The Effect Of Hops On The Characteristic Flavor Of Beer

Hops provide characteristic aromas for beer.In this study,Magnum,Saaz,Cascade and Tsingdao flower were used as the research objects to make the bottom-fermented beer.Combined the physical indicators,chemical indicators and sensory evaluation,the evolution of different varieties of hops’ characteristic aromas during beer brewing and their influence on beer’s characteristic flavor was explored.The results were as follows:(1)Taking beer direct fermentation without hops as a control,four types of hops including Magnum,Saaz,Cascade,Tsingdao flower were added to the wort,and beer was brewed by the bottom-fermented method.The fermentation period was 20 days.The effect of hops on beer aroma was studied.The results showed that the seven characteristic flavoring substances of beer were linalool,geraniol,citronellol,nerolidol,geranyl acetate,citronellyl acetate and methyl geranate.The content of linalool showed a downward trend in the early stage of fermentation,and then the content remained substantially constant.The content of geraniol decreased at first and then increased,but the overall tendency was drops.The content of citronellol increased significantly at the begining and then remained constant.The content of nerolidol showed a gradual upward trend.On the contrary,the content of geranyl acetate,citronellyl acetate as well as methyl geranate showed an upward trend during fermentation.(2)The difference of characteristic substances,sensory and physical as well as chemical indexes of beer with different hop varieties was analyzed.It was found that mono-terpene alcohol flavors were not detected in the beer without hops.There were certain differences in the aroma components and contents of beer brewed with different hops.The linalool,geraniol,geranyl acetate,and citronellyl acetate in beer brewed with different varieties of hops were significantly different,but there was no significant difference in nerolidoli,methyl geranate,and citronellol.Besides,the bitterness value,pH and other physical and chemical indexes and sensory styles of finished beer were also slightly different.(3)Taking Magnum as the hops to make bottom-fermented beer,the effects of hop addition amount,addition method and main fermentation temperature on beer were studied.It was found that the degree of influence of various factors on beer quality was hop addition amount>hop addition method>main fermentation temperature.(4)The beer fermentation process was optimized by single factor and response surface test.The results showed that when the hop addition amount was 0.53 g/L,the addition method was mainly added at the beginning of fermentation,the main fermentation temperature was 12℃,the brewing process was the best and the beer quality was better.