The pH value of brewing water is usually around 6.8-7.2. Since the acid-like substances inside the malt are dissolved out, the PH value is a little lower after feeding the milled malt. However, the present pH value cannot meet the requirements of protein resting and saccharification.
Malt is rich in various enzymes which have their own suitable pH range. It is not easy to meet the requirements of all the different enzymes, but it is possible to make the PH value of the syrup close to the requirements of the main enzymes, for example, the PH values of α-amylase, β-amylase, sodase, R-enzyme, etc. are required to be between 5.2 and 5.6, so the most suitable PH value of the syrup should be between 5.2 and 5.6 in practical production.
To adjust the PH value of wort, besides treating the brewing water and adding gypsum to the saccharification water, the common method is to add food grade lactic acid, phosphoric acid, hydrochloric acid, sulfuric acid or lactic acid malt to the brewing water to make the PH value reach the required range.
When wort enters the bottom of the pot, it starts to be heated and boiled. Generally speaking, the boiling time is calculated when the temperature of wort rises to 100 degrees Celsius, and a reasonable boiling time is about 70-90 minutes.
The whole boiling process can be divided into 3 stages: preheating, preliminary boiling and boiling.
In the preheating stage, the wort is cooled naturally during the water release process. If the wort is reheated at the end of the whole fermentation process, it will take a long time, so preheating has the function of insulation, or slow heating.
For the initial boiling, it should take no more than 30 minutes. The spray in the percolator is still in progress, so the amount of steam is not large and the initial boiling is a preparation for the next stage.
For boiling, the wort is at a sharp boil because the steam volume is the highest. The boil strength should ideally be around 8-12%. This will improve the utilization of the hops; allow the proteins to coagulate and then ensure that the wort is clear and bright. Otherwise it will cause some off flavors.