How to formulate beer fermentation process

The formulation of the beer fermentation process has many aspects, which are related to the fermentation method, temperature, sugar reduction rate, time, yeast, cold coagulation discharge, CO2, post-treatment and many other aspects.

 Regulations on fermentation methods 

There are many beer fermentation methods, such as one-tank method, two-tank method (fermentation and wine storage are carried out separately), post-processing method after pouring tanks, etc., and the process needs to be determined according to different methods. For example, the one-pot method is a commonly used method in the production of beer industry in my country. The main fermentation and post-fermentation, also known as wine storage (CO₂ saturation, clarification, and taste maturity), are all completed in the same tank. Process formulation includes cold wort temperature, yeast species, yeast inoculation, fermentation process temperature control, sugar reduction speed control, fermentation cycle time control, sealing sugar content, sealing time control, sealing pressure control, cooling and wine storage. control and many others.

As the name implies, the two-tank method needs to be carried out in two vessels, and the processes of the fermentation tank and the wine storage tank need to be formulated separately. Although the content and ideas are basically the same, the process parameters are not necessarily the same.

 Process regulations for the temperature in the fermentation stage 

Temperature control in the fermentation stage is the main content of the formulation and adjustment of the fermentation process. Different yeast species, different beer types, different fermentation production methods, and different fermentation stages have different temperature parameters. For example, for high-concentration fermentation, a relatively high main fermentation temperature is generally recommended. For example, when the original wort concentration reaches above 14°P, the commonly used main fermentation temperature is 12°C, and special yeast performance cultivation is required. The main fermentation temperature of 10°C or below is mostly used for low-temperature and long-term fermentation varieties such as "Lager"; the so-called high-temperature fermentation usually refers to the case where the main fermentation temperature exceeds 12°C.

 Process regulations for the rate of fermentation and hypoglycemia 

The speed of sugar reduction is directly related to the fermentation production cycle and the inherent quality and flavor of beer, and is an important control content. The speed of sugar reduction is related to the quality of yeast, yeast quantity and fermentation temperature, and is related to the fermentable performance of wort. Usually, in the high foaming period of fermentation of Lager type beer, the daily sugar reduction rate should not exceed 2°P, and the highest should not exceed 2.5°P (referring to the apparent sugar content). Under normal conditions, 5d fermentation time and 5d reduction diacetyl time can already ensure the realization of fermentation degree. If the sugar reduction rate is too fast or too slow, it means that the fermentable performance of the wort, the amount of yeast added, the oxygenation conditions, the state of the yeast and the number of reproductive yeast cells, including the cooling temperature control and the main fermentation temperature control, have appeared. Some issues that need attention should be analyzed and resolved in a timely manner.

 The process regulation of fermentation cycle time 

The fermentation cycle time starts from the time when the large tank enters the tank. After fermentation, wine storage, and beer filtering empty tanks, all the time for preparing for the second tank entry is a process content that is closely related to product variety and product quality. In the above process cycles, most of the process times are very close, and the difference is relatively large in the cold storage time, which varies from 3 to 28 days. Usually, the varieties with relatively large output use a relatively short storage time, such as 3-7 days; for high-quality beer and export beer, the storage period of 21-28 days is usually used. For well-known brands of beer companies, it is recommended to use a longer storage period Period, such as 14 ~ 21d. In addition, the time and conditions of fermentation and warm storage should also be considered, including cooling speed, warm storage temperature, warm storage time, recovery of yeast, discharge of cold coagulation, and discharge of waste yeast, etc. Some breweries do not use the warm storage process, but A considerable number of beer companies and some foreign beer experts advocate the warm storage process.

 Process regulations for yeast recovery, washing and storage conditions 

"Recovery yeast" includes three aspects: recovery time, recovery method and recovery treatment. The most suitable time for the recovery of yeast is: the yeast has not been damaged by factors such as nutrient deficiency, negative effects of metabolites, wine temperature, etc., and has a relatively good relative activity time. At this time, the agglomeration of the yeast is not very tight, which is conducive to the dispersion after re-adding. Most of this time period is when the fermentation is completed and the diacetyl reduction is completed. However, if it cannot be used for addition immediately after recovery, it must be rapidly cooled to below 4°C to reduce its metabolic activity and facilitate preservation. If the recovery time is set in the condition that the yeast is relatively tightly coagulated, the relative activity is relatively poor, and the damage time of toxic and harmful substances is long, there may be a relatively large degree of aging and degradation, and the recovery value will be reduced.

The washing and storage conditions of the recovered yeast are also the contents that should be specified in the fermentation process, including low-temperature sterile water washing or acid washing, the number of washings, the specific requirements for the water or acid buffer used for washing, and the storage temperature and storage time. Specific provisions.

Fermentation systems brewing equipment

 Specific regulations for the discharge of cold solids 

The discharge of cold suspected solids should be discharged once every 12hr or 24hr when the wort tank is full, and the discharged yeast (for those not recycled) should be discharged once at the initial stage of pressure boosting. However, considering the problem of beer loss, the discharge frequency can be gradually increased in the order from high temperature to low temperature. Especially during the cold storage period, try to discharge as much as possible, which is beneficial to the filtration of beer, improving abiotic stability, and improving the taste. Therefore, there should be specific regulations on the discharge of cold coagulation and yeast in the fermentation process.

 CO₂ recovery, CO₂ washing, CO₂ saturation process 

Beer enterprises with CO2 recovery equipment should have CO2 recovery process regulations, including recovery time, recovery pressure, recovery purity regulations, etc.

CO₂ washing is very beneficial to reduce the content of acetaldehyde, S-containing compounds and other unpleasant flavor substances, and foreign beer companies attach great importance to this operation. Including CO₂ washing in the fermentation tank, CO₂ washing in the wine storage tank, and in the case of pouring the tank, it can also be carried out after the pouring of the tank, but the interval time of CO₂ washing and the time and speed of each washing should be specified. , temperature, saturation, etc. CO₂ saturation can be divided into two forms: in-tank saturation and online saturation, which are related to the fermentation method and the use of equipment.

BBT bright beer tanks

 Process regulations for post-fermentation treatment (Conditioning) 

Post-fermentation treatment is a process measure commonly used in fermentation process to adjust beer quality and uniform beer quality. Its contents include improving the clarity of the fermentation broth, improving the antioxidant properties of beer, uniformizing the flavor and taste of the fermentation broth, adjusting the CO₂ content, improving abiotic stability and foam stability, etc.

 Regulations on process control points and sampling time 

The regulation of process control points and sampling points in the fermentation process is the basis for controlling the fermentation process and understanding the effect of the fermentation process. Fermentation process control points can include wort cooling, initial fermentation, high foam fermentation, diacetyl reduction, fermentation broth cooling, yeast recovery and cold storage and other key process time or time periods; sampling time should be consistent with process control points , and specify the content of sample analysis and control standards for different sampling times.