The source of bitter aftertaste of beer

Bitter taste is one of the special properties that distinguish beer from other beverages.Normal bitterness generally disappear quickly, leaving no bitter, after drinking with a refreshing feeling.In the process of beer production, if the technological conditions are not perfect, the quality of raw materials are defective, poor process hygiene, the bitter taste of beer will become rough, bitter, after long. The source of bitter taste after beer and preventive measures to talk about some simple views in practical work.

1. Use inferior or stale hops

   After storage, the bitterness of hop was oxidized and polymerized, and the amount of hard resin increased gradually.Especially in the case of poor storage conditions, such as high moisture content, high ambient temperature, sunshine, packaging is not strict and other factors,will accelerate the oxidation polymerization of α - acids,Form γ and  γ’resins, γ’resin is one of the sources of post-beer bitterness.

2. Excessive or improper addition of hop

  The amount of hop should be added according to the taste requirements of consumers in different markets, but it should be no less than 0.6‰, otherwise it may bring adverse effects to the non-biological stability of beer.In addition, the addition method of hop in wort boiling is very important to consider the production of α-acid and avoid excessive oxidation of picric acid. In general, the degree of isomerization of α-acid was the highest 30 minutes before boiling, and the increase was still significantly increased after boiling, but the increase was gradually reduced, because after boiling for a long time, part of the α-acid was further converted to alpha-acid resin until hard resin, resulting in rough bitterness. If hop is added too early, the oxidized picric acid will increase with the prolongation of boiling time, which is unfavorable to the exquisite bitters of beer. Generally, the isomerization time of hop can be 55-60 minutes. Therefore, it is advisable to add most of the hops 55 to 60 minutes before cooking.

3. Use water with high acidity or high  pH

Alkaline water directly used in brewing beer is likely to dissolve more bitter resin and bring bad after-bitter taste to beer. It also causes the polyphenols in malt and hops to enter malt sweat in large quantities, making beer taste rough and bitter. Contain higher bicarbonate temporary hard water, not only affect the activity of the enzyme, but also make hops bitter become rough, bitter and astringency after generation. The application of edible phosphoric acid or lactic acid to adjust the saccharification pot water pH5.4 -- 5.6, paste pot water pH5.8 -- 6.2, and then feed, and adjust the wash water pH5.5 -- 6.0.

4.Gypsum was used to improve the quality of Mg2+ and K+ mashing water

  A certain amount of sulfate in water is one of the reasons for the rough and bitter taste of beer, especially the bitter taste brought by magnesium sulfate and potassium sulfate. When the water contains too high Mg2+, K+, adding gypsum will produce a lot of magnesium sulfate, potassium sulfate. This kind of water quality can replace gesso with calcium chloride, its reaction is similar with gesso, intermediary does not transform into sulfate, so side effect is lesser, make beer taste downy mellow. But the chloride content must be less than 60ppm, otherwise it will make the beer salty.

5.Polyphenols polymerization

  Glutaric acid and polyphenols in wheat husk will lead to different degrees of bitterness in beer, and the bitterness will become worse with the increase of degree of polymerization. Therefore, malt with large and thin granules should be selected as far as possible, and formaldehyde should be added in the saccharification process to adjust the pH value of mash saccharification, so as to reasonably control the washing tank and prevent the intake of oxygen, so as to reduce the dissolution and polymerization of polyphenols.

6. Yeast autolysis

  During fermentation, when the yeast cells are in a state of abnormal conditions or hunger, or caused by excessive cell membrane permeability after cell wall broken, yeast cells protease and released enzymes such as carbohydrates, decompose cell itself, such as protein and sugar, lead to yeast cells is destroyed, the dissolution of protoplasm, producing yeast autolysis phenomenon. Yeast autolysis produces bitter amino acids such as histidine, methionine, leucine, isoleucine, ornithine, etc. When the content is high, beer will bring unpleasant aftertaste. The key to prevent yeast autolysis is to ensure the reasonable composition of wort, to control the fermentation temperature, the temperature of cold storage and the pressure.

7. High content of high alcohol

  In higher alcohols, when isobutanol, pentanol, and isoamyl alcohol levels exceed their taste thresholds, beer is given an unpleasant bitter taste. Both tyrosol and colouring alcohol have strong unpleasant bitterness.

  To sum up, there are many factors contributing to the bitter taste of beer. In addition to the above reasons, wort boiling strength is not enough, too much wort washing, wort coagulation separation is not good, fermentation is not strong, bitter bubble cap separation is not complete or not separation, wild yeast and miscellaneous bacteria pollution, heavy metal content is too high, beer oxidation will bring varying degrees of post-bitter beer.