To identify the quality of beer, we can refer to the identification method of liquor and detect it from three aspects: color, aroma and taste. Only pure, transparent, pure taste, refreshing, mellow and mouth-watering beer is a good beer. 1. Look at the date. First look at the trademark of bottled beer. The back is generally printed with the factory date or date code "missing corner", that is, the production date. According to national regulations, the shelf life of bottled draft beer is 7 days; The shelf life of bottled cooked beer is 40-60 days. When beer expires, its quality will decline and it will not even be drinkable. 2. From the appearance, the high-quality beer liquid is clear and transparent, without suspended matter and sediment, and its color is light yellow, beige or golden yellow; Dark color, dull and suspended matter are defective products. 3. Look at this bubble. When beer is poured into a cup, there should be foam rising and continuing on the wall of the cup. The quality can be identified according to the foam condition. The foam color is white, delicate and creamy. On the contrary, the darker the color, the looser the foam. The higher the foam rises, the better the quality, and the longer the time from rising to disappearing, the better. It is better to last for more than 4-5 minutes. After drinking beer, the more foam remains on the inner wall and bottom of the cup, indicating that the beer quality is better; On the contrary, the foam is thick, yellow, short in duration and poor in quality. Take a sip of beer and taste its taste. If there is hops and malt fragrance, it is mellow, refreshing and soft, with a pure and comfortable aftertaste, and it is better to be stimulated by carbonated gas; If the aftertaste is astringent, it has the odor of yeast, glutinous rice and abnormal bitterness, and the quality is poor. 5. Smell the smell and inhale gently through your nose. Where there is obvious bouquet, pure malt aroma and ester aroma are the top grades, followed by original bouquet, aged aroma and bitter taste. If suspended matter, sediment and acid appear, it means that it has deteriorated and cannot be bought and eaten.