Preparation method of green tea beer

Abstract

The invention discloses a preparation method of green tea beer, which comprises the following steps: crushing malt, putting the crushed malt into a saccharifying pot, adding pure water and inorganic salt, and heating to carry out protein enzymolysis; after saccharification is completed, a clarifying agent is added for adsorption; boiling the saccharified liquid, adding humulus lupulus and a part of tea leaves after boiling, and filtering and separating to obtain fermented wort; two-stage cooling is adopted, the fermented wort is rapidly cooled to the fermentation temperature, and then the fermented wort is added into a fermentation tank to be cooled and precipitated; after discharging the cold flocculate, inoculating beer yeast into the fermentation tank, after fermentation is completed, adding the residual tea leaves, soaking for a plurality of days, then cooling, carrying out cold precipitation, discharging residues, and curing to obtain the green tea beer. According to the invention, malt polyphenol and a large amount of protein are removed by enzymolysis of protein through protease and adsorption by using an adsorption material before the tea is added, so that the concentration of protein polyphenol flocculate formed by beer is reduced, and the clarity and taste of the beer are improved.

Description

Technical Field

[0001] The invention relates to the technical field of alcoholic beverage preparation methods, and in particular to a preparation method of green tea beer. Background Art

[0002] Beer, one of the three major alcoholic beverages in the world, originated in Egypt and developed in Europe. Adding ingredients with local flavors to beer has always been a common practice in beer brewing, and is an important part of beer culture. Before the discovery of hops, European beer generally added "spice bags" that were monopolized by the royal family. In modern beer, bitter orange peel and coriander seeds are added to wheat beer in the Hoegaarden region of Belgium; ginger, lemongrass, and dandelions are added to saison beer in the Wallonia region; sea salt and rock salt are added to gose beer in the Goslar region of Germany, etc.

[0003] Green tea is a tea drink with Chinese characteristics. Green tea is unfermented tea. Due to its characteristics, it retains more natural substances in fresh leaves. Among them, tea polyphenols and caffeine retain more than 85% of fresh leaves, chlorophyll retains about 50%, and vitamin loss is also less, thus forming the characteristics of green tea "clear soup, green leaves, strong astringent taste". It has special effects on anti-aging, anti-cancer, anti-cancer, sterilization, anti-inflammatory, etc., which are beyond the reach of fermented tea.

[0004] Document 1: Analysis of the Flavor Characteristics of Autumn Floral-scented Green and Black Teas of 'Qiancha No. 1'

[0005] Document 1 discloses that the content of tea polyphenols such as catechins in green tea is higher than that in black tea. Tea polyphenols are the main flavoring substances that cause bitterness, and the content of tea polyphenols is positively correlated with the bitterness of tea leaves. Different amino acids in green tea also present different flavors. Among the aroma components of green tea, n-decanol has the largest OAV value.

[0006] There are already many literature reports in the prior art that use different tea leaves to prepare tea beer. The tea beer process in the prior art is summarized as follows.

[0007] Document 2: CN 112708517B "A dark tea beer and its preparation method"

[0008] Document 2 discloses: a method for preparing black tea beer, comprising the steps of: saccharification: mixing barley malt with water, saccharification by stepwise heating, and filtering once to obtain wort; boiling: boiling the wort, adding hops and black tea, adjusting the pH value, and then filtering twice; batch cooling and oxygenation: taking 60%-70% of the wort to cool and oxygenate, and loading it into fermentation tank No. 1, taking 30%-40% of the wort to cool and oxygenate, and loading it into fermentation tank No. 2; one batch fermentation: inoculating brewer's yeast in fermentation tank No. 1, inoculating crown-like cysts in fermentation tank No. 2, adding white sugar and black tea, and fermenting once in fermentation tank No. 1 and fermentation tank No. 2 respectively; secondary mixed fermentation: adding the fermented wort in fermentation tank No. 2 to fermentation tank No. 1 and mixing for fermentation. The preparation of black tea beer by this method reduces the risk of introducing additives when adding tea concentrate, greatly improves the tea aroma and fungus flower aroma, and improves the antioxidant property of the wine.

[0009] Document 3: CN114736750A "Preparation process of jasmine tea craft beer"

[0010] Document 3 discloses a process for preparing jasmine tea craft beer, which is characterized by comprising the following steps:

[0011] 1) Preparation of malt mash: malt is crushed and mixed with water to obtain malt mash;

[0012] 2) Saccharification and filtration: Saccharify the mash obtained in step 1) by heating it in stages, and filter it once to obtain saccharified wort for later use;

[0013] 3) Preparation of jasmine tea powder: extracting jasmine tea at low temperature, centrifuging the extract at high speed to obtain jasmine tea extract, hydrolyzing the jasmine tea extract with enzymes to obtain enzymatic hydrolysate, and concentrating the enzymatic hydrolysate with reverse osmosis membranes and freeze-drying to obtain jasmine tea powder;

[0014] 4) boiling: boiling the saccharified wort obtained in step 2) for 110 minutes, adding hops and jasmine tea powder respectively during the boiling process to obtain hot wort containing jasmine tea powder and hops;

[0015] 5) Cooling: Cooling the hot wort in step 4) by rotary sedimentation to obtain cold wort;

[0016] 6) Fermentation: oxygenate the cold wort, add yeast and use the "one-can method" to carry out primary fermentation at low temperature for 5-10 days, remove the yeast, carry out secondary fermentation and natural sedimentation to obtain the finished product of jasmine tea powder craft beer.

[0017] Both Reference 2 and Reference 3 are common methods for preparing tea beer, which use different types of tea and undergo basic processing steps such as malt crushing, saccharification, tea component extraction, hot wort fermentation, and post-fermentation filtration. The methods used in Reference 2 and Reference 3 will have the problem of high overall turbidity of the beer.

[0018] Reference 4: Study on the Complexation Characteristics of Tea Polyphenols and Their Oxidation Products with Protein

[0019] Document 4 discloses that tea polyphenols are secondary metabolites of tea trees and are natural organic products, accounting for a considerable proportion of about 20% to 30% in tea leaves. Among polyphenols in tea leaves, flavanol compounds (mainly catechins) are the most important, accounting for about 60% to 80% of the total polyphenols. They are the main substances of the astringency of tea soup. The ester-type catechins, which account for about 80% of catechins, have a strong bitter taste and strong astringency, and are the main component of astringency. In addition, in the processing of tea beverages, instant tea, etc., there is a cold mixing phenomenon. This phenomenon is mainly caused by the interaction between tea polyphenols and proteins, which are complexed into complexes with larger molecular weight. The precipitation of polyphenols on proteins can be considered as a surface phenomenon. It can be divided into two steps. First, polyphenols bind to the protein surface, and then form multi-point cross-linking between protein molecules, which eventually leads to precipitation. The main binding mode between polyphenols and proteins is that polyphenols are bonded to the peptide groups of protein molecules with double-point hydrogen bonds with their adjacent phenolic hydroxyl groups.

[0020] It can be seen from Document 4 that the main reason for the turbidity of Documents 2 and 3 and other tea beers in the prior art is that the hydrogen bonds formed between the protein in the beer and water are broken, and the protein is complexed or combined with polyphenols to form small particles that precipitate, forming floccules at low concentrations or precipitates at high concentrations; and long-term exposure to oxygen will also lead to permanent turbidity, affecting the non-biological stability of the beer.

[0021] In order to solve the problem of beer turbidity, in the prior art, a clarifier is often added after tea leaves are added for adsorption. Tea leaves are generally added after the saccharification stage. Therefore, in the prior art, a clarifier is generally added after saccharification or during the fermentation stage.

[0022] Document 5: CN1528872A "Golden Wheat Tea Beer and Its Preparation Method"

[0023] Document 5 discloses: Golden Barley Tea Beer and its preparation method, including filling the filter with water, removing the air, and then stirring diatomaceous earth and water in a soil mixing tank at a ratio of 1:10, first putting in coarse soil, and then putting in fine soil, and pre-coating at a ratio of coarse soil: fine soil = 1:1; after normal wine filtering begins, adding barley essence to the adding tank and evenly entering the clear beer tank with the wine, adding silica gel and sodium bisulfite to the soil mixing tank and stirring evenly.

[0024] Document 6: CN114774222A "A method for preparing Tibetan tea beer"

[0025] Document 6 discloses: a method for preparing Tibetan tea beer, the preparation process includes adding hops and tea powder to the saccharification liquid and boiling it, adding carrageenan and continuing to boil it; then cooling and filtering it for fermentation; adding beer silica gel and PVPP clarifiers in the late fermentation stage for mixing, and then filtering to remove the precipitate to obtain the beer stock solution. In the preparation process, adding carrageenan, beer silica gel and PVPP for clarification treatment can remove tea particles and suspended impurities in the saccharification liquid and improve the clarity of the beer.

[0026] Document 7: CN 111748427 A "Green tea beer and brewing method thereof"

[0027] Document 7 discloses: The brewing method of green tea beer includes: (1) making Tongcheng green tea powder; (2) preparing beer saccharification liquid as follows: saccharifying malt, filtering to remove lees, and vortexing to remove heat coagulation to obtain saccharification liquid; (3) adding green tea powder and hops in a certain proportion: a. adding green tea powder and hops to the saccharification liquid in a mass ratio, boiling, and then loading into a sterile fermentation device after high-temperature instant sterilization, and removing cold coagulation after cooling; b. fermentation and post-treatment: adding brewer's yeast to the fermentation device of step (3.a), controlling the temperature after uniform distribution, and performing pre-fermentation. When the diacetyl content decreases, the pre-fermentation is terminated and the yeast mud is removed; then adjusting the temperature, performing post-fermentation, and then removing the precipitate to obtain the original wine, and then adding cross-linked polyvinyl pyrrolidone to the original wine to remove anthocyanins, and obtaining green tea beer after membrane filtration and sterilization.

[0028] Reference 8: Comparison of nutritional components and phenolic content of wheat bran from different sources

[0029] Document 5 discloses the use of silica gel to filter beer, and Document 6 discloses the use of carrageenan, beer silica gel and PVPP for clarification treatment; Document 7 discloses the use of cross-linked polyvinyl pyrrolidone to remove anthocyanins, and a method of obtaining green tea beer after membrane filtration and sterilization. It can be known from the prior art that beer can be filtered or adsorbed in a variety of ways in the beer process to remove impurities, but the principles of different purification methods or materials are different. For example, cross-linked polyvinyl pyrrolidone PVPP has a positive charge and can adsorb polyphenols and alkaloids with negative charges, and can form complexes with phenols and alkaloids, thereby removing polyphenols in beer. Silica gel can adsorb yeast and polyphenols, and PVPP has a weak ability to adsorb and remove yeast, but its ability to adsorb polyphenols is stronger than that of silica gel. The form of impurity removal of silica gel and PVPP is adsorption, and the role of the sterile membrane is more to filter yeast cells and large particle impurities in beer, and filtering out yeast-free impurities can increase the biological stability of beer. Therefore, due to the characteristics of different purification materials, appropriate purification and clarification methods and materials are often selected according to needs during the beer production process.

[0030] Document 8 discloses that the average contents of the three main nutrients of bran, namely total dietary fiber, protein and total starch, are 47.30%, 19.85% and 16.90% respectively. Of the total phenol content, 73.9-79.1% are bound phenolic acids; dietary fiber and alkaline bound phenolic acid (BBPA) are extremely significantly negatively correlated with total starch, pentosan and BBPA are extremely significantly positively correlated with dietary fiber, pentosan is extremely significantly positively correlated with BBPA, and acid bound phenolic acid (ABPA) is extremely significantly positively correlated with total phenol. It can be seen from Document 8 that bran, as one of the components of malt, contains a large amount of protein and polyphenols. Secondly, malt itself also contains a certain amount of bran polyphenols.

[0031] The main raw material of beer is malt, which contains phenolic substances and proteins. Therefore, the protein in beer mainly comes from malt, but the protein in malt is also one of the important factors in maintaining the foam characteristics of beer. In document 6, carrageenan is added for adsorption after saccharification and boiling, and then filtered through a plate and frame. After fermentation, a clarifier is added at low temperature for adsorption to remove phenolic substances and protein complexes and other impurities; in document 7, after saccharification, cyclotron precipitation is used to remove hot coagulants, tea powder is added for boiling, and then cooled to discharge cold coagulants, PVPP is added at low temperature for impurity removal after fermentation, and then membrane filtration is performed to obtain green tea beer.

[0032] From the perspective of material properties, whether it is silica gel or PVPP, its adsorption performance cannot distinguish the source of phenolic substances. During the adsorption process, it will adsorb tea polyphenols, bran polyphenols in malt, and hop polyphenols. References 6 and 7 use adsorption materials for adsorption after tea powder is added to remove polyphenols and retain other characteristic substances of tea. Since the adsorption is performed after the tea is added, the adsorption material will also adsorb a large amount of tea polyphenols and tea aroma substances during adsorption; this greatly reduces the tea flavor of the tea beer actually obtained.

[0033] In fact, the inventors have found that during the crushing, heating and saccharification process of malt, the polyphenols bran polyphenols and proteins of the malt itself are released, so that even when tea leaves are not added, polyphenols and proteins are naturally present in the wort or saccharified liquid, and the content of protein is much higher than that of bran polyphenols. At the same time, due to the high temperature during saccharification and boiling, the complex hydrogen bonds between protein and polyphenols will break at high temperatures, and the protein and polyphenols will not be complexed under high temperature conditions, so flocculation and turbidity will not occur. When cooled after fermentation, polyphenols will be complexed with proteins to form turbid floccules under low temperatures. Therefore, in the prior art, adsorbent materials are used for purification after adding tea leaves. Since it is a high temperature condition at this time, polyphenols are mainly removed during the purification process. Since the protein-polyphenol complex is not generated, it is not actually eliminated.

[0034] Furthermore, tea leaves are rich in tea polyphenols, which, together with wheat bran polyphenols and hop polyphenols, are easily added to the wort in excess, causing the beer to have an astringent taste. Some processes choose to reduce the amount of tea added to the hot end, or directly add tea extracts to the finished beer, which can reduce the astringency, but it leads to nutrient loss and a single taste.

[0035] In summary, the preparation process of tea beer in the prior art has the following defects:

[0036] 1. The raw materials contain a variety of polyphenols, including tea polyphenols, bran polyphenols and hop polyphenols. If adsorption materials are not used for adsorption, excessive polyphenols are likely to produce a strong bitter taste, and after fermentation, polyphenols can form floccules with proteins at low temperatures, resulting in poor clarity. In order to improve clarity, the prior art chooses to remove polyphenols before fermentation, so that there is no polyphenol complex with protein after fermentation and cooling, thereby eliminating floccules. Therefore, adsorption materials are used for treatment after adding tea leaves; or adsorption materials are used to directly adsorb floccules after fermentation to improve clarity. During adsorption, due to the presence of tea polyphenols, bran polyphenols and hop polyphenols, the adsorption process cannot be controlled. Not only various polyphenols are adsorbed, but also some tea aroma substances are adsorbed, resulting in the final tea beer having an unclear tea flavor.

[0037] 2. Document 7 sterilizes the mixture at high temperature after boiling, and then puts it into a fermentation device, and discharges the condensate after cooling. Before the condensate is discharged, a cyclotron precipitation has been performed to remove the heat coagulation, so most of the condensate is thermosoluble substances, which have a large solubility at high temperature and a significantly reduced solubility at low temperature, including proteins. Proteins will form condensates after cooling, but Document 7 does not explain the relationship between cooling efficiency and protein cold precipitation effect. Summary of the invention

[0038] The purpose of the present invention is to provide a method for preparing green tea beer, which can retain tea polyphenols and other flavor characteristic substances of the tea leaves themselves, remove other polyphenol substances, reduce the bitter taste, and improve the clarity of beer at low temperatures.

[0039] Another technical problem solved by the present invention is: in the cooling process after saccharification and before fermentation, more protein cold floccules are allowed to precipitate, thereby reducing the protein content and protein precipitation in beer.

[0040] A secondary technical problem that the present invention needs to solve is: how to improve and increase the flavor level of beer.

[0041] To achieve the above object, the present invention provides a method for preparing green tea beer, comprising the following steps:

[0042] Step (1) Prepare the raw materials by weight:

[0043] 400 parts of malt, 2 to 3 parts of hops, 1 to 2 parts of brewer's yeast;

[0044] 3 to 6 parts of tea leaves; 1 to 2 parts of lactic acid; 2 to 5 parts of clarifier;

[0045] 1 to 2 parts of inorganic salt; 2500 to 3000 parts of pure water;

[0046] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1-2:5-6;

[0047] Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salts, adding lactic acid to adjust the pH value, crushing the malt and putting it into the saccharification pot, adding protease and maintaining the temperature at 50°C to 55°C for protein enzymolysis; then heating it up for saccharification until saccharification is completed; after saccharification is completed, adding a clarifier for adsorption to obtain a saccharified liquid;

[0048] Step (3) boiling the saccharified liquid, adding hops and a portion of tea leaves after boiling; filtering to separate the impurities including tea leaves, hops, and heat-dissociated protein from the saccharified liquid to obtain fermented wort;

[0049] Step (4) adopts two-stage cooling to quickly cool the fermented wort to a fermentation temperature of 18°C ​​to 22°C within 30min to 45min, then add the fermented wort to a fermentation tank for cooling and precipitation, and discharge the cold flocculants;

[0050] After the cold flocculants are discharged in step (5), brewer's yeast is inoculated in the fermentation tank. After the fermentation is completed, the remaining tea leaves are added and soaked for several days, and then the temperature is lowered to cool and settle to discharge the residue; and then the green tea beer is obtained by ripening.

[0051] Preferably, the raw materials prepared in step (1) include, by weight:

[0052] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0053] 4 parts of tea leaves; 1 part of lactic acid; 4 parts of clarifier;

[0054] 1.5 parts of inorganic salt; 2700 parts of pure water;

[0055] Among them, the inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each portion of inorganic salt is 5:1:5.5.

[0056] Preferably, the clarifier in step (1) is beer silica gel, PVPP or a mixed clarifier of beer silica gel and PVPP mixed in any proportion.

[0057] Preferably, the specific operation process in step (2) of the present invention is:

[0058] Put pure water into a saccharification pot, heat it to 50℃~55℃, add inorganic salt, add lactic acid to adjust the pH to 5.3~5.5, crush the malt and put it into the saccharification pot, add protease and keep it at 50℃~55℃ for 10min~20min for protein enzymolysis; then heat it to 60℃~65℃ and keep it for 40min~60min, then heat it to 65℃~70℃ and keep it for 10min~20min for saccharification, then heat it to 75℃~78℃ and keep it for 10min~15min to complete saccharification; then add a clarifier for adsorption to obtain a saccharified liquid.

[0059] Preferably, the specific operation process in step (3) of the present invention is:

[0060] The saccharification liquid is boiled and kept for 60 minutes; hops are divided into three parts, and one part of hops is added at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then 1 to 2 parts of tea leaves are added at 50 minutes after boiling; then cyclotron sedimentation method is used for filtering to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharification liquid to obtain fermented wort.

[0061] Preferably, in step (4), the cold flocculants in the fermentation tank are discharged after cooling and settling for 8 to 10 hours.

[0062] Preferably, in step (5), the mixture is first fermented at 18°C ​​to 20°C, the substrate concentration is detected during the fermentation process, and when the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 to 7 days, then the temperature is lowered to 17°C and the remaining tea leaves are added and soaked for 3 to 5 days; after the soaking is completed, the temperature is lowered to 2°C, the residue is removed after cooling and precipitation, and then the mixture is matured at 8°C for 15 to 20 days to obtain green tea beer.

[0063] A specific embodiment of the present invention discloses a method for preparing green tea beer, comprising the following steps:

[0064] Step (1) Prepare the raw materials by weight:

[0065] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0066] 4 parts of tea leaves; 1 part of lactic acid; 4 parts of clarifier;

[0067] 1.5 parts of inorganic salt; 2700 parts of pure water;

[0068] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0069] Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salts, adding lactic acid to adjust the pH to 5.4, crushing the malt and putting it into a saccharification pot, adding protease and keeping it at 50°C for 10min to 20min for protein enzymolysis; then heating it to 63°C and keeping it for 45min, heating it to 68°C and keeping it for 15min for saccharification, then heating it to 76°C and keeping it for 10min to complete saccharification, and finally adding 2 parts of clarifier beer silica gel and 2 parts of PVPP for adsorption;

[0070] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0071] Step (4) adopts two-stage cooling to quickly cool the fermented wort to the fermentation temperature of 20° C. within 40 minutes, then add the fermented wort into the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0072] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days. The temperature is then lowered to 16°C and the remaining 2 portions of tea leaves are added. The temperature is maintained at 16°C and soaked for 5 days. After the soaking is completed, the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and the mixture is matured at 8°C for 20 days to obtain green tea beer.

[0073] In summary, the present invention has the following advantages:

[0074] 1. The present invention controls the temperature and pH value in the saccharification stage before adding tea leaves to achieve the optimal conditions for protease hydrolysis, and then hydrolyzes the protein in the saccharification solution to split the long-chain protein into amino acids and polypeptides. Since amino acids and polypeptides cannot be hydrogen-bonded with polyphenols, it can avoid the complexation of various polyphenols in beer with proteins to form turbidity at low temperatures; in the absence of protein, various polyphenols in beer cannot form flocs, thereby greatly improving the clarity of the final beer product at room temperature or low temperature. In addition, since protease cannot completely decompose all proteins, beer silica gel and PVPP are used for adsorption after enzymolysis. The adsorption material can adsorb polyphenols and can also adsorb heat-coagulated and denatured proteins, thereby further reducing the protein content in the solution.

[0075] In the beer preparation process, there are often heat coagulation and condensation processes, that is, after saccharification and boiling, part of the protein will be heat coagulated and precipitated, and it will generally be filtered at this time. After adding tea leaves, it will be cooled to a relatively low fermentation temperature, and part of the protein will also condense and precipitate. Both heat coagulation and condensation precipitation can be removed by filtration or precipitation. However, at this time, the solution still contains proteins that cannot be precipitated by heat coagulation or condensation. The present invention can break the chain of proteins that cannot be precipitated by heat coagulation or condensation by enzymatically hydrolyzing proteins in the saccharification stage, thereby reducing the total amount of proteins in the solution that can be complexed with polyphenols.

[0076] 2. At the same time, before adding tea leaves, not only most of the protein is removed by enzymatic hydrolysis, but also bran polyphenols are adsorbed by PVPP and beer silica gel. Due to the large amount of malt used, removing bran polyphenols in the raw material can greatly reduce the total amount of polyphenols in beer, reduce bitterness, and retain more tea polyphenols and other flavor substances in tea, making the tea flavor in tea beer more intense.

[0077] 3. The present invention adjusts the inorganic salt component of the fermented wort, and at the same time, through rapid cooling, the condensed protein in the fermentation tank can be precipitated more easily. The faster the cooling, the better the protein precipitation effect, and the easier it is to form condensed flocs of protein, which can make the condensed flocs easier to separate and discharge from the fermented wort; when more protein is precipitated, the protein content in the beer is reduced, and the clarity of the beer can be further improved.

[0078] 4. In order to improve and increase the flavor level of beer, the present invention adopts beer yeast Dusseldorf safalek-97. Under the fermentation action of specific yeast, the glucoside components in tea leaves can be fully decomposed into flavor substances such as linalool and geraniol, significantly increasing the content of the two substances in the solution, thereby further enhancing the flavor of tea beer. DETAILED DESCRIPTION

[0079] The invention discloses a method for preparing green tea beer, comprising the following steps:

[0080] Step (1) Prepare the raw materials by weight:

[0081] 400 parts of malt, 2 to 3 parts of hops, 1 to 2 parts of brewer's yeast;

[0082] 3 to 6 parts of tea leaves; 1 to 2 parts of lactic acid; 2 to 5 parts of clarifier;

[0083] The clarifier is selected from beer silica gel or PVPP;

[0084] 1 to 2 parts of inorganic salt; 2500 to 3000 parts of pure water;

[0085] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1-2:5-6;

[0086] Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salt, adding lactic acid to adjust the pH to 5.3 to 5.5, crushing the malt and putting it into a saccharification pot, adding protease and keeping it at 50°C to 55°C for 10min to 20min for protein enzymolysis; then heating it to 60°C to 65°C and keeping it for 40min to 60min, then heating it to 65°C to 70°C and keeping it for 10min to 20min for saccharification, then heating it to 75°C to 78°C and keeping it for 10min to 15min to complete saccharification; then adding a clarifier for adsorption to obtain a saccharified liquid;

[0087] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 1 to 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0088] Step (4) adopts two-stage cooling to quickly cool the fermented wort to a fermentation temperature of 18°C ​​to 22°C within 30min to 45min, then add the fermented wort to a fermentation tank for cooling and precipitation for 8h to 10h, and discharge the cold flocculants;

[0089] After the cold flocculants are discharged in step (5), brewer's yeast is inoculated in a fermentation tank and fermented at 18°C ​​to 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 to 7 days, then the temperature is lowered to 17°C and the remaining tea leaves are added and soaked for 3 to 5 days. After the soaking is completed, the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and then the green tea beer is obtained after aging at 8°C for 15 to 20 days.

[0090] Example 1

[0091] A method for preparing green tea beer comprises the following steps:

[0092] Step (1) Prepare the raw materials by weight:

[0093] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0094] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0095] 1.5 parts of inorganic salt; 2700 parts of pure water;

[0096] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0097] Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salts, adding lactic acid to adjust the pH to 5.4, crushing the malt and putting it into a saccharification pot, adding protease and keeping it at 50°C for 16 minutes for protein enzymolysis; then heating it to 63°C and keeping it for 45 minutes, heating it to 68°C and keeping it for 15 minutes for saccharification, and then heating it to 76°C and keeping it for 10 minutes to complete the saccharification, and finally adding 2 parts of beer silica gel and 2 parts of PVPP as clarifiers for adsorption;

[0098] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0099] Step (4) adopts two-stage cooling to quickly cool the fermented wort to the fermentation temperature of 20° C. within 40 minutes, then add the fermented wort into the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0100] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days. The temperature is then lowered to 16°C and the remaining 2 portions of tea leaves are added. The temperature is maintained at 16°C and soaked for 5 days. After the soaking is completed, the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and the mixture is matured at 8°C for 20 days to obtain green tea beer.

[0101] Experimental Example 1: Effects of different treatment processes on the turbidity of fermented beer

[0102] Experimental Example 11:

[0103] A method for preparing green tea beer comprises the following steps:

[0104] Step (1) Prepare the raw materials by weight:

[0105] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0106] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0107] 1.5 parts of inorganic salt; 2700 parts of pure water;

[0108] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0109] Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salts, adding lactic acid to adjust the pH to 5.4, crushing the malt and putting it into the saccharification pot; then heating it to 63°C and keeping it for 45 minutes, heating it to 68°C and keeping it for 15 minutes for saccharification, then heating it to 76°C and keeping it for 10 minutes to complete the saccharification, and finally adding 2 parts of beer silica gel and 2 parts of PVPP as clarifiers for adsorption;

[0110] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0111] Step (4) adopts two-stage cooling to quickly cool the fermented wort to the fermentation temperature of 20° C. within 40 minutes, then add the fermented wort into the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0112] After the cold flocculants are discharged in step (5), brewer's yeast is inoculated in a fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days. The temperature is then lowered to 16°C and the remaining 2 portions of tea leaves are added. The temperature is maintained at 16°C and soaked for 5 days. After the soaking is completed, the temperature is lowered to 2°C, the residue is removed after cooling and precipitation, and the green tea beer is obtained after aging at 8°C for 20 days.

[0113] Experimental Example 12:

[0114] A method for preparing green tea beer comprises the following steps:

[0115] Step (1) Prepare the raw materials by weight:

[0116] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0117] 4 parts of tea leaves; 1 part of lactic acid;

[0118] 1.5 parts of inorganic salt; 2700 parts of pure water;

[0119] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0120] Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salts, adding lactic acid to adjust the pH to 5.4, crushing the malt and putting it into the saccharification pot; then heating it to 63°C and keeping it for 45 minutes, heating it to 68°C and keeping it for 15 minutes to carry out saccharification, and then heating it to 76°C and keeping it for 10 minutes to complete the saccharification;

[0121] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0122] Step (4) adopts two-stage cooling to quickly cool the fermented wort to the fermentation temperature of 20° C. within 40 minutes, then add the fermented wort into the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0123] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days. The temperature is then lowered to 16°C and the remaining 2 portions of tea leaves are added. The temperature is maintained at 16°C and soaked for 5 days. After the soaking is completed, the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and the mixture is matured at 8°C for 20 days to obtain green tea beer.

[0124] Experimental Example 13:

[0125] A method for preparing green tea beer comprises the following steps:

[0126] Step (1) Prepare the raw materials by weight:

[0127] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0128] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0129] 1.5 parts of inorganic salt; 2700 parts of pure water;

[0130] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0131] Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salts, adding lactic acid to adjust the pH to 5.4, crushing the malt and putting it into the saccharification pot; then heating it to 63°C and keeping it for 45 minutes, heating it to 68°C and keeping it for 15 minutes to carry out saccharification, and then heating it to 76°C and keeping it for 10 minutes to complete the saccharification;

[0132] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0133] Step (4) adopts two-stage cooling to quickly cool the fermented wort to the fermentation temperature of 20° C. within 40 minutes, then add the fermented wort into the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0134] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days. The temperature is then lowered to 16°C and the remaining 2 parts of tea leaves are added. The temperature is maintained at 16°C and soaked for 5 days. After the soaking is completed, the temperature is lowered to 2°C, the residue is removed after cooling and precipitation, and 2 parts of clarifier beer silica gel and 2 parts of PVPP are added for adsorption. The green tea beer is then matured at 8°C for 20 days to obtain green tea beer.

[0135] Compared with Example 1, Experimental Example 11 omits the step of protein enzymolysis, but still retains the process step of adding 2 parts of clarifier beer silica gel and 2 parts of PVPP for adsorption in step (2). Experimental Example 12 reduces the process step of adding 2 parts of clarifier beer silica gel and 2 parts of PVPP for adsorption on the basis of Experimental Example 11. Experimental Example 13 omits the step of protein enzymolysis and the process step of using a clarifier for adsorption in step (2), but uses a clarifier for adsorption after fermentation is completed. The present invention tests the four types of tea beer obtained in Example 1 and Experimental Examples 11 to 13, and the clarity, i.e., turbidity, is tested using beer turbidity in accordance with national standards. The detection content of beer turbidity in the beer analysis method GB / T 4928-2008 is as follows.

[0136] Principle: Use Formazin standard turbidity solution to calibrate the turbidimeter and directly measure the turbidity of the beer sample, expressed in turbidity units EBC.

[0137] Instruments and reagents: Turbidimeter measuring range 0EBC~5EBC, graduation value 0.01EBC; hydrazine sulfate solution 10g / L; hexamethylenetetramine solution 100g / L; fulmarin standard turbidity stock solution; fulmarin standard turbidity working solution.

[0138] Analysis steps: Install and debug according to the instrument manual, and calibrate the turbidity meter with standard turbidity solution. Pour the sample with a temperature of 20℃±0.1℃ into the standard cup of the turbidity meter, put it into the turbidity meter for measurement, and read the reading directly. This method is the first method, and the measurement should be completed within 5 minutes after the sample is degassed. Or put the whole bottle of wine into the instrument, rotate it for one circle, and take the average value; this method is the second method, draw a cross on the bottle cap in advance, rotate it four times 90 manually, take the average value of the four readings and report the result, and the result is expressed to one decimal place.

[0139] The beer prepared by the methods disclosed in Example 1 and Experimental Examples 1 to 3 was subjected to the above analysis method, and the test results are as follows:

[0140] Group Turbidity value (EBC) Example 1 0.78 Experimental Example 11 1.66 Experimental Example 12 2.14 Experimental Example 13 1.52

[0141] In Example 1, by decomposing proteins, the protein content in the fermentation liquid that can be complexed with polyphenols is reduced, so that the protein content in the beer after fermentation is completed is very low. At the same time, after the bran polyphenols and part of the protein are absorbed in the early stage, the clarity of the fermentation liquid is very high, and the turbidity value is the lowest. Experimental Example 11 omits the step of protein enzymolysis, but still adsorbs part of the protein and polyphenols during the saccharification process, reduces the content of bran polyphenols, and is also conducive to reducing the total amount of floccules formed by complexing with proteins in the later stage. However, due to the overall high protein content, the protein can be complexed with the tea polyphenols added later, and a certain amount of complex can be formed at low temperatures. Experimental Example 12 does not perform protein decomposition, nor does it use adsorbent materials for adsorption, so the turbidity value is the highest. Experimental Example 13 uses an adsorbent material to adsorb the protein polyphenol complex after fermentation. The adsorption effect of Experimental Example 13 is actually related to the amount of adsorbent material used. Within a certain range, more adsorbent material will increase the total amount of adsorption, thereby having better clarity. In order to maintain the same amount of adsorbent material as other experimental examples, this Experimental Example 13 selected 2 parts of beer silica gel and 2 parts of PVPP for adsorption. The turbidity value after adsorption is slightly different from that of Experimental Example 11. It can be seen from the above experimental examples that protein mainly comes from malt. In the complexation of protein and polyphenols, protein is generally excessive; protein is gradually removed during saccharification, boiling, and hot and cold flocculation. However, due to differences in the types and properties of protein, it is not easy to remove all protein in the solution by boiling and hot and cold flocculation. Therefore, Example 1 of the present invention can greatly reduce the protein content in the fermentation process by removing most of the protein by enzymatic hydrolysis in the early stage, and then combining adsorption with adsorbent material adsorption, so that after fermentation, the tea polyphenols in the tea leaves have no protein to be complexed, and thus have good clarity at low temperatures.

[0142] Experimental Example 2: Effects of different cooling methods on protein precipitation results

[0143] Experimental Example 21: No Rapid Cooling

[0144] A method for preparing green tea beer comprises the following steps:

[0145] Step (1) Prepare the raw materials by weight:

[0146] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0147] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0148] 1.5 parts of inorganic salt; 2700 parts of pure water;

[0149] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0150] Step (2) crushing the malt and putting it into a saccharification pot, adding pure water and inorganic salts, heating to 50°C to 55°C, adding lactic acid to adjust the pH value to 5.4, and keeping it for 15 minutes; then adding protease and heating to 52°C for protein enzymolysis; then heating to 63°C and keeping it for 45 minutes, heating to 68°C and keeping it for 15 minutes for saccharification, and then heating to 76°C and keeping it for 10 minutes to complete saccharification, and finally adding 2 parts of beer silica gel and 2 parts of PVPP as clarifiers for adsorption;

[0151] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0152] Step (4) The fermented wort is cooled to a fermentation temperature of 20° C. within 90 to 100 minutes, and then the fermented wort is added to a fermentation tank for cooling and precipitation for 8 hours, and the cold flocculants are discharged.

[0153] Experimental Example 22: No Rapid Cooling

[0154] A method for preparing green tea beer comprises the following steps:

[0155] Step (1) Prepare the raw materials by weight:

[0156] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0157] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0158] 1.5 parts of inorganic salt; 2700 parts of pure water;

[0159] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0160] Step (2) crushing the malt and putting it into a saccharification pot, adding pure water and inorganic salts, heating to 50°C to 55°C, adding lactic acid to adjust the pH value to 5.4, and keeping it for 15 minutes; then adding protease and heating to 52°C for protein enzymolysis; then heating to 63°C and keeping it for 45 minutes, heating to 68°C and keeping it for 15 minutes for saccharification, and then heating to 76°C and keeping it for 10 minutes to complete saccharification, and finally adding 2 parts of beer silica gel and 2 parts of PVPP as clarifiers for adsorption;

[0161] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0162] Step (4) The fermented wort is cooled to a fermentation temperature of 20° C. within 3 to 4 hours, and then the fermented wort is added to a fermentation tank for cooling and precipitation for 8 hours, and the cold flocculants are discharged.

[0163] Experimental Example 23: No Inorganic Salt

[0164] A method for preparing green tea beer comprises the following steps:

[0165] Step (1) Prepare the raw materials by weight:

[0166] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0167] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0168] 2700 parts of pure water;

[0169] Step (2) crushing the malt and putting it into a saccharification pot, adding pure water and heating it to 48°C, adding lactic acid to adjust the pH value to 5.4, and keeping it for 15 minutes; then adding protease and heating it to 52°C for protein enzymolysis; then heating it to 63°C and keeping it for 45 minutes, heating it to 68°C and keeping it for 15 minutes for saccharification, and then heating it to 76°C and keeping it for 10 minutes to complete saccharification, and finally adding 2 parts of clarifier beer silica gel and 2 parts of PVPP for adsorption;

[0170] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0171] Step (4) adopts two-stage cooling to quickly cool the fermented wort to the fermentation temperature of 20° C. within 40 minutes, then add the fermented wort into the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants.

[0172] Experimental Example 24: No Inorganic Salt and No Rapid Cooling

[0173] A method for preparing green tea beer comprises the following steps:

[0174] Step (1) Prepare the raw materials by weight:

[0175] 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast;

[0176] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0177] 2700 parts of pure water;

[0178] Step (2) crushing the malt and putting it into a saccharification pot, adding pure water and heating it to 48°C, adding lactic acid to adjust the pH value to 5.4, and keeping it for 15 minutes; then adding protease and heating it to 52°C for protein enzymolysis; then heating it to 63°C and keeping it for 45 minutes, heating it to 68°C and keeping it for 15 minutes for saccharification, and then heating it to 76°C and keeping it for 10 minutes to complete saccharification, and finally adding 2 parts of clarifier beer silica gel and 2 parts of PVPP for adsorption;

[0179] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort;

[0180] Step (4) The fermented wort is cooled to a fermentation temperature of 20° C. within 3 to 4 hours, and then the fermented wort is added to a fermentation tank for cooling and precipitation for 8 hours, and the cold flocculants are discharged.

[0181] Compared with Example 1, in Experimental Example 21, the cooling time of the fermented wort in step (4) is extended; in Experimental Example 22, the cooling time of the fermented wort in step (4) is extended more; in Experimental Example 23, compared with Example 1, the inorganic salt component in Example 1 is not added, but a two-stage rapid cooling method is still adopted in step (4); in Experimental Example 24, compared with Example 1, no inorganic salt is added, and a two-stage rapid cooling method is not adopted, but a longer cooling method is adopted. After the above Experimental Examples 21 to 24 are processed in step (4), the fermented wort obtained after the cold flocculants are discharged is subjected to protein content detection. Currently, protein content detection includes the following four methods: Kjeldahl nitrogen determination method, biuret method, ultraviolet spectrophotometry, BCA method and Bradford method; the protein detection method adopted in the experimental examples of the present invention is the Kjeldahl nitrogen determination method; the specific detection results are as follows:

[0182] Group Protein content g / 100g Example 1 0.21 Experimental Example 21 0.30 Experimental Example 22 0.31 Experimental Example 23 0.24 Experimental Example 24 0.32

[0183] It can be seen from the above test results that the protein content in the fermented wort after rapid cooling in Example 1 of the present invention is the lowest. Experimental Example 21 has a longer cooling time than Experimental Example 22, which is a common cooling time for fermented wort in the industry. When the cooling time is greatly extended, the protein content of Experimental Example 21 and Experimental Example 22 is significantly higher than that of Example 1, but the protein content of Experimental Example 22 is slightly higher than that of Experimental Example 21. In Experimental Example 23, no inorganic salts were added, but a rapid cooling method was adopted. Its protein content increased significantly compared with that of Example 1, but it was still lower than that of Experimental Example 21 and Experimental Example 22. In Experimental Example 24, no inorganic salts were added, nor was a two-stage rapid cooling method adopted. Instead, a longer cooling method was adopted, which is equivalent to most of the processes in the prior art. The protein content of the fermented wort in Experimental Example 24 is not much different from that in Experimental Example 22, and there is no significant difference. It can be seen that under the condition of slow cooling, inorganic salts have little effect on the condensation and precipitation of protein; at the same time, compared with the other experimental examples, it can be seen that the protein can be better condensed and precipitated under the simultaneous presence of rapid cooling and inorganic salts, and inorganic salts have no significant effect on the protein condensate produced by slow cooling, that is, inorganic salts cannot cause more protein to precipitate during the slow cooling process; the rapid cooling method can make the protein in the fermented wort precipitate faster and more, and under the influence of inorganic salts, this effect is enhanced to a certain extent.

[0184] The present invention adjusts the inorganic salt components of the fermented wort, and at the same time, through a rapid cooling method, the condensed protein in the fermentation tank can be more easily precipitated. The faster the cooling, the better the protein precipitation effect, and the easier it is to form condensed flocs of the protein, so that the condensed flocs can be more easily separated and discharged from the fermented wort; when more protein is precipitated, the protein content in the beer is reduced, and the clarity of the beer can be further improved.

[0185] Glycosides are composed of aglycones and sugar groups, among which aglycones are flavor active substances with a characteristic fruity aroma. There are also many glycosides in tea. For example, linalool, an important aroma substance in tea, has a lily-like aroma, and geraniol has a rose-like aroma. They are among the aroma substances with higher content in tea and exist in the form of glucoside in the tea tree.

[0186] The present invention selects a specific yeast strain Dusseldorf safale k-97, which can produce glucosidase. Glucosidase can hydrolyze glycoside substances in tea leaves, and after hydrolysis, floral and fruity aromas can be released in fermented wine. Glucosidase produced by brewer's yeast can further hydrolyze glucosides to produce linalool and geraniol aglycones, thereby producing additional different floral and fruity aromas, thereby increasing the layering of beer.

[0187] Experimental Example 3: Effects of different yeasts on glycoside decomposition products in tea

[0188] Experimental Example 3 sets up multiple control groups. The control groups select other commonly used brewer's yeasts for comparison with the yeast strain Dusseldorf safale k-97 of the present invention. The fermentation substrate in the experiment is tea fermentation broth; several yeasts are used for fermentation, and then the contents of linalool and geraniol after fermentation are detected and compared. Since the saccharification efficiency of malt is affected by various factors, and malt and hops also contain similar glycosides, in order to ensure the experimental results, malt and hops are not added to the tea fermentation broth, and no saccharification step is performed. The malt is replaced with a solid malt extract that is easy to quantify, and the hops are replaced with fresh tea leaves.

[0189] Preparation of tea fermentation liquid: 200 parts of malt extract are placed in a saccharification pot, 2300 parts of pure water and 1.5 parts of inorganic salt are added, and lactic acid is added to adjust the pH to 5.4, and heated to boiling and maintained for 60 minutes. Tea leaves are added in the last 5 minutes of boiling. The mixed liquid is cooled to the fermentation temperature of 20°C.

[0190] Experimental Example 3

[0191] Step (1) Prepare the raw materials by weight:

[0192] 200 parts of wheat extract, 1 part of brewer's yeast Dusseldorf safale k-97;

[0193] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0194] 1.5 parts of inorganic salt; 2300 parts of pure water;

[0195] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0196] Step (2) adding malt extract and inorganic salts to pure water, and adding lactic acid to adjust the pH value to 5.4,

[0197] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; adding tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves and heat-dispersed protein from the saccharified liquid to obtain tea fermentation liquid; adding clarifiers 2 parts of beer silica gel and 2 parts of PVPP for adsorption;

[0198] Step (4) adopts two-stage cooling to quickly cool the tea fermentation liquid to the fermentation temperature of 20° C. within 40 minutes, then add the tea fermentation liquid to the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0199] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days; then the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and then the tea beer is obtained after aging at 8°C for 20 days.

[0200] Experimental Example 31: No tea leaves added

[0201] Step (1) Prepare the raw materials by weight:

[0202] 200 parts of wheat extract, 1 part of brewer's yeast Dusseldorf safale k-97;

[0203] 1 part of lactic acid; 2 parts of beer silica gel and 2 parts of PVPP as clarifier;

[0204] 1.5 parts of inorganic salt; 2300 parts of pure water;

[0205] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0206] Step (2) adding malt extract and inorganic salts to pure water, and adding lactic acid to adjust the pH value to 5.4,

[0207] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; adding tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves and heat-dispersed protein from the saccharified liquid to obtain tea fermentation liquid; adding clarifiers 2 parts of beer silica gel and 2 parts of PVPP for adsorption;

[0208] Step (4) adopts two-stage cooling to quickly cool the tea fermentation liquid to the fermentation temperature of 20° C. within 40 minutes, then add the tea fermentation liquid to the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0209] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days; then the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and then the tea beer is obtained after aging at 8°C for 20 days.

[0210] Experimental Example 32: Adding a small amount of tea leaves

[0211] Step (1) Prepare the raw materials by weight:

[0212] 200 parts of wheat extract, 1 part of brewer's yeast Dusseldorf safale k-97;

[0213] 1 part of tea leaves; 1 part of lactic acid; 2 parts of beer silica gel and 2 parts of PVPP as clarifiers;

[0214] 1.5 parts of inorganic salt; 2300 parts of pure water;

[0215] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0216] Step (2) adding malt extract and inorganic salts to pure water, and adding lactic acid to adjust the pH value to 5.4,

[0217] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; adding tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves and heat-dispersed protein from the saccharified liquid to obtain tea fermentation liquid; adding clarifiers 2 parts of beer silica gel and 2 parts of PVPP for adsorption;

[0218] Step (4) adopts two-stage cooling to quickly cool the tea fermentation liquid to the fermentation temperature of 20° C. within 40 minutes, then add the tea fermentation liquid to the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0219] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days; then the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and then the tea beer is obtained after aging at 8°C for 20 days.

[0220] Experimental Example 33: Replacement of brewer's yeast without glucosidase

[0221] Step (1) Prepare the raw materials by weight:

[0222] 200 parts of wheat extract, 1 part of brewer's yeast Dusseldorf safale WB-06;

[0223] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0224] 1.5 parts of inorganic salt; 2300 parts of pure water;

[0225] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0226] Step (2) adding malt extract and inorganic salts to pure water, and adding lactic acid to adjust the pH value to 5.4,

[0227] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; adding tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves and heat-dispersed protein from the saccharified liquid to obtain tea fermentation liquid; adding clarifiers 2 parts of beer silica gel and 2 parts of PVPP for adsorption;

[0228] Step (4) adopts two-stage cooling to quickly cool the tea fermentation liquid to the fermentation temperature of 20° C. within 40 minutes, then add the tea fermentation liquid to the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0229] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days; then the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and then the tea beer is obtained after aging at 8°C for 20 days.

[0230] Experimental Example 34: Cooling down after fermentation and adding tea leaves

[0231] Step (1) Prepare the raw materials by weight:

[0232] 200 parts of wheat extract, 1 part of brewer's yeast Dusseldorf safale k-97;

[0233] 4 parts of tea leaves; 1 part of lactic acid; 2 parts of clarifier beer silica gel, 2 parts of PVPP;

[0234] 1.5 parts of inorganic salt; 2300 parts of pure water;

[0235] The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5;

[0236] Step (2) adding malt extract and inorganic salts to pure water, and adding lactic acid to adjust the pH value to 5.4,

[0237] Step (3) boiling the saccharified liquid and keeping it for 60 minutes; filtering it by cyclotron sedimentation method to separate the impurities including the heat-dissolved protein from the saccharified liquid to obtain tea fermentation liquid; adding clarifiers 2 parts of beer silica gel and 2 parts of PVPP for adsorption;

[0238] Step (4) adopts two-stage cooling to quickly cool the tea fermentation liquid to the fermentation temperature of 20° C. within 40 minutes, then add the tea fermentation liquid to the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants;

[0239] After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days. The temperature is then lowered to 2°C and tea leaves are added and maintained for 5 days. After cooling and precipitation, the residue is discharged and the fermentation is further aged at 8°C for 20 days to obtain tea beer.

[0240] Compared with Experimental Example 3, in Experimental Example 31, no tea leaves were used in step (1); in Experimental Example 32, the amount of tea leaves used in step (1) was 1:4; in Experimental Example 33, the yeast used in step (1) was a strain that did not contain glucosidase compared with Experimental Example 3; in Experimental Example 34, no tea leaves were added for boiling in step (3), and tea leaves were added after fermentation and slag removal in step (5). The tea beer obtained in Experimental Examples 31 to 33 was tested for the contents of linalool and geraniol. The main methods for detecting volatile organic compounds include olfaction-gas chromatography, Fourier transform infrared, photoionization detection, and the like. The content of volatile aroma substances used in the experimental examples of the present invention was detected by gas chromatography; the type of volatile substances was detected by olfaction, and was evaluated by a sensory evaluation team composed of 5 tea tasters. The specific test results are as follows:

[0241]

[0242]

[0243] From the above test results, it can be seen that the tea beer fermented after boiling and adding tea leaves in Experimental Example 3 of the present invention has the highest content of linalool and geraniol. In Experimental Example 31, no tea leaves were added, and the two substances were not detected. In Experimental Examples 33 and 34, the yeast used in the former does not have the ability to produce glucose lyase, and the latter added tea leaves after fermentation. The detected linalool and geraniol are produced by hydrolysis of the hydrolytic enzymes in the tea leaves, and the content is significantly lower than that in Experimental Example 3; In Experimental Example 32, the amount of tea leaves added is reduced to 1 / 4 of that in Example 3, but due to the fermentation of yeast, the released linalool and geraniol are close to 1 / 2 of that in Experimental Examples 33 and 34.

[0244] It can be seen that under the fermentation of specific yeast, the glucoside components in tea leaves can be fully decomposed into aromatic substances such as linalool and geraniol, which significantly increases the content of the two substances in the solution, thereby further enhancing the aroma of tea beer.

Claims

1. A method for preparing green tea beer, characterized in that: The following steps are involved: Step (1) Prepare the raw materials by weight: 400 parts of malt, 2 to 3 parts of hops, 1 to 2 parts of brewer's yeast; 3 to 6 parts of tea leaves; 1 to 2 parts of lactic acid; 2 to 5 parts of clarifier; 1 to 2 parts of inorganic salt; 2500 to 3000 parts of pure water; The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1-2:5-6; Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salts, adding lactic acid to adjust the pH value, crushing the malt and putting it into the saccharification pot, adding protease and maintaining the temperature at 50°C to 55°C for protein enzymolysis; then heating it up for saccharification until saccharification is completed; after saccharification is completed, adding a clarifier for adsorption to obtain a saccharified liquid; Step (3) boiling the saccharified liquid, adding hops and a portion of tea leaves after boiling; filtering to separate the impurities including tea leaves, hops, and heat-dissociated protein from the saccharified liquid to obtain fermented wort; Step (4) adopts two-stage cooling to quickly cool the fermented wort to a fermentation temperature of 18°C ​​to 22°C within 30min to 45min, then add the fermented wort to a fermentation tank for cooling and precipitation, and discharge the cold flocculants; After the cold flocculants are discharged in step (5), brewer's yeast is inoculated in the fermentation tank. After the fermentation is completed, the remaining tea leaves are added and soaked for several days, and then the temperature is lowered to cool and settle to discharge the residue; and then the green tea beer is obtained by ripening.

2. The method for preparing green tea beer according to claim 1, characterized in that: The raw materials prepared in step (1) include, by weight: 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast; 4 parts of tea leaves; 1 part of lactic acid; 4 parts of clarifier; 1.5 parts of inorganic salt; 2700 parts of pure water; Among them, the inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each portion of inorganic salt is 5:1:5.

5.

3. The method for preparing green tea beer according to claim 1, characterized in that: The clarifier in step (1) is beer silica gel, PVPP or a mixed clarifier of beer silica gel and PVPP mixed in any proportion.

4. The method for preparing green tea beer according to claim 1, characterized in that: The specific operation process in step (2) is as follows: Put pure water into a saccharification pot, heat it to 50℃~55℃, add inorganic salt, add lactic acid to adjust the pH to 5.3~5.5, crush the malt and put it into the saccharification pot, add protease and keep it at 50℃~55℃ for 10min~20min for protein enzymolysis; then heat it to 60℃~65℃ and keep it for 40min~60min, then heat it to 65℃~70℃ and keep it for 10min~20min for saccharification, then heat it to 75℃~78℃ and keep it for 10min~15min to complete saccharification; then add a clarifier for adsorption to obtain a saccharified liquid.

5. The method for preparing green tea beer according to claim 1, characterized in that: The specific operation process in step (3) is as follows: The saccharification liquid is boiled and kept for 60 minutes; hops are divided into three parts, and one part of hops is added at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then 1 to 2 parts of tea leaves are added at 50 minutes after boiling; then cyclotron sedimentation method is used for filtering to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharification liquid to obtain fermented wort.

6. The method for preparing green tea beer according to claim 1, characterized in that: In the step (4), the cold flocculants in the fermentation tank are discharged after cooling and settling for 8 to 10 hours.

7. The method for preparing green tea beer according to claim 1, characterized in that: In the step (5), the fermentation is first carried out at 18°C ​​to 20°C, and the substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 to 7 days, and then the temperature is lowered to 17°C and the remaining tea leaves are added and soaked for 3 to 5 days; after the soaking is completed, the temperature is lowered to 2°C, and the residue is removed after cooling and precipitation, and then the green tea beer is obtained after aging at 8°C for 15 to 20 days.

8. A method for preparing green tea beer, characterized in that: The following steps are involved: Step (1) Prepare the raw materials by weight: 400 parts of malt, 2.5 parts of hops, 1 part of brewer's yeast; 4 parts of tea leaves; 1 part of lactic acid; 4 parts of clarifier; 1.5 parts of inorganic salt; 2700 parts of pure water; The inorganic salt includes calcium sulfate, magnesium sulfate and calcium chloride, and the mass ratio of calcium sulfate, magnesium sulfate and calcium chloride in each inorganic salt is 5:1:5.5; Step (2) putting pure water into a saccharification pot, heating it to 50°C to 55°C, adding inorganic salts, adding lactic acid to adjust the pH to 5.4, crushing the malt and putting it into a saccharification pot, adding protease and keeping it at 50°C for 10min to 20min for protein enzymolysis; then heating it to 63°C and keeping it for 45min, heating it to 68°C and keeping it for 15min for saccharification, then heating it to 76°C and keeping it for 10min to complete saccharification, and finally adding 2 parts of clarifier beer silica gel and 2 parts of PVPP for adsorption; Step (3) boiling the saccharified liquid and keeping it for 60 minutes; dividing hops into three parts, adding one part of hops at 30 minutes, 45 minutes and 60 minutes after boiling respectively, and then adding 2 parts of tea leaves at 50 minutes after boiling; filtering by cyclotron sedimentation method to separate impurities including tea leaves, hops and heat-dispersed protein from the saccharified liquid to obtain fermented wort; Step (4) adopts two-stage cooling to quickly cool the fermented wort to the fermentation temperature of 20° C. within 40 minutes, then add the fermented wort into the fermentation tank for cooling and precipitation for 8 hours, and discharge the cold flocculants; After the cold flocculants are discharged in step (5), brewer's yeast is introduced into the fermentation tank and fermented at 20°C. The substrate concentration is detected during the fermentation process. When the fermentation end point is detected, the temperature is raised to 22°C and maintained for 5 days. The temperature is then lowered to 16°C and the remaining 2 portions of tea leaves are added. The temperature is maintained at 16°C and soaked for 5 days. After the soaking is completed, the temperature is lowered to 2°C, the residue is discharged after cooling and precipitation, and the mixture is matured at 8°C for 20 days to obtain green tea beer.

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