German beer is mainly divided into wheat beer, white beer (also called pale beer), dark beer and unfiltered beer. If divided according to brewing process, location and brewery, German beer can be further divided into the following categories:1.Pilsner beerPilsner is the youngest beer category in the

​Polyphenols in beer mainly come from barley and hops. About 80% of them come from barley and 20% from hops. The phenols in barley are about 0.1% ～ 0.3% of its dry weight, mainly distributed in wheat husk, aleurone layer and endosperm. With the dissolution of malt in the process of malting, it is free and brought into wort and beer through the saccharification process. Phenolic substances in hops account for 4%~10% of the dry matter, mainly distributed in the bracts and rachis of hops.

The pH value of mash is closely related to the action of phosphatase contained in malt and the residual alkalinity of brewing water.Inorganic phosphate is necessary for yeast metabolism and acidity buffering in wort, and it is almost entirely derived from organic phosphates in barley malt.