| 4-vinylsyringol(4VS)is a kind of characteristic flavor substance with "smoke flavor" and "clove flavor".In the bottom-fermented beer,4VS is called "phenolic off-flavour",which is not liked by consumers.However,4VS is one of the most important flavor compounds in top-fermented beer,which is deeply loved by consumers.The formation of 4VS in beer is mainly from the decarboxylation reaction of sinapic acid in the raw material.This reaction can occur in the process of malting,mashing and boiling,these high-temperature produced through thermal decarboxylation;it can also occur in the fermentation process of wort,which is caused by enzymatic decarboxylation of top-fermenting yeast,4VS can bring unique phenolic aroma to top-fermented wheat beer.Therefore,the formation pathways of 4VS in the top-fermented wheat beer was confirmed and the influence of different process factors on the content of 4VS in top-fermented wheat beer was mainly studied in this subject.Five aspects including yeast species,malt proportion,mashing-in temperature,boiling time and fermentation temperature were researched in detail.Through the use of laboratory scale test and pilot scale experiment with a daily output of 1,000 L,and according to the results of single factor experiment was carried out orthogonal experiment.The brewed finished beer was further analyzed by physicochemical indicators of beer,using liquid chromatography and gas chromatography for flavor substance analysis,combined with sensory evaluation,and the best process scheme to improve the content of 4VS in the top-fermented wheat beer was finally obtained: the top-fermented beer yeast was CGBTC-1,the ratio of barley malt and wheat malt is60%:40%,the mashing-in temperature is 37?,the boiling time is 90 min and the fermentation temperature is 20°C.According to the final experimental results,it was found that the mashing-in temperature had a great influence on the content of 4VS in the top-fermented wheat beer. |
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