Acid-reducing effect of brewing water

The high residual alkalinity of brewing water can affect many important biochemical changes in the process of beer production. For malt that is normally germinated and baked, the pH of the mash is about 5.8, and the pH of the wort is about 5.65; in general, the pH of the brewing water can be increased or decreased by 0.3 for every 10dH change in the residual alkalinity of the brewing water. , so the residual alkalinity will have a series of effects on the brewing process of beer.

1.The effect of pH on enzymes 

During saccharification, pH has a significant effect on the action of various enzymes. The high residual alkalinity of the water causes the pH of the mash to rise, which can reduce the activity of the enzymes. For α-amylase and some exopeptidases, in the lower pH range of 5.2~5.3, the lower the pH value of the mash, the better the enzyme effect; when the pH exceeds the optimum pH range of the "enzyme", the If α-amylase is inhibited, the saccharification time will be prolonged; if the activity of β-glucanase is reduced and the decomposition of β-glucan is unreasonable, the viscosity of wort will increase; if endopeptidase is affected, only the decomposition of A small amount of soluble nitrogen slows down the process of protein decomposition into amino acids; when the pH value is as high as 6.0~6.2, the activities of aminopeptidase and dipeptidase are almost inactivated, and phosphatase is also inhibited, and only a few inorganic Phosphoric acid is decomposed from organic matter, but this small amount of inorganic phosphoric acid will quickly react chemically with bicarbonate to form insoluble phosphate precipitation, which will significantly reduce the phosphate content in wort, thereby reducing the buffering capacity of wort.

2.The impact on the yield 

Due to the inhibition of the action of enzymes, the viscosity of the wort increases, the wort is difficult to filter, and the wort is not washed thoroughly, resulting in a 2-3% reduction in the yield of saccharification.

3. Influence on the properties of wort 

When the pH value of the mash, the number one wort and the washed lees is too high, many harmful substances in the husk that are unfavorable to the taste enter the wort, resulting in an increase in the color of the beer, and the taste is rough and jerky. Some proteins that are precipitated under acidic conditions are not well precipitated at higher pH values, and are likely to cause the beer to form a turbid and unstable state.

4. The effect on the utilization rate of hop bitterness 

Although the utilization rate of hop bitterness is higher when the pH value of the wort is higher, this will cause a large amount of humus salt with strong bitterness to be dissolved in the wort, which will make the beer produce a harsh and rough bitterness. Therefore, when the residual alkalinity of the brewing water is high, the amount of hops added should be appropriately reduced to ensure an appropriate bitterness content, but the bitterness quality (refreshing) of the beer is still poor.

5. The effect on fermentation 

Fermentation rates may vary due to changes in free amino acids in the wort. Wort with high viscosity contains a large amount of macromolecular nitrogen and viscous polysaccharides, which are adsorbed on the surface of yeast cells, which hinders the physiological metabolism of yeast and causes premature aggregation and sedimentation, causing problems with flavor components and reducing the fermentation degree of finished wine. and so on; in addition, the degreasing process of the beer is also affected, and the composition, foam performance and stability of the beer will be deteriorated.

6. The impact on raw materials 

Dark malts are more soluble than light malts and therefore have a lower pH. The acidic melanoidin in dark malt can offset the 10dH residual alkalinity in water. It is reasonable to use hard water to produce dark beer, not only can it produce a strong malt aroma, but also the dissolution of a large number of phenolic substances can form a strong overall characteristic. Of course, even with a low residual alkalinity in the brewing water, it is possible to produce dark beer with typical characteristics by using a batching method suitable for the water quality.