Analysis Of Phenols In Light Lager Beer And Its Correlation With Quality

Phenolic compounds are important substances that affect the flavor and taste quality of beer,and at the same time,phenolic compounds are also one of the main substances affecting the appearance quality of beer.In order to study the change law of phenolic compounds in the beer brewing process and its influence on beer quality,this study took the phenolic compounds(including monomeric phenols,total polyphenols and total flavanols)in different varieties of barley,malt and hops as the research objects,and systematically analyzed the changes of different phenolic compounds in each process of beer brewing,studied the quality differences between phenolic compounds in different raw material varieties,and determined the sensitive polyphenols in beer.And formulated the corresponding regulatory measures,the main research results are as follows:(1)HPLC was used to detect the monophenols and total polyphenols in 10 kinds of imported barley,8 kinds of domestic barley and their corresponding malts.The results showed that the monomeric phenol and total polyphenol content of barley increased significantly after germination,and the monomeric phenols in barley and malt mainly existed in the binding state;the similarity of monomeric phenol fingerprints found that the similarity of domestic barley was between 0.911 and 0.937;the similarity of domestic malt was > 0.95,while the similarity of imported malt was between 0.892 and 0.967.The results of cluster analysis and principal component analysis are basically the same,that is,8 kinds of domestic barley and 1 kind of imported barley samples can be clustered into one class,and 8 kinds of domestic malt and 3 kinds of imported malt samples can be clustered into one class.Therefore,through the fingerprinting technology of barley and malt HPLC,it is possible to simply and effectively distinguish the differences in the quality of domestic and imported barley and malt.(2)HPLC was used to detect the monophenol and total polyphenol content in 7 kinds of aromatic hops and 2 kinds of bitter hops,and the results showed that the monophenol content of aromatic hops was significantly higher than that of bitter hops,which would vary depending on the origin and year of the variety.The results of the fingerprint similarity analysis of hop monomer phenol show that the similarity of hops of the same variety is the closest,and the similarity of hop varieties with closer planting distance is relatively close.The results of cluster analysis show that when the discriminant distance is <5,hops of the same variety and the nearest planting distance can be clustered into one category,and the results of principal component analysis are basically consistent with the results of cluster analysis.(3)Using ultraviolet detection and analysis technology,the tracking and detection results of phenolic compounds in the fermentation process of beer of 6 varieties of malt raw materials show that the content of phenolic compounds varies throughout the brewing process of malt of different barley varieties.Among them,the total polyphenol content remained basically stable,with a content of 135.78～189.29mg/L;the monomeric phenol content of malt of different barley varieties was relatively low;the detection results of polyphenols of different degrees of polymerization showed that polymers > polymers > oligomers were presented in the entire brewing process,but the changes of total polyphenols and total flavanols of different varieties of malt in the beer brewing process were different,and some varieties showed a trend of increasing content,while some showed a decreasing trend.(4)The detection results of sensitive polyphenols showed that the reaction rates of total polyphenols with different degrees of polymerization and protein were in the order of medium polymer > high polymer > oligomer,and the order of reaction rate with total flavanols in wine was oligomer.Therefore,it can be considered that the sensitive polyphenols in beer are mostly concentrated in the middle degree of polymerization and the low degree of polymerization.(5)Simulating the beer production and filtration process,three different adsorbents were used to adsorb the polyphenols in the wine body,and the results showed that the adsorption capacity of the phenolic compounds in the wine body was PVPP> silica gel > diatomaceous earth,of which the average adsorption rate of PVPP to the total polyphenols in the wine body was 30.2%,the average adsorption rate of the total flavanols in the wine body was 16%,the average adsorption force of the total polyphenols in the wine body was 21.3%,and the average adsorption force of the total flavanol in the wine body was 14.8%.The average adsorption rate of diatomaceous earth to the total polyphenols in the wine is 11.2%,and the average adsorption rate of the total flavanol is 8.9%,which shows that the medium polymerization polyphenols in the total polyphenol substances are unstable and are easily adsorbed and removed.Therefore,it is recommended to use the beer clarification treatment technology of diatomaceous earth + silicone+ PVPP,which can effectively improve the abiotic stability of pale lager beer.