pH Value In The Beer Brewing Process

Acids in beer consist of two main categories, one is maltogenic acids, acids produced by biochemical and chemical reactions in saccharification and fermentation, mainly organic acids, and the other is acids added during saccharification. If these acids have a high content of strongly ionised acids and release a lot of H, the pH of the beer will be low. However, pH is logarithmically related to H concentration. Small changes in pH can lead to large changes in H concentration. At the same time, the H concentration is also influenced by the proportion of acid roots saturated by the salt base.

One. the role of pH in beer production

During the saccharification process, starch decomposition, protein decomposition, β-glucan decomposition and other reactions must be completed with the help of enzyme action. So the saccharification process is also a process of enzyme action. The pH value is an important determinant of enzyme activity. The role of pH value in the preparation of wort is expressed in several aspects:

(1) Shorten the saccharification time or optimise the saccharification method.

pH is one of the decisive factors for enzyme action, when the mash pH is adjusted to 5.5-5.6, α-amylase, β-amylase decompose starch faster and more thoroughly. It is conducive to increase the concentration of leachate, i.e., the yield of wort.

(2) appropriate pH is conducive to accelerate the wort filtration, accelerate the action of β-glucanase is conducive to the decomposition of glucan, the mash viscosity is lower, the content of fine protein colloid is less, accelerate the wort filtration. If the pH of the wash water is high, multiple enzymes and bitter substances are easily washed out, affecting the wort filtration, which in turn affects the composition of the wort and protein flocculation during boiling.

(3) low pH is conducive to protein coagulation, wort boiling, pH down 0.2 ~ 0.4. The lower the pH is close to the isoelectric point of protein, the more favourable to the protein coagulation precipitation. pH in the range of 5.2 ~ 5.6, the lower the pH, monolithic and anthocyanin is easy to act with the proteins and coagulation precipitation, precipitation.

~With high pH value, hop a acid dissolves well, but the bitter taste is coarse. The hop aroma is more refreshing. However, the low pH a-acid solubility decreases, the isomerisation rate is low, i.e. the hop utilisation rate is low.

(4) Strengthen the decomposition of nitrogenous compounds and colloidal substances, when the mash pH is adjusted to 5.4-5.6, the role of endopeptidase and carboxypeptidase is strengthened, the protein decomposition is complete, so that more proteolytic products are formed, permanent soluble nitrogen, and the free amino acid content is high.

(5)On the influence of colour, polyphenols and malt, hops in the phytochrome material leaching amount and pH value is closely related, lower pH, polyphenols and phytochrome material leaching amount is less, less Melad reaction products. The effect of flocculation and precipitation is stronger for monolithic anthocyanins and proteins.

(6)The decline of pH value during fermentation mainly occurs in the initiation stage, and logarithmic growth stage, i.e., 3~4 days before fermentation. pH value decreases very fast. In the post-fermentation phase, the rate of pH drop slows down significantly and remains almost constant to obtain an equilibrium. Suitable pH value can improve the fermentation degree of beer, yeast growth, improve the main fermentation and post-fermentation quickly.

(7) Promote the conversion of diacetyl precursor substances, so that the taste of beer is more delicate and pure, the yeast suspended in the beer, cold condensate and hop resin slowly precipitated, so that the beer is gradually clarified, the taste of beer is maturing.

Second, the PH value of the influence of beer flavour and smell

(1) Acetaldehyde, diacetyl, Hs coexist in the formation of young beer, raw green flavour to give the beer is not pure, uncoordinated taste and smell. When the content of acetaldehyde is too high, it gives people an unpleasant rough bitter taste; even a spicy rotten grass flavour. Experimental evidence: the higher the pH of the wort, the higher the acetaldehyde content of the finished wine.

(2) The total acid content of beer is low, the beer taste viscous, dull, not crisp. Total acid content of beer is high, the beer is rough, not coordinated, not soft. It will also affect the beer foaming and aroma characteristics.

(3) PH value has a greater impact on the content of aging substances in beer, thus affecting the stability of the taste of beer. pH value also affects the content of advanced alcohols, DMS and other fermentation by-products, thus affecting the flavour of beer.

In summary, there are many factors affecting pH in the beer production process. The control of these factors must be combined with cost, energy consumption, production cycle and efficiency. Beer flavour and quality and other aspects of comprehensive consideration, the development of scientific technology, pay more attention to the control of the production process pH, in order to achieve the desired results.