Effect Of Low Molecular Weight Compounds On Oxidation Stability Of Beer

Oxidation stability is a very important quality indicator of beer,which directly affects the shelf life and drinkability of beer.The oxidative stability of beer is mainly determined by endogenous antioxidant activity,while the endogenous antioxidant activity is mainly determined by endogenous antioxidative compounds.These antioxidative compounds undergo complex metabolic reactions during beer storage,while low molecular compounds are the most significant components that affect beer oxidation stability during beer storage and can objectively and indirectly reflect beer aging processes and mechanisms.This paper systematically studied the changes of antioxidant activity and antioxidative compound in various molecular weight fractions during the beer brewing process,and determined the antioxidant activity and antioxidant constituents of beer.Then,a method for the analysis of low-molecular-weight beer compounds based on metabolomics was established.The process of forced aging of beer and the influence mechanism of oxygen content on low-molecular-weight compounds of beer were revealed.The potential oxidation stability markers for beer were clarified to improve beer oxidation stability.The main research results are as follows:(1)The changes of the antioxidant activity and antioxidative compounds of various fractions(original sample,>3KDa fraction and <3KDa fraction)during beer brewing process were studied.The results showed that saccharification and boiling stages are the main stages of the formation of antioxidant activity and antioxidative compounds.And antioxidative compounds mainly accumulated in <3KDa fraction which showed strong antioxidant activity.(2)The metabolomics technique was used to analyze the change of beer low-molecular compounds during the forced aging process,and the mechanism of low-molecular-weight compounds on the oxidation stability of beer was revealed.The results showed that there was significant positive correlation between antioxidant activity and antioxidative compounds of low-molecular-weight compounds during forced aging(P<0.01).With the prolongation of the aging time,the antioxidant activity decreased significantly,and the beer oxidation stability is deteriorated.A total of 2,114 compounds were detected from forced-aged beers using a metabolomics method.16 of these metabolites were rapidly identified,and(N-[(2S,3R)-1,3-dihydroxyoctadecan-2-yl] formamide and xanthohumol were used as markers for the oxidative stability of beer during heat aging.(3)Metabolomics was used to reveal the effect of oxygen content on the oxidation stability of beer during storage.The results showed that the oxygen content had significant effect on the oxidative stability of beer during storage.With the increase of oxygen content,the content of antioxidant activity and antioxidative compounds of low-molecular components decreased significantly,and the composition and content of low-molecular-weight compounds also changed.A total of 1,972 compounds were detected from forced-aged beers using a metabolomics method.14 of these metabolites were rapidly identified,and xanthohumol and isohumulone were used as potential markers of beer oxidative stability.