Study On The Effect Of Polyphenol Substances On The Non-Biological Stabilities Of Beer

Polyphenol substances were not only one of the main factors in the non-biological stability of beer,but also important flavour substances in beer,which played an important role in the quality of beer. The change of polyphenol substances during the whole brewing process and factors which can influence the content of polyphenol substances in the wort and beer were investigated in this paper.The effect of polyphenol substances in worts and hops was compared in the article.The application of tannins in the saccharification process of beer was evaluated, combined with the mechanism of polyphenol and protein and the effect of polyphenol pellet on the quality and flavour stability of beer as exogenous antioxidants were researched.The polyphenol substances of malt was infused quickly during the protein rest in the mashing process; The TBA value of wort dropped constantly with the increasing of polyphenol content. The polyphenol content and TBA value of wort would be influenced by the malt raw material proporation,mashing temperature and time,mashing water pH, the temperature of sparging water and pH, wort boiling degree.The content of polyphenol substances and TBA value dropped constantly in fermentation process.Polyphenol substances oxidized and polymerized during storage as the participation of oxygen,which influenced the flavour stability of beer.Polyphenol substances in hops played a more significant role in improving the reducing activity of beer, compared with those in malts. The reducing activity of fresh and storage beer were improved,the content of carbonyl compounds and the aging degree of beer during storage were controlled effectively with the addition in boiling. The content of macromolecule proteins were considerably reduced with the addition of tannin acid in boiling and there was no significant change in other physical and chemical index of wort. The content of carbonyl compounds was considerably reduced and the antioxidant ability was improved greatly.The content of sensitive proteins dropped by 30% and there was no signifentant effect on sensitive polyphenol with 40mg/L tannin acid was added.The filtration rate and reducing activity of wort were improved when polyphenol pellet was added in brewing. It was proved that the beer final haze was decreased greatly and the colloid stability of beer could be increased in the forced test. It was found that the degradation rate of bitterness unite of beer was decreased greatly in the forced ageing test after polyphenol pellet was added in the mashing.