Beer fermentation phase is a dynami

Beer fermentation phase is a dynamic process that must be controlled in accordance with certain technical requirements, especially the reaction temperature curve of fermentation process, in order to meet the quality requirements of the beer product. Temperature control curve of fermentation process is different depending on different beer varieties and different technological requirements. The typical curve of beer fermentation process is shown in Figure 2. As can be seen in the various stages of the curve shown below, the traditional fermentation process is generally divided into two main stages: primary fermentation and secondary fermentation. Firstly, the stage before primary fermentation stage belongs to the natural heating stage. Heating is generated by the heat released from fermentation itself. Thus, it does not need additional external control. In the primary fermentation stage, the typical control temperature is about 12 ć. By controlling the refrigerant valve, the temperature of the fermentation tank is kept constant. Then, in the cooling stage, the temperature drops at the specified rate by controlling the refrigerant valve. The reaction temperature is gradually decreased at a rate of about 0.28 ć per hour, into the secondary fermentation stage. During the secondary fermentation period, the typical control temperature point is about 4.5 ć. Finally, it enters the beerstorage stage at a typical cooling speed of 0.12 ć per hour [5].