Variation of wort in post-processing

During beer brewing, wort preparation is a complex process of physical and chemical changes. Wort preparation is a very critical process because of the success of beer brewing.

〖WORT OXYGEN〗

At high temperature, the polyphenols in the wort can easily react with oxygen, resulting in an increase in the color of the semi-finished wort and future beer; moreover, because of the oxidation reaction, the reducing substances in the wort will be reduced, and the antioxidant capacity will be reduced. Therefore, in the whole process of wort preparation, contact with oxygen (including the initial material) should be avoided as much as possible, and for this reason, hot wort should not be ventilated and contacted with oxygen before cooling.

At low temperature (below 40°C), oxygen is dissolved in wort mainly through physical action, and its dissolved amount is inversely proportional to the temperature and concentration of wort. For example, when the wort is at 85°C, the dissolved oxygen content is only 1/5~1/10 of that at 45°C; at 5°C, the saturated dissolved oxygen content of the wort at 14°P is 4.55mL/L, while at The dissolved oxygen content of P wort is 5.6mL/L.

The amount of dissolved oxygen in wort with the same concentration is related to factors such as wort temperature, wort movement state, and air pressure. Under the pressure of 0.1MPa, the saturated dissolved oxygen content of 12°P wort at different temperatures, see Table 1 below

Table 1

The total time from the hot wort entering the rotary sedimentation tank to the end of the wort cooling should not exceed 110 minutes or less at a high temperature of 90°C to 95°C. During this period of time, the increased chroma of the wort is relatively good within the allowable range of 1.0~1.5EBC. If the time is too long, the oxygen absorption of the wort will increase, and the color will be significantly deepened, which will not only affect the color and taste of the beer, but also And the stability of the finished beer will be poor. The color change of wort during post-processing, see Table 2 below

Table 2

〖BITTERNESS INCREASES〗

The bitter substances in wort are mainly reflected by the isomerization of α-acids. After the boiling, the wort needs to stand for 20~40min in the rotary sedimentation tank. At this time, the residual α-acid in the hop lees can still be leached by the hot wort, and the isohumulone content can be increased by 15%~25%.

〖WATER EVAPORATION〗

During the spinning and cooling process of wort, some water will evaporate, and its evaporation is related to equipment conditions, wort concentration, ventilation and external climate conditions. Due to the evaporation of water, the wort concentration increases accordingly. The amount of water evaporation using different cooling equipment is shown in Table 3.

Table 3

In order to make the wort to reach the concentration specified by the process after cooling, the water evaporation should be measured on the equipment in advance, and it should be considered that after the cooling is completed, the use of quantitative hot water in the top plate heat exchanger and the wort in the pipeline will cause the concentration. In order to avoid the phenomenon of high and low concentration of stereotyped wort, it will affect the stability of product quality or cause bad waste.

PHE Plate heat exchanger