add the crushed malt to soft water and perform saccharification in stages with controlled temperature. The saccharification process is as follows: protein rest at 50℃ for 20 minutes, saccharification at a low temperature of 65℃ for 60 minutes, saccharification at a high temperature of 69℃ for 10 minutes, and gelatinization at 78℃ for 10 minutes.

[0048] The calcium content in the soft water is set between 50-100 ppm, and the sulfate content is less than 200 ppm. This softens the water because hard water (especially with high concentrations of calcium and magnesium ions) can disrupt the osmotic pressure balance of subsequently added yeast cells, slowing down yeast reproduction and reducing the activity of various key enzymes, thus prolonging the fermentation cycle. Furthermore, excessive sulfate content can affect the yeast's metabolic process (in a high sulfate environment, yeast will reduce some sulfate to hydrogen sulfide, producing a rotten egg smell), thereby ruining the beer's refreshing flavor.

[0049] The protein resting process utilizes low temperature (lower heating temperature) to activate proteases (such as endopeptidases and exopeptidases) in malt, thereby breaking down the high molecular weight proteins in the malt raw material into small molecular weight amino acids and polypeptides.

[0050] Preferably, high molecular weight proteins are the main cause of turbidity in beer after refrigeration or prolonged storage. Therefore, their decomposition can significantly improve the clarity of the beer and enhance its transparency. The amino acids produced after decomposition are essential nutrients for yeast reproduction, ensuring stable yeast activity in subsequent fermentation stages.

[0051] During the low-temperature saccharification process, β-amylase activity is highest at this temperature, which can break down starch chains into a large number of small-molecule fermentable sugars (such as glucose and maltose), thereby producing sufficient fermentable sugars to provide substrates for yeast metabolism and ensuring the stable generation of alcohol and CO2 during the main fermentation stage.

[0052] During the high-temperature saccharification process, α-amylase activity dominates at this temperature, which can decompose starch to produce some non-fermentable sugars (such as dextrin). The high-temperature stage can compensate for the starch that is not completely decomposed in the low-temperature stage, ensuring that the starch conversion rate is maximized and the saccharification efficiency is improved.

[0053] During the gelatinization process, high temperature is used to terminate the activity of all amylases and completely gelatinize the starch granules in the mash, reducing the viscosity of the mash. The low viscosity mash is easier to filter in subsequent processes, reducing filtration time and wort loss, and also reducing the risk of turbidity caused by the viscosity of the mash.

[0054] Step 3. Slowly filter the saccharified wort under normal pressure.

[0055] The process involves separating the saccharified wort from the spent grains (malt husks, undigested fiber, etc.) through filtration to ensure that the wort entering subsequent processes is pure and free of impurities. Controlling the flow rate can reduce the amount of spent grain particles suspended in the wort and causing turbidity, thus laying the foundation for the final clear and bright liquor.

[0056] Step 4. After filtering the wort, add 150kg of brewed beer and mix. Wash the lees, keeping the water temperature at 78℃ (not exceeding 78℃). The wort concentration after washing should be controlled at 90%-95% of the target beer value.

[0057] Among them, rinsing the lees with 78℃ hot water can integrate the soluble substances such as sugars and amino acids that have not been fully extracted into the wort, improving the utilization rate of raw materials, and can also prevent the tannins, lignin and other bitter substances in the husks from dissolving due to high temperature (>78℃), thus preventing the wine from producing off-flavors.

[0058] Preferably, adding fermented rice wine before washing the lees allows the glutinous rice fermentation products (such as oligosaccharides and flavor compounds) in the fermented rice wine to be fully extracted by hot water during the washing process and deeply integrated with the wort. Locking the wort concentration at the target value of 90%-95% avoids both excessively high concentrations that lead to fermentation difficulties (high yeast metabolic pressure) and excessively low concentrations that result in a thin-bodied wine.

[0059] The steps for making fermented glutinous rice are as follows:

[0060] S4.1 Soak glutinous rice in water for 5-8 hours (adjust according to room temperature; the lower the room temperature, the longer the soaking time). The weight ratio of glutinous rice to water is 1:2.

[0061] S4.2 After soaking, filter out the glutinous rice and steam it for 15-20 minutes.

[0062] S4.3 After the glutinous rice is steamed, add sterile water so that the glutinous rice can absorb water and achieve the effect of rapid cooling, separation and loosening. When it cools down to room temperature, add the yeast and stir.

[0063] S4.4 The stirred glutinous rice is placed in a fermentation tank and fermented for 7 days to separate the fermented rice wine.

[0064] Step 5. Boil and concentrate the wort from Step 4 for 90 minutes. After boiling, lower the pH of the wort to 5.2-5.4.

[0065] The process involves 90 minutes of continuous boiling to promote the coagulation of proteins in the wort, forming thermal coagulated substances and improving the clarity of the wort. At the same time, some water is evaporated to concentrate the wort, ensuring the fullness of the beer's flavor. The yeast fermentation environment is optimized through subsequent pH adjustment (adding edible acids such as lactic acid to lower the pH value).

[0066] Step 6. Add 4kg of glutinous rice leaves 30 minutes before the end of boiling, add 0.5kg of hops 30-15 minutes before the end of boiling, and add 1kg of hops again 5 minutes before the end of boiling.

[0067] The 30-minute boiling time before turning off the heat allows the volatile aroma compounds (such as terpenes and phenols) in the glutinous rice leaves to fully infuse into the wort, while avoiding the destruction of flavor compounds due to prolonged boiling. This ensures that the unique herbal aroma of the glutinous rice leaves is deeply integrated with the wort and hop flavors, together creating the differentiated flavor of "Glutinous Rice Lager".

[0068] The 30-15 minutes of boiling time before turning off the heat is sufficient to allow the α-acids in the hops to fully isomerize and transform into bitter substances, providing a basic bitterness to the beer, balancing the sweetness of the malt, and preventing a cloying taste.

[0069] Adding hops again 5 minutes before turning off the heat can minimize the volatilization of aroma substances (such as terpenes), highlight the unique woody and fruity aromas of hops, complement the mellow flavor of glutinous rice, and enhance the richness of the aroma layers.

[0070] Preferably, the two additions separate the bitterness from the aroma, ensuring that the beer has enough bitterness to support it (avoiding cloying sweetness) while retaining the fresh hop aroma, which matches the refreshing taste characteristics of the rice lager.

[0071] Step 7. Cool the wort to the fermentation temperature (11℃) to reduce the growth of unwanted bacteria at high temperatures. Pour it into a sealed fermentation tank, add 1kg of activated yeast (dry yeast is activated with cooled boiled water), and introduce sterile gas to promote yeast reproduction. Maintain a pressure of 0.1-0.15MPa and ferment for 1-2 weeks.

[0072] Preferably, rapid cooling can significantly reduce the activity of miscellaneous bacteria, provide a low-temperature fermentation environment, and create a "sterile window" for subsequent yeast inoculation. The cooled sterile air can provide initial oxygen for the yeast, promote its large-scale proliferation during the aerobic respiration stage, and reserve sufficient cell volume for subsequent anaerobic fermentation.

[0073] The activated yeast cell count was set within the range of 10×10⁶ cells / mL to 15×10⁶ cells / mL wort. A higher yeast count allows for rapid fermentation initiation, avoiding excessively long fermentation cycles (which can easily lead to the growth of other microorganisms) due to insufficient yeast. However, an excessively high inoculum size (e.g., exceeding 15×10⁶ cells / mL) can hinder fermentation. 6 A concentration of 100 cells / mL can easily lead to excessive competition for nutrients among yeast, causing some yeast cells to undergo autolysis (cell rupture and release bitter substances).

[0074] The initial fermentation temperature of the wort was set at 12°C. When the sugar content of the wort dropped to 3°P, the container was sealed and the temperature was raised to 14°C to start diacetyl reduction, which was maintained for 72 hours. The total fermentation time was 1-2 weeks, and the fermentation process ended when the sugar content of the wort reached 3-5°P.

[0075] Preferably, an initial temperature of 12°C can reduce yeast ester production (such as ethyl acetate) and prevent off-flavors such as banana flavor from ruining the refreshing taste of beer; 14°C diacetyl reduction can decompose raw grassy substances into off-flavor components and inhibit the generation of off-flavors; while a pressure of 0.1-0.15MPa can retain an appropriate amount of CO2, giving the beer a moderate carbonation and forming a balance with the mild flavor of glutinous rice.

[0076] Step 8. Gradually reduce the temperature of the fermented wort to 0°C at a rate of 1°C per day, and store it at low temperature for 3-6 weeks to allow it to clarify naturally.

[0077] Gradual, slow cooling prevents yeast cells from rupturing due to sudden temperature drops (such as directly from 14°C to 0°C), thus preventing the release of bitter substances (such as nucleotides) into the beer and ruining its refreshing taste. Combined with a prolonged low-temperature environment, it also inhibits the metabolic activity of residual yeast, preventing excessive decomposition of flavor substances and the generation of off-flavors. At the same time, low temperatures slow down the oxidation reaction of alcohol and other components, making the beer's flavor purer. Under long-term low-temperature storage, the molecular movement rate of flavor substances such as alcohol, esters, and higher alcohols slows down. These substances slowly fuse under long-term low temperatures and form a stable equilibrium through gentle interaction, making the beer's flavor more stable (therefore, the longer the storage time, the purer the beer flavor), thereby avoiding the decomposition or mutation of flavor substances at high temperatures.

[0078] This method, employing a low-temperature, long-duration natural clarification process, allows yeast cells to gradually aggregate into larger particles as their metabolism ceases, slowly settling to the bottom of the tank as the temperature decreases. Simultaneously, incompletely decomposed high-molecular-weight proteins in the wort denature and precipitate under prolonged low temperatures, forming stable sediments, thus achieving natural sedimentation of yeast and proteins. This combination of "low temperature + long duration" enhances the clarity of the spirit more effectively than low-temperature treatment alone, reducing the turbidity issues caused by incomplete sedimentation in traditional rapid fermentation. Furthermore, natural clarification avoids the off-flavors that may be introduced by adding chemical clarifying agents (such as silica gel), preserving the original flavors of glutinous rice, malt, and hops to the greatest extent possible, highlighting the pure taste of the product.

[0079] Furthermore, in order to ensure the stability of the brewing process and maintain the stability of its flavor, fixed sources of raw materials are selected for all brewing ingredients.

[0080] The sources of each brewing ingredient in real life are shown in the table below:

[0081] Raw material categories Source of raw materials Light-colored barley malt Pilsner malt, Australian malt, Canadian malt Fermented Rice Northeast Wuchang Edelweiss Glutinous Rice Glutinous rice leaves Yunnan glutinous rice leaves Hops Czech Saaz yeast Furmandis S23 dry yeast

[0082] Pilsner malt, as a classic light malt, has stable enzyme activity and high saccharification efficiency, making it a traditional choice for lager beer and laying a pure foundation for its flavor. Malts such as Australian malt and Canadian malt have moderate protein content, resulting in a more rounded beer after fermentation, which complements the richness of glutinous rice.

[0083] The best quality rice used is Wuchang Edelweiss glutinous rice from Northeast China. Its grains are plump, high in starch, and have a high proportion of amylopectin, resulting in a unique glutinous rice aroma and a slightly mellow, rich rice flavor after fermentation. Soaking for 5-6 hours in summer and 8 hours in winter, followed by steaming and fermentation for 7 days, helps maintain the pure flavor of the rice wine, eliminating any raw rice or rancid taste.

[0084] The best quality is Yunnan glutinous rice leaves, which have a fresh herbal aroma and a slight woody note. Adding a small amount can highlight the characteristics without being too overpowering.

[0085] The preferred choice is Czech Saaz, a classic European aromatic hop, characterized by its mellow woody and citrus aromas, low bitterness, and delicate flavor, which is suitable for the "refreshing and non-bitter" requirements of lager beer.

[0086] Preferably, Fermandis S23 yeast is a bottom-fermenting yeast that is resistant to low temperatures, has low ester production, and relatively stable activity. Its inoculation amount is highly compatible with the low-temperature fermentation environment of glutinous rice lager.

[0087] Experimental Example 1

[0088] In this embodiment, in order to improve the degree of saccharification of malt and maintain the clarity of wort after saccharification, segmented temperature-controlled saccharification was adopted. Please refer to Tables 1, 2, 3 and 4. In order to determine whether different saccharification stages have an impact on malt saccharification, multiple control groups with different saccharification processes were set up for comparative experiments.

[0089] The configuration conditions for Experiment 1 are as follows:

[0090] Malt was ground and soft water was added. The experimental group consisted of protein rest + low-temperature saccharification + high-temperature saccharification + gelatinization by heating, while the control group consisted of low-temperature saccharification + high-temperature saccharification + gelatinization by heating. The experiment of each group was repeated 4 times for different saccharification stages, and the detection time was based on the 4 parallel measurements.

[0091] Table 1: Segmented Temperature-Controlled Saccharification

[0092]

[0093]

[0094] As shown in Table 1, the control group without protein rest was unable to break down the proteases in the malt into amino acids because the proteases in the malt were not activated by the low temperature. This resulted in excessive residues and made the wort more turbid after saccharification. This indicates that high molecular weight proteins affect the clarity of the wort after saccharification, and a protein rest stage is needed to improve the decomposition rate of high molecular weight proteins in the malt.

[0095] The configuration conditions for Experiment 2 are as follows:

[0096] Malt was ground and soft water was added. The experimental group consisted of protein rest + low-temperature saccharification + high-temperature saccharification + gelatinization by heating, while the control group consisted of protein rest + high-temperature saccharification + gelatinization by heating. The experiment of each group was repeated 4 times for different saccharification stages, and the detection time was based on the 4 parallel measurements.

[0097] Table 2: Segmented Temperature-Controlled Saccharification

[0098] experimental group Control group 1 Control group 2 Control group 3 Fermentable sugar content 7.0°P 6.4°P 6.2°P 6.4°P

[0099] As shown in Table 2, the control group without a low-temperature saccharification stage had consistently low α-amylase activity, resulting in decreased starch decomposition efficiency and difficulty in generating small-molecule fermentable sugars. This led to a decrease in the amount of fermentable sugars and consequently affected yeast reproduction. Therefore, a low-temperature saccharification stage is needed to improve the decomposition rate of starch into small-molecule fermentable sugars.

[0100] The configuration conditions for Experiment 3 are as follows:

[0101] Malt was ground and soft water was added. The experimental group consisted of protein rest + low-temperature saccharification + high-temperature saccharification + gelatinization at elevated temperature, while the control group consisted of protein rest + low-temperature saccharification + gelatinization at elevated temperature. The experiment of each group at different saccharification stages was repeated 4 times, and the detection time was based on the 4 parallel measurements.

[0102] Table 3: Segmented Temperature-Controlled Saccharification

[0103] experimental group Control group 1 Control group 2 Control group 3 Starch conversion rate 97.1％ 90.3％ 90.8％ 89.4％

[0104] As shown in Table 3, the control group without a high-temperature saccharification stage had consistently low β-amylase activity, resulting in decreased efficiency in the further decomposition of starch. This made it difficult to completely decompose the starch that was not fully decomposed in the low-temperature stage, leading to a decrease in starch conversion rate. Therefore, a high-temperature saccharification stage is needed to promote the complete decomposition of starch.

[0105] The configuration conditions for Experiment 4 are as follows:

[0106] Malt was ground and soft water was added. The experimental group consisted of protein rest + low-temperature saccharification + high-temperature saccharification + gelatinization. The control group consisted of protein rest + low-temperature saccharification + high-temperature saccharification. The experiment of each group was repeated 4 times for different saccharification stages. The detection time was based on the 4 parallel measurements.

[0107] Table 4: Segmented Temperature Controlled Saccharification

[0108] experimental group Control group 1 Control group 2 Control group 3 mash viscosity 15cP 21cP 22cP 19cP wort turbidity 5NTU 13NTU 14NTU 13NTU

[0109] As shown in Table 1, in the control group without temperature gelatinization, various enzymes were deactivated by high temperature. As a result, some enzymes in the wort continued to work (such as proteases), causing large molecules such as high-molecular-weight proteins from the malt raw materials to remain in the wort. This made the wort more turbid after saccharification, which affected the clarity of the wort after saccharification. Therefore, a temperature gelatinization stage is needed to improve the clarity of the malt raw materials and deactivate various enzymes.

[0110] Experimental Example 2

[0111] In this embodiment, in order to ensure that the beer has sufficient bitterness to support it (avoiding sweetness) while retaining a fresh hop aroma, which is in line with the refreshing taste characteristics of glutinous rice lager beer, hops were added twice at different times. In order to determine whether the addition time and number of additions have an impact on the flavor of the beer, multiple control groups with different addition times were set up for comparative experiments.

[0112] The experimental setup conditions are as follows:

[0113] Boil the wort, add a measured amount of glutinous rice leaves 30 minutes before the end of boiling, and add a measured amount of hops once before the end of boiling. Each experiment with different hop addition times was repeated 4 times, and the time consumption was measured based on the 4 parallel measurements.

[0114] Table 5: Time for adding hops at a single time during wort boiling

[0115]

[0116] As shown in Table 5, during the wort boiling process, the earlier the hops are added before the end of boiling, the longer the hop cooking time, the higher the α-acid isomerization rate in the hops, the more bitter substances are converted, and the stronger the bitterness. Conversely, the later the hops are added before the end of boiling, the shorter the hop cooking time, the lower the volatility of aroma substances in the hops, the higher the content of aroma substances, and the more fragrant the hop aroma. (Note that hops need to be cooked to infuse aroma substances into the wort; therefore, adding hops 5 minutes before the end of boiling will produce more aroma substances.)

[0117] Therefore, in order to achieve the bitterness support and retain the hop aroma of this glutinous rice lager, hops need to be added in two stages: the first addition of hops increases the bitterness of the beer, and the second addition of hops increases the aroma of the beer.

[0118] Experiment Example 3

[0119] In this embodiment, in order to ensure that the flavor molecules of the wine are integrated during the fermentation and storage process, and to allow the wine to clarify naturally and maintain its flavor without using chemical clarifying agents that may affect the flavor of the wine, a long-term gradient slow cooling fermentation and storage method was adopted. In order to determine whether the gradient cooling has any effect on the flavor and clarity of the wine, multiple control groups with different cooling rates and storage times were set up for comparative experiments.

[0120] The configuration conditions for experimental group a are as follows:

[0121] After fermenting the wort with yeast for 1-2 weeks, the temperature was gradually reduced. Each experiment with different storage times was repeated 4 times, and the time consumption was measured based on the 4 parallel measurements.

[0122] Table 6: Wort Fermentation and Storage Time

[0123]

[0124] As shown in Table 6, during the cooling and storage of wort, the turbidity of the beer gradually decreased with the increase of storage days, and the TBA value (thiobarbituric acid value) of the beer also gradually decreased. The rate of decrease in turbidity followed a power function curve (the exponent of the power function was negative). After 15 days of storage, the rate of decrease in turbidity began to decrease significantly, and by 40 days, the turbidity of the beer gradually stabilized at around 2 NTU. Therefore, the optimal storage time for this glutinous rice lager beer should be 2 to 6 weeks.

[0125] Among them, the TBA value of beer is a key indicator for measuring the aging degree and flavor stability of beer. A gradual decrease in the TBA value indicates that the flavor substances in the beer begin to blend and form a balance, and the oxidation and decomposition of the flavor substances gradually decreases, making the beer flavor gradually more stable. When the TBA value of beer is below 0.4 mg / kg, the oxidative taste of beer is no longer obvious, and the flavor begins to stabilize.

[0126] The configuration conditions for experimental group b are as follows:

[0127] After fermenting the wort with yeast for 1-2 weeks, it was stored for 2-6 weeks. The initial storage temperature was 14℃, and the minimum storage temperature was 0℃. Each group of experiments with different gradient cooling rates was repeated 4 times, and the detection time was based on the 4 parallel measurements.

[0128] Table 7: Wort Fermentation and Storage Time

[0129]

[0130] As shown in Table 7, during the wort cooling and storage process, the more drastic the temperature change experienced by the yeast in the liquor increases with the increase in the cooling range, the higher the yeast breakage rate becomes, resulting in off-flavors, bitterness, and an increased bitterness value. Therefore, the lower the cooling range, the lower the yeast breakage rate in the liquor. Thus, by gradually lowering the temperature by 1°C per day, the flavor of the liquor can be maintained and the generation of off-flavors can be reduced.

[0131] It is worth noting that, as shown in Table 6, the entire fermentation and storage cycle of the glutinous rice lager beer is controlled within 2 to 6 weeks. Therefore, by lowering the temperature by 1°C per day, the initial fermentation temperature can be brought to 0°C before the two-week storage cycle, thus maintaining low-temperature storage conditions.

[0132] It is worth noting that in Table 7, when the temperature drop is 0 (i.e., it is maintained at 14℃), the wine will actually become bitter after fermentation and storage. This is because the fermentation and storage temperature is relatively high. Under high temperature, the yeast metabolism rate will increase, which will produce off-flavors. Moreover, various flavor substances will be more likely to undergo oxidation reactions due to high temperature, thereby increasing the TBA value and turbidity of the wine, and thus producing off-flavors and bitterness, affecting the flavor of the wine.

[0133] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for manufacturing glutinous rice lager beer, characterized in that, Includes the following steps: Step 1. Grind the malt, controlling the grinding degree to 40-50% fine powder, while retaining the integrity of the malt husk in the coarse powder; Step 2. Add the crushed malt to soft water and saccharify in stages with controlled temperature. The saccharification process is as follows: protein rest at 50℃ for 20 minutes, saccharification at a low temperature of 65℃ for 60 minutes, saccharification at a high temperature of 69℃ for 10 minutes, and gelatinization at 78℃ for 10 minutes. Step 3. Slowly filter the saccharified wort under normal pressure; Step 4. After filtering the wort, add the fermented rice and mix. Wash the lees, keeping the water temperature at 78℃. Step 5. Boil and concentrate the wort from Step 4 for 90 minutes. After boiling, lower the pH of the wort to 5.2-5.

4. Step 6. Add glutinous rice and bay leaves 30 minutes before the end of boiling, add hops 30-15 minutes before the end of boiling, and add hops a second time 5 minutes before the end of boiling. Step 7. Cool the wort to the fermentation temperature, pour it into a sealed fermentation tank, add activated yeast, and purge with sterile gas, maintaining a pressure of 0.1-0.15 MPa, and ferment for 1-2 weeks; Step 8. Reduce the temperature gradient of the fermented wort to 0°C and store it at low temperature for 3-6 weeks until it clarifies naturally.

2. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, Including the method for making fermented rice wine in step 4, the steps are as follows: S4.1 Soak glutinous rice in water for 5-8 hours, with a weight ratio of glutinous rice to water of 1:2; S4.2 After soaking, filter out the glutinous rice and steam it for 15-20 minutes. S4.3 After the glutinous rice is steamed, add sterile water and cool it to room temperature before adding yeast and stirring. S4.4 The stirred glutinous rice is placed in a fermentation tank and fermented for 7 days to separate the fermented rice wine.

3. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, The malt used in step 1 is light-colored barley malt.

4. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, In step 2, the calcium content in the soft water is set between 50-100 ppm, and the sulfate content is <200 ppm.

5. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, In step 4, the wort concentration after rinsing is set to 90%-95% of the target beer value.

6. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, In step 7, the yeast is activated by cooled boiled water; The number of active yeast cells in the activated yeast is set within the range of 10×10 cells / mL to 15×10 cells / mL wort.

7. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, In step 7, the initial temperature for wort fermentation is set to 12°C. When the wort fermentation sugar content drops to 3°P, seal the container and raise the temperature to 14°C, maintaining this temperature for 72 hours.

8. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, In step 8, the temperature of the fermented wort is gradually reduced to 0°C at a rate of 1°C per day.

9. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, The weight ratio of malt, rice wine, and glutinous rice leaves added is set to 250:75:

2.

10. The method for manufacturing a glutinous rice lager beer according to claim 1, characterized in that, In step 6, during the wort boiling process, the ratio of hops added in the two stages is 1:2.

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