Study On Fermentation Technology And Flavor Substances Of Strong Ale Beer

In this thesis,SafAle HA-18,Lallemand Saison and SafAle BE-134 were selected from six kinds of strong ale beer yeast,including SafAle BE-256,Lallamand Nottingham,Joyferm JFA1340,Mangrove Jack’s M41,SafAle BE-134,SafAle HA-18,and Lallemand Saison,for comparative brewing experiments.Through testing the physical and chemical indicators,flavor substances and antioxidant capacity of three finished strong Ale beer the comprehensive performance of them was evaluated by comprehensive sensory evaluation,and a yeast suitable for the brewing of Ayer beer with high alcohol content was selected..The results showed that the fermentation performance of the three kinds of yeast was different..HA-18 was the best among the three in terms of sugar lowering speed,yeast sedimentation,tolerance to alcohol,and ability to produce alcohol.The other performances were moderate and there are no obvious shortcomings;Saison was the best among the three in terms of reproductive ability and reduction speed of diacetyl.The fermentation speed was also relatively close to HA-18.But the sedimentation of its was poor;BE-134 had better yeast sedimentation,but the overall fermentation performance was average,and the sensory quality of the finished beerwas poor.GC-MS was used to analyze the flavor substances of the three finished strong Ale beers.HA-18,Saison and BE-134 yeast produced a strong ale with a high content of higher alcohols.The alcohol-ester ratios（the ratio of total alcohols to total esters except ethanol）were 3.52（HA-18）,4.26（Saison）and 5.12（BE-134）,respectively.Among them,the HA-18 and Saison yeast brewed strong Ales had a balanced and coordinated flavor.There was no obvious upper head feeling after drinking.The alcohol-to-ester ratio of the strong Ale brewed with BE-134 yeast was the highest among the three.It will cause the drinker to have an unpleasant sense of upper head.Combined with the contents of ethyl acetate and isoamyl acetate in the finished beer,HA-18 yeast had the most outstanding ability to produce ester.The true fermentation degree of HA-18 was70%,which was higher than that of Saison（68%）and BE-134（67%）.Due to the weak sedimentation of Saison,the turbidity of the wine sample was significantly higher than the other two.The evaluation found that the sensory quality of the finished beer fermented by HA-18 was the best among the three types of beer.The three kinds of strong Ale beer meet the national standards.The antioxidant properties of beer were studied by detecting the TBA value and DPPH free radical scavenging rate at each stage of the three beer brewing processes.Three strong Ale beer wine samples were treated for 6 days and tested respectively..Analysis and test results found that:With the deepening of aging,the antioxidant activity of the three kinds of wine decreased gradually,especially in the early aging period.The antioxidant activity of HA-18 was significantly better than that of the other two,and the antioxidant activity of Saison and BE-134 was similar..In conclusion,HA-18 was the most suitable yeast for brewing strong ale beer.On the basis of determining the selection of yeast,the effects of fermentation temperature,the amount of sugar in fermentation broth,the amount of dry hops on the alcohol content and sensory quality of the strong Ale beer were investigated.On the basis of single factor experiment,the brewing conditions of strong Ale beer were optimized by establishing response surface model.The optimal process parameters obtained by analysis:fermentation temperature 20.44℃,15°P wort as the base,adding white sugar to increase the sugar content of the fermentation broth by 17.71°P,the fermentation broth with the sugar content of 32.71°P,dry injection of William Mate hops 0.41 g·L^-1.Under the optimized process conditions,the average sensory score for brewing strong Ayre beer is 91.33 points,the original wort concentration is 32.76°P,the alcohol content is 16.85%vol,and the true fermentation degree reaches 69.10%.The physical and chemical indexes and hygienic indexes of this strong Al beer meet the national standards.The appearance of this finished strong ale is light brown yellow,clear and transparent.The foam is white and delicate,and the wall-hanging time is long-lasting.The smells of hops,esters,malt and alcohol are coordinated with each other.The aroma is outstanding and the Ales are rich.The taste of the wine is full-bodied,with strong alcohol stimulation and strong lethality.