Liquid yeast preserving fluid and application thereof

Abstract

The invention belongs to the technical field of saccharomycetes preservation, and particularly relates to a liquid saccharomycetes preservation solution and application thereof. The preserving fluid provided by the invention comprises 1-5wt% of sodium chloride, 15-35% v / v of glycerol, a pH regulator and the balance of water, wherein the pH value of the preserving fluid is 3.6-4.5; the pH regulator comprises lactic acid and / or phosphoric acid. Sodium chloride can increase osmotic pressure of the preserving fluid and inhibit fermentation of liquid saccharomycetes; glycerin has an anti-freezing effect and can maintain the activity of liquid yeast cells; the pH value of the preserving fluid is limited, so that fermentation of liquid saccharomycetes can be inhibited, the safety of the preserving fluid is kept, and infectious microbe infection is avoided. The preservation solution provided by the invention can be used for transporting the liquid yeast for 5-7 days at the normal temperature of 35 DEG C, is not easy to ferment and explode in the normal-temperature transportation process, is long in transportation time, convenient to operate and good in activity when being used again, and can be used after being transported, and the death rate of the liquid yeast can be kept at a relatively low level.

Description

Technical Field

[0001] The invention belongs to the technical field of yeast preservation, and in particular relates to a liquid yeast preservation solution and application thereof. Background Art

[0002] At present, the scale of beer in the market is gradually expanding. Small breweries and brewpubs have high requirements for the flavor of beer. They hope to have flavor characteristics different from those of large breweries, which is inseparable from different yeast strains. At present, the market generally buys dry powder yeast for use, which is easy to store and transport. However, dry powder yeast is generally used in large quantities, with high costs, and is produced in large quantities. Some niche yeast strains cannot be provided. In addition, dry powder yeast has a high mortality rate and poor activity. Compared with dry powder yeast, liquid yeast strains have higher activity than powdered yeast, and are currently used in many craft beer bars and small factories.

[0003] However, the suitable storage temperature of liquid yeast is 2-5°C, and the storage period at this temperature is 7-15 days. After exceeding this temperature and time, the mortality rate of yeast strains will increase significantly, so the transportation and storage of liquid yeast is more difficult. At present, the quality of liquid yeast is generally guaranteed by cold chain transportation and accelerated logistics transportation during transportation. However, during logistics transportation, the temperature control of cold chain vehicles is unstable, and there will be problems with temperature recovery, and the refrigeration temperature of most vehicles may not reach 2-5°C; if the delivery distance is far, the logistics transportation time is too long, and there will be problems exceeding the optimal storage period, so the product quality of liquid yeast cannot be guaranteed when it is transported to the customer. In addition, even if the product quality is good when it is transported to the customer, if the customer does not use it in time after receiving the goods, it is necessary to use cold storage or refrigerators for storage. The storage temperature and storage period must also be controlled during the storage process, otherwise the activity of liquid yeast will decrease during use, affecting its use. Therefore, it is necessary to expand the optimal storage temperature range of liquid yeast and extend the storage period. Summary of the invention

[0004] The purpose of the present invention is to provide a liquid yeast preservation solution and an application thereof, which can preserve or transport liquid yeast for 5 to 7 days at room temperature of 35°C, is not easy to ferment and explode during the preservation or transportation process, has good activity when used after preservation or transportation, and improves the taste and flavor of beer during the preparation process.

[0005] The present invention provides a liquid yeast preservation solution, which comprises 1-5wt.% sodium chloride, 15-35% v / v glycerol, a pH regulator and the balance of water; the pH value of the liquid yeast preservation solution is 3.6-4.5;

[0006] The pH adjuster includes lactic acid and / or phosphoric acid.

[0007] Preferably, the liquid yeast preservation solution comprises 2 wt.% sodium chloride, 20% v / v glycerol, a pH regulator and the balance water.

[0008] The present invention also provides the use of the liquid yeast preservation solution described in the above technical solution in the preservation and / or transportation of liquid yeast.

[0009] Preferably, the liquid yeast is stored and / or transported at a temperature of 0 to 35°C.

[0010] Preferably, the liquid yeast comprises ale yeast and / or lager yeast.

[0011] The present invention also provides a method for processing liquid yeast, including a method for storing and / or transporting liquid yeast.

[0012] The storage method comprises the following steps: mixing the liquid yeast with the liquid yeast storage solution described in the above technical solution, and storing the mixture at a temperature of 0 to 35°C;

[0013] The transportation method comprises the following steps: mixing the liquid yeast with the liquid yeast preservative solution described in the above technical solution, and transporting after packaging; the temperature during the transportation is 0-35°C.

[0014] Preferably, the method for preparing the liquid yeast comprises: culturing yeast using sterilized wort to obtain the liquid yeast.

[0015] Preferably, the culture temperature is 9-30°C and the culture time is 12-48 hours; and the wort is wort with a P of 6-14°C.

[0016] Preferably, after obtaining the liquid yeast, the method further comprises: concentrating the volume of the liquid yeast to 20% to 50% of the original volume.

[0017] The present invention also provides the use of liquid yeast treated by the treatment method described in the above technical solution in preparing beer.

[0018] Beneficial effects:

[0019] The present invention provides a liquid yeast preservation solution, which includes 1-5wt.% sodium chloride, 15-35% v / v glycerol, a pH regulator and the balance of water; the pH value of the liquid yeast preservation solution is 3.6-4.5; the pH regulator includes lactic acid and / or phosphoric acid. The present invention uses sodium chloride and glycerol as the components of the preservation solution, sodium chloride can increase the osmotic pressure of the liquid yeast preservation solution and inhibit yeast fermentation; glycerol has an antifreeze effect and can maintain the activity of yeast cells. The pH regulator is used to limit the pH value of the preservation solution, which can inhibit liquid yeast fermentation, maintain the safety of the preservation solution, and is not easy to be infected by miscellaneous bacteria. The liquid yeast preservation solution provided by the present invention can be used to maintain the transportation of liquid yeast for 5-7 days at room temperature of 35°C, is not easy to ferment and explode during transportation at room temperature, has a long transportation time, is easy to operate, has good activity when reused, and can be used again after transportation, and the mortality rate of liquid yeast can be maintained at a relatively low level.

[0020] Furthermore, beer prepared by treating liquid yeast with the liquid yeast preservation solution of the present invention has relatively low alcohol ester content, is not easy to get drunk after drinking, has very low acid content, and has relatively low acetaldehyde content, thus having better taste and flavor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0022] Figure 1 The growth of yeast after storage for 0 days in comparative example 1;

[0023] Figure 2 The growth of yeast after storage for 0 days in comparative example 2;

[0024] Figure 3 The growth of yeast in comparative example 3 after 0 days of storage;

[0025] Figure 4 The growth of yeast after storage for 0 days in Example 1;

[0026] Figure 5 The growth of yeast after storage for 7 days in comparative example 3;

[0027] Figure 6 The growth of yeast after 7 days of storage in Example 1;

[0028] Figure 7 The growth of yeast in comparative example 3 after storage for 10 days;

[0029] Figure 8 The growth of yeast after 10 days of storage in Example 1;

[0030] Fig. 9 The growth of yeast in comparative example 3 after 14 days of storage;

[0031] Fig.10 The growth of yeast after 14 days of storage in Example 1;

[0032] Fig.11 The growth of yeast in comparative example 4 after 0 days of storage;

[0033] Fig.12 The growth of yeast in comparative example 5 after 0 days of storage;

[0034] Fig.13 The growth of yeast in comparative example 6 after storage for 0 days;

[0035] Fig.14 The growth of yeast after storage for 0 days in Example 2;

[0036] Fig.15 The growth of yeast in comparative example 6 after 7 days of storage;

[0037] Fig.16 The growth of yeast after 7 days of storage in Example 2;

[0038] Fig.17 The growth of yeast in comparative example 6 after storage for 10 days;

[0039] Fig.18 The growth of yeast after 10 days of storage in Example 2;

[0040] Fig.19 The growth of yeast in comparative example 6 after 14 days of storage;

[0041] Fig. 20 The figure shows the growth of yeast after 14 days of storage in Example 2. DETAILED DESCRIPTION

[0042] The invention provides a liquid yeast preservation solution, which comprises 1-5wt.% sodium chloride, 15-35% v / v glycerol, a pH regulator and the remainder of water; the pH value of the liquid yeast preservation solution is 3.6-4.5; and the pH regulator comprises lactic acid and / or phosphoric acid.

[0043] In the present invention, the liquid yeast preservative solution includes 1-5wt.% sodium chloride. As an embodiment, the liquid yeast preservative solution of the present invention includes 2wt.% sodium chloride. The present invention uses sodium chloride as a component of the liquid yeast preservative solution, which can increase the osmotic pressure of the liquid yeast preservative solution and inhibit yeast fermentation. Sodium chloride is low in price and mild in effect, and can be used in food.

[0044] In the present invention, the liquid yeast preservative solution includes 15-35% v / v glycerol. As an embodiment, the liquid yeast preservative solution of the present invention includes 20% v / v glycerol. The present invention uses glycerol as a component of the liquid yeast preservative solution, which has an antifreeze effect and can maintain the activity of yeast cells. Glycerol has a mild effect and meets the GB 2760-2024 National Food Safety Standard for Food Additives.

[0045] In the present invention, the liquid yeast preservation solution includes a pH regulator; the pH regulator includes lactic acid and / or phosphoric acid. As an embodiment, the pH regulator of the present invention is lactic acid or phosphoric acid. The pH value of the liquid yeast preservation solution of the present invention is 3.6 to 4.5. As an embodiment, the pH value of the liquid yeast preservation solution of the present invention is 3.8 to 4.2; as another embodiment, the pH value of the liquid yeast preservation solution of the present invention is 4.0. The present invention uses a pH regulator to limit the pH value of the liquid yeast preservation solution, which can inhibit the fermentation of the liquid yeast, maintain the safety of the preservation solution, and prevent infection by foreign bacteria.

[0046] The sodium chloride in the yeast preservative solution of the present invention can increase the osmotic pressure of the liquid yeast preservative solution and inhibit yeast fermentation; glycerol has an antifreeze effect and can maintain the activity of yeast cells. The pH value of the preservative solution is limited by a pH regulator, which can inhibit yeast fermentation, maintain the safety of the preservative solution, and prevent infection by foreign bacteria. The liquid yeast preservative solution provided by the present invention can be used to transport liquid yeast for 5 to 7 days at room temperature of 35°C. It is not easy to ferment and explode during transportation at room temperature, has a long transportation time, is easy to operate, has good activity when reused, and can be used again after transportation. The mortality rate of liquid yeast can be maintained at a relatively low level.

[0047] In view of the effects of the liquid yeast preservative solution provided by the present invention, the use of the liquid yeast preservative solution in the preservation and / or transportation of liquid yeast also falls within the protection scope of the present invention.

[0048] In the present invention, as one embodiment, the temperature for storage and / or transportation of the liquid yeast is 0-35°C; as another embodiment, the temperature for storage and / or transportation of the liquid yeast is 0-30°C; as another embodiment, the temperature for storage and / or transportation of the liquid yeast is 10-30°C; as another embodiment, the temperature for storage and / or transportation of the liquid yeast is 20-30°C; as another embodiment, the temperature for storage and / or transportation of the liquid yeast is 25-30°C.

[0049] In the present invention, as an embodiment, the yeast is a liquid yeast. As an embodiment, the yeast includes ale yeast and / or lager yeast. As an embodiment, the ale yeast includes WB-06 dry powder yeast. The present invention has no strict requirements on the source of the yeast, and it can be purchased conventionally. In the embodiments of the present invention, ale yeast and / or lager yeast are only used as examples for illustration, and they cannot be understood as the entire protection scope of the present invention. The liquid yeast preservative solution of the present invention is suitable for the storage and / or transportation of any type of yeast.

[0050] The present invention also provides a method for processing liquid yeast, including a method for preserving and / or transporting liquid yeast.

[0051] In the present invention, the storage method comprises the following steps: mixing the liquid yeast with the liquid yeast storage solution described in the above technical solution, and storing at a temperature of 0 to 35°C. As an embodiment, the storage temperature of the present invention is 0 to 30°C; as another embodiment, the storage temperature is 10 to 30°C; as another embodiment, the storage temperature is 20 to 30°C; as another embodiment, the storage temperature is 25 to 30°C. As an embodiment, the storage time of the present invention is ≤14d; as another embodiment, the storage time of the present invention is 5 to 14d; as another embodiment, the storage time of the present invention is 7d.

[0052] In the present invention, the transportation method comprises the following steps: mixing the liquid yeast with the liquid yeast preservative solution described in the above technical solution, packaging and transporting; the temperature during the transportation is 0-35°C. As an embodiment, the temperature during the transportation of the present invention is 0-30°C; as another embodiment, the temperature during the transportation is 10-30°C; as another embodiment, the temperature during the transportation is 20-30°C; as another embodiment, the temperature during the transportation is 25-30°C. As an embodiment, the transportation time of the present invention is ≤14d; as another embodiment, the transportation time of the present invention is 5-14d; as another embodiment, the transportation time of the present invention is 7d.

[0053] As an embodiment, the present invention utilizes sterilized wort to culture yeast to obtain liquid yeast. In the present invention, as an embodiment, the culture temperature is 25°C and the time is 24h. As an embodiment, the wort is 11°P wort. The present invention has no strict requirements on the preparation method of the wort, and it can be prepared in a conventional manner in the art, such as using basic barley malt, saccharification, filtration, boiling, and secondary filtration to obtain the wort. As an embodiment, the sterilization temperature is 121°C and the time is 15min. The present invention utilizes sterilized wort to culture yeast, and the wort is easy to obtain and contains almost all the nutrients necessary for yeast growth, which is close to the state during subsequent beer fermentation. As an embodiment, after obtaining the liquid yeast, the present invention concentrates the volume of the liquid yeast to 20% to 50% of the original.

[0054] In the process of treating liquid yeast, the present invention does not need to use freeze drying technology, spray drying technology and granulation drying technology to make liquid yeast into dry powder yeast, which reduces the use of equipment, does not damage the activity of yeast, and retains the flavor of liquid yeast to the greatest extent. It can be transported at room temperature of 30°C for 5 to 7 days and then used again after transportation. The yeast mortality rate can still be kept at a relatively low level. The beer prepared by the liquid yeast treated by the treatment method of the present invention has relatively low alcohol esters, is not easy to get drunk after drinking, has very low acid content, and has relatively low acetaldehyde content, and has better taste and flavor.

[0055] The present invention also provides the use of liquid yeast treated by the treatment method described in the above technical solution in the preparation of beer. As an embodiment, the present invention uses the liquid yeast treated by the treatment method described in the above technical solution to ferment beer preparation raw materials to obtain beer. As an embodiment, the beer preparation raw materials of the present invention include 58% to 60% barley malt and 40% to 42% wheat malt; as another embodiment, the beer preparation raw materials of the present invention include 60% barley malt and 40% wheat malt. The present invention has no strict requirements on the preparation method of the beer, and conventional methods in the art can be used.

[0056] In order to further illustrate the present invention, a liquid yeast preservation solution and its application provided by the present invention are described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the protection scope of the present invention.

[0057] The materials used in this embodiment are as follows:

[0058] WB-06 dry powder yeast, purchased from Fermentis Yeast Co., Ltd., is an ale yeast with the product number SafbrewWB-06.

[0059] WB-34 / 70 dry powder yeast, purchased from Fermentis Yeast Co., Ltd., is a lager yeast with the product number Safbrew WB-34 / 70.

[0060] 8.5g / L normal saline: Dissolve 8.5g sodium chloride in 1000mL distilled water, divide into portions, sterilize at 121℃ for 15min, let cool and set aside.

[0061] 20g / L saline: Dissolve 20g of sodium chloride in 1000mL of distilled water, divide into portions, sterilize at 121℃ for 15min, let cool and set aside.

[0062] 11°P wort: Use basic barley malt, saccharify, filter, boil, and filter twice to prepare 11°P wort, then sterilize at 121℃ for 15min, let cool and set aside.

[0063] Glycerol solution: Food grade, sterilize at 121℃ for 15min, let cool and set aside.

[0064] Phosphoric acid solution: food grade.

[0065] Example 1

[0066] Put WB-06 dry powder yeast into sterilized 11°P wort, grow it at 25°C for 24 hours, and concentrate the volume of the yeast solution after 24 hours of growth to 50% of the original volume; add sterilized 20g / L saline to the concentrated yeast solution to make the sodium chloride content 2wt.%; add glycerol to make the ratio 20%, adjust the pH to 3.8, and store it at room temperature 25-30°C (add 14mL of 20g / L saline, 30mL of glycerol solution, and 0.02mL of phosphoric acid solution to every 100mL of yeast concentrate).

[0067] Comparative Example 1

[0068] Add 10 times the weight of 8.5g / L saline to WB-06 dry powder yeast and activate for 30 minutes. 。

[0069] Comparative Example 2

[0070] Put WB-06 dry powder yeast into sterilized 11°P wort and grow it at 25°C for 24 hours. Store the yeast solution after 24 hours of growth at room temperature.

[0071] Comparative Example 3

[0072] Put WB-06 dry powder yeast into the sterilized 11°P wort and grow it at 25℃ for 24 hours. Then, store the yeast solution directly in a refrigerator at 4℃ after 24 hours of growth.

[0073] Test Example 1

[0074] After the yeasts of Example 1 and Comparative Examples 1 to 3 were stored for a certain period of time, the supernatant was taken to calculate the yeast mortality rate. The results are shown in Tables 1 and Figures 1 to 10 shown.

[0075] Table 1 Yeast mortality test results (%)

[0076]

[0077] according to Figures 1 to 10 As can be seen from Table 1, the average mortality rate of WB-06 dry powder yeast after activation in Comparative Example 1 is 12.2%, which is relatively high. The average mortality rate of WB-06 dry powder yeast in Comparative Example 2 is 0%, which is not much different from the mortality rate at the beginning of storage in Example 1 and Comparative Example 3. After the storage starts according to different storage methods, the mortality rates of yeasts stored by the two different storage methods are different. The present invention can ensure room temperature transportation. After 7 days, the mortality rate of yeast is lower than that of yeast stored in cold storage. After 10 days, the mortality rate of yeast is not much different from that of yeast stored in cold storage. At the same time, if placed for 14 days, the mortality rate of yeast under the storage method of the present invention is higher than that of cold-stored yeast. Usually the transportation time is less than 10 days, which can meet the requirements.

[0078] Example 2

[0079] Put WB-34 / 70 dry powder yeast into sterilized 11°P wort, grow it at 25°C for 24 hours, and concentrate the volume of the yeast solution after 24 hours of growth to 50% of the original volume; add sterilized 20g / L saline to the concentrated yeast solution to make the sodium chloride content 2wt.%; add glycerol to make the ratio 20%, adjust the pH to 3.8, and store it at room temperature 25-30°C (add 14mL of 20g / L saline, 30mL of glycerol solution, and 0.02mL of phosphoric acid solution to every 100mL of yeast concentrate).

[0080] Comparative Example 4

[0081] Add 10 times the weight of 8.5g / L saline to WB-34 / 70 dry powder yeast and activate for 30 minutes. 。

[0082] Comparative Example 5

[0083] Put WB-34 / 70 dry powder yeast into sterilized 11°P wort and grow it at 25°C for 24 hours. Store the yeast solution after 24 hours of growth at room temperature.

[0084] Comparative Example 6

[0085] Put WB-34 / 70 dry powder yeast into the sterilized 11°P wort and grow it at 25°C for 24 hours. Then, store the yeast solution directly in a refrigerator at 4°C after 24 hours of growth.

[0086] Test Example 2

[0087] After the yeasts of Example 2 and Comparative Examples 4 to 6 were stored for a certain period of time, the supernatant was taken to calculate the yeast mortality rate. The results are shown in Tables 2 and Figures 11 to 20 shown.

[0088] Table 2 Yeast mortality test results (%)

[0089]

[0090] according to Figures 11 to 20 As can be seen from Table 2, the mortality rate of WB-34 / 70 dry powder yeast after activation in Comparative Example 4 is 45.8%, which is relatively high. The mortality rate of WB-34 / 70 dry powder yeast in Comparative Example 5 is 11.17% on average, which is not high. Compared with the mortality rates at the beginning of storage in Example 2 and Comparative Example 6, the three are not much different. After the storage starts according to different storage methods, the mortality rates of yeasts stored by the two different storage methods are different. The present invention can ensure room temperature transportation. After 7 days, the mortality rate of yeast is lower than that of cold-stored yeast. After 10 days, the mortality rate of yeast is not much different from that of cold-stored yeast. At the same time, if placed for 14 days, the mortality rate of yeast under the storage method of the present invention is slightly higher than that of cold-stored yeast. Usually the transportation time is less than 10 days, which can meet the requirements (since Example 2 and Comparative Examples 4 to 6 use yeast that is close to the expiration date, the dry powder yeast has a shelf life of three years, so the mortality rate is high).

[0091] Application Example 1

[0092] Beer was prepared using barley malt, wheat malt, beer hop particles (Qingdao Dahua), yeast stored for 7 days in Example 1, and water as raw materials using the following steps:

[0093] (1) 50 kg of barley malt and 35 kg of wheat malt were taken and humidified and ground. The ground materials were mixed with water in a ratio of 1 kg to 4 L. The material temperature was 50-55° C. and maintained for 30 min. The temperature was then raised to 65-72° C. and maintained for 60 min.

[0094] (2) Filter, wash and boil for 1 hour, add Qingdao Dahua three times during boiling, the weight proportion of the three additions is: 20%, 60% and 20%;

[0095] (3) After boiling, vortex precipitation is performed; then the mixture is cooled to 16-20° C., and the yeast stored for 7 days in Example 1 is added with oxygen to make the dissolved oxygen reach 8-9 mg / L and the yeast count in the full tank reach 5-10 million / mL. The mixture is fermented at 20-22° C. until the sugar content drops to 4.5-6° P. The mixture is sealed and the diacetyl is reduced to 0.1 mg / L. The mixture is cooled to about 0° C. and stored at 0-2° C. for 5-10 days to obtain beer.

[0096] Application Example 2

[0097] Beer was prepared in the same manner as in Application Example 1, with the only difference being that the yeast stored for 7 days in Example 1 used in Application Example 1 was replaced with the yeast treated in Comparative Example 1.

[0098] Application Example 3

[0099] Beer was prepared in the same manner as in Application Example 1, with the only difference being that the yeast stored for 7 days in Example 1 used in Application Example 1 was replaced with the yeast stored for 7 days in Comparative Example 3.

[0100] Test Example 3

[0101] Referring to Appendix C of GB / T4928-2008, the analysis method of enterprise self-control technical indicators, C.8 low boiling point aroma components, the types and contents of flavor substances in the beer obtained in Application Examples 1 to 3 were tested, and the results are shown in Table 3.

[0102] Table 3 Types and content of flavor substances in beer (μg / L)

[0103] project Application Example 1 Application Example 2 Application Example 3 Acetaldehyde 3.25513 8.67484 2.787048 Ethyl acetate 25.35817 12.35087 23.679381 Isobutyl acetate 0.14923 0.029663 0.068365 n-Propanol 15.70506 11.12575 8.79714 Isobutanol 24.81492 5.61179 9.848542 Isoamyl acetate 4.97254 0.85285 5.789036 Isoamyl alcohol 60.64232 45.94812 72.029639 Ethyl hexanoate 0.10053 0.10582 0.125323 Ethyl Caprylate 0.42118 0.25647 0.303369 Acetic acid 29.30408 69.12886 31.074406 Linalool 0.00594 0.01745 0.00627 Ethyl decanoate 0.04369 0.01708 0.012309 Isovalerate 0.10634 0.61485 0.228481 Phenethyl acetate 0.93522 0.14652 1.279069 Hexanoic acid 2.6562 2.06267 2.234342 Phenylethyl alcohol 19.30492 11.18235 38.973561 bitter 2.79506 4.45926 3.523498 Decanoic acid 0.18872 0.58577 0.078584 Isoamyl alcohol / ethyl acetate 2.39 4.55 3.35 Total alcohol / total ester 3.77 6.56 4.15

[0104] According to Table 3, compared with the beer prepared by using the yeast of Comparative Example 1 or 3, the beer prepared by using the yeast preserved by the present invention has relatively low alcohol ester, is not easy to get drunk after drinking, has very low acid content, and has relatively low acetaldehyde content. The beer prepared by the present invention has better taste and flavor, which is specifically manifested in low acetaldehyde content, low content of acids such as acetic acid, isovaleric acid, octanoic acid, and capric acid, and good taste; high content of ester aroma substances such as ethyl acetate, isobutyl acetate, and isoamyl acetate, strong ester aroma, and good taste.

[0105] Test Example 4

[0106] Sensory evaluation

[0107] The tasting panel consisted of 8 people, including 2 national-level tasting committee members and 6 people with long-term experience in beer technology and research and development. The tasting panel evaluated the beer obtained from Examples 1 to 3 from the perspectives of color, aroma, and taste according to the scoring criteria in Table 4. The results are shown in Table 5.

[0108] Table 4 Scoring criteria

[0109]

[0110] Table 5 Scoring results of different beers

[0111]

[0112]

[0113] It can be seen from Table 5 that compared with the beers prepared using the yeast of Comparative Examples 1 and 3, the beer prepared using the yeast preserved in the present invention has improved taste and flavor, which is significantly better than the taste and flavor of the beer prepared using dry yeast (Application Example 2), and tastes better than the beer prepared using yeast after cold chain transportation (Application Example 3).

[0114] It can be seen from the above content that the technical solution provided by the present invention can ensure that liquid yeast is not easy to ferment and explode again during transportation at room temperature (30°C), and the yeast mortality rate can be kept at a relatively low level if it is transported for 5 to 7 days and reused after transportation.

[0115] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A liquid yeast preservation solution, characterized in that: The liquid yeast preservation solution comprises 1-5 wt.% sodium chloride, 15-35% v / v glycerol, a pH regulator and the balance water; the pH value of the liquid yeast preservation solution is 3.6-4.5; The pH adjuster includes lactic acid and / or phosphoric acid.

2. The liquid yeast preservative according to claim 1, characterized in that: The liquid yeast preservation solution comprises 2wt.% sodium chloride, 20% v / v glycerol, a pH regulator and the balance water.

3. Use of the liquid yeast preservation solution according to claim 1 or 2 in the preservation and / or transportation of liquid yeast.

4. The use according to claim 3, characterized in that: The temperature for storing and / or transporting the liquid yeast is 0-35°C.

5. The use according to claim 3, characterized in that: The liquid yeast includes ale yeast and / or lager yeast.

6. A method for processing liquid yeast, including a method for preserving and / or transporting liquid yeast, characterized in that: The storage method comprises the following steps: mixing liquid yeast with the liquid yeast storage solution of claim 1 or 2, and storing at a temperature of 0 to 35°C; The transportation method comprises the following steps: mixing the liquid yeast with the liquid yeast preservative solution according to claim 1 or 2, and transporting after packaging; the temperature during the transportation is 0 to 35°C.

7. The processing method according to claim 6, characterized in that: The preparation method of the liquid yeast comprises: culturing yeast using sterilized wort to obtain the liquid yeast.

8. The processing method according to claim 7, characterized in that: The culture temperature is 9-30°C and the culture time is 12-48h; the wort has a P of 6-14°C.

9. The processing method according to claim 7, characterized in that: After obtaining the liquid yeast, the method further comprises: concentrating the volume of the liquid yeast to 20% to 50% of the original volume.

10. Use of liquid yeast treated by the treatment method according to any one of claims 6 to 9 in preparing beer.

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