Unpleasant bitterness of beer

I believe that many people love to drink beer because of its refreshing and comfortable bitter taste. This wonderful bitterness should be just right: soft and comfortable, with a feeling in the mouth, but also dissipating quickly, with no bitterness afterward. If you encounter a beer that is not delicate in the mouth, rough in bitterness, uncomfortable, and has obvious after-bitterness, it is recommended that brewers analyze the reasons from the aspects of raw materials or production technology. How do we maintain the pleasant bitterness of the beer and improve the quality of the beer?

 Raw materials 

1. The quality of hops is poor; or long-term storage leads to aging, the content of ɑ-acid decreases, and the β-acid is oxidized in large quantities, resulting in bad bitterness.

2. The quality of malt is poor, and the skin is thick and rough; or it is crushed too finely, and a large amount of polyphenols are leached from the wheat husk in the saccharification and lees washing process, and the tannins are oxidized and polymerized at a higher temperature, which makes the beer produce obvious bitterness and astringency. .

3. When the content of magnesium, iron, manganese ions, sulfate, carbonate, residual alkalinity and total hardness in brewing water is high, it will also lead to bad bitter taste of beer.

 The process 

1. Unpleasant bitterness and astringency formed during saccharification

(1) The filtration time of wort is long, and excessive tannins, anthocyanins and fatty acids enter the wort, which will increase the unpleasant bitterness of the wort;

(2) The filtered wort is cloudy and unclear, and the wort enters too much oxygen during cutting, stirring and pouring, and the polyphenols react with oxygen to increase the bitterness of the wort;

(3) If the washing time is too long and the temperature of the washing water is high, the wort will have a bitter taste;

(4) In order to reduce costs, use the previous batch of saccharification water as the next batch of saccharification feed water, because the washed dregs water is prone to contain various bitter substances such as tannins and phenols, which bring bitterness to the new wort. .

(5) The boiling strength of wort is not enough, and the content of coagulum increases, so that the flocculation of tannins and proteins in hops and husks is insufficient, which will increase the bitterness of wort;

2. Unpleasant bitterness and astringency formed during fermentation

Factors Affecting Bitter Substances During Fermentation

╘Yeast varieties

Powdered yeast is more evenly dispersed in the liquor and has a larger contact surface, so it absorbs more bitterness than cohesive yeast; different powdered yeast and cohesive yeast also have different adsorption amounts.

╘Yeast inoculum

During fermentation, the loss of bitter substances was not related to the yeast inoculum but to the yeast proliferation. The greater the proliferation, the greater the loss.

╘pH

During the fermentation process, the lower the pH value and fermentation temperature of the liquor, the more α-acids that have not been isomerized are precipitated; the effect of pH on iso-α-acids is relatively small.

╘Wort ventilation

The more dissolved oxygen contained in the wort, the more and more vigorously the yeast multiply, the more bitter substances adsorbed on the surface of the new yeast cells, and the more the loss of bitter substances; Properly lowering the oxygen content can reduce the amount of bitter substances. loss.

╘Fermentation temperature and pressure

Open high temperature fermentation leads to strong reproduction of yeast, forming more bubble caps and precipitation of more bitter substances; in closed low temperature fermentation tanks, fermented under the pressure of 40~200kPa, the loss of bitter substances is reduced.

╘Fermentation bubble cover

Under normal circumstances, 10%-11% of the bitter substances in the wort are precipitated with the fermentation cap. The content of bitter substances in the foam cap is mainly related to the degree of isomerization of α-acid, which is related to the pH value of wort. The lower the pH value of wort, the lower the degree of isomerization of α-acid. the more precipitation.

╘ Fermentation time

Intense fermentation at high temperature and short time is lower than slow fermentation at high temperature and long time, and the loss of bitter substances is relatively large.

╘Fermentation vessel

Using a conical fermenter, fermenting beer below can reduce the loss of bitter substances by 10%; fermentation above can reduce the loss of bitter substances by 20%.