The formation and influence of acid in saccharification process

The pH value of mash is closely related to the action of phosphatase contained in malt and the residual alkalinity of brewing water.

Inorganic phosphate is necessary for yeast metabolism and acidity buffering in wort, and it is almost entirely derived from organic phosphates in barley malt.

At the beginning of saccharification, due to the decomposition of organic phosphates by phosphatase (also known as acidogenic enzyme, phytase) contained in malt, acid phosphates and buffer substances such as amino acids formed by protein decomposition are released, resulting in the titratable acidity of saccharified mash. The formation of mash increases the buffering capacity, thereby reducing the pH of the mash. The better the dissolution of the raw malt, the stronger its buffering capacity. Under relatively normal brewing water conditions, the pH value of the mash will naturally drop to about 5.8.

Since most of the active enzymes contained in malt have an optimum pH value of less than 5.8, it is necessary to adjust the acid (lactic acid, hydrochloric acid, phosphoric acid, etc.) or add lactic acid malt to make the mash pH at the beginning of mashing. The value is further reduced, which promotes the more favorable release and decomposition of organic phosphates and proteins, and forms more acidic phosphates and amino acids, etc. At this time, the titratable acidity of the mash increases, and the pH value is somewhat reduced due to the dissolution of a large amount of buffer substances. pick up.

Although the optimum conditions for phosphates are: pH 4.5~5.0 and temperature 50~53℃, low temperature (35~45℃) feeding is beneficial to the decomposition of organic phosphates to form acid phosphates and other comprehensive effects. On the contrary, high temperature feeding is not conducive to the decomposition of proteins and organic phosphates.

The increase of the phosphate content in the mash (or wort) can increase the acidity buffering effect of the mixed wort, and through its buffering effect, it can reduce the pH drop of the wort during boiling or fermentation.

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