Look at foam: foam is one of the criteria to judge the quality of beer. A glass of beer with fine and rich foam looks more beautiful and makes people want to drink it at first sight. Moreover, the rich foam on beer can delay the precipitation and diffusion of carbon dioxide gas in beer, so that beer can keep its mouth-killing power (carbonic acid gas has strong irritation to the mouth) and refreshing feeling. But before judging beer foam, make sure the glass is clean, and oil stains or dishwashing agent residues will destroy the formation of beer foam.
The criterion for judging the quality of beer is simple. The quality of beer foam should be judged from the foamability, foam shape, foam hanging cup color and durability. Foamability refers to whether beer can produce foam after being poured into the glass according to regulations and how much foam it has. Generally, the foam thickness of beer is two fingers wide to be rich. Foam form means that the foam should be delicate, while the rough foam will burst and disappear soon. After the foam is hung on the cup, the color is as white as snow or the surface is slightly beige, and the beer with dark yellow foam color is not a good product. The durability of foam refers to the length of time that foam stays in the cup. The disappearance rate of beer foam with good quality will not exceed 50% within 1 minute, and beer foam with poor quality will dissipate for a long time.
After seeing the color and smelling the fragrance, it is the taste. Beer is ultimately for drinking. Good beer has pure taste, obvious fragrance, refreshing and fresh, full and mellow, pleasant bitterness, stimulated by carbon dioxide gas, and no yeast or other peculiar smell. Inferior beer tastes bad, and has obvious peculiar smell and strange taste, such as rancid smell, sour taste, iron taste, bitter taste, too sweet or tasteless.