Why does milk tea turn sour?

Because the shelf life of toluene in the air is longer than that of milk tea, it leads to cell division and bacterial reproduction, which leads to bad taste.

Supplement:

Milk tea, also called Mongolian tea, is an indispensable drink in the daily life of Mongolian herders. The tea used for milk tea is blue brick tea. Brick tea is rich in vitamin C, tannin, protein, acid, aromatic oil and other essential nutrients. Milk tea includes the most popular Hong Kong-style milk tea/desktop milk tea/silk stockings milk tea/Yuanyang milk tea, fruit juice, snow foam, iced black tea/green tea, foamed black tea/green tea, flavored tea, Kuledong and yogurt. Secondly, according to different seasons, milk tea can be divided into hot drinks and cold drinks, which are warm in winter and cool in summer. Judging from the current trend, there are more and more innovative types and more complete tastes of milk tea, which is loved by young people.