Selection And Application Of Low-alcohol Beer Yeast

Higher alcohols is the main flavor substance in the beer, adequate higher alcohols can give beer the full taste and coordination body,the beer will have different and miscellaneous flavor if higher alcohols content is excess and make people headache and vertigo and cause some human diseases. Reducing the content of higher alcohols in beer is one of main objectives that the modern beer enterprise pursued.The main method of control higher alcohols are strain improvement and conditions of fermentation, Quietly elegant, light fragrance, low content of higher alcohols, green and healthy of beer will be the development direction of 21st century'.According to the relation that between constructive metabolism of higher alcohols and lactic acid metabolic pathway,the good strain was got by compound mutation of UV-DES with triplication screening of lactic acid, calcium carbonate and TTC upper stratum medium of the preserved strain. The fermentation conditions were optimized by using reponse surface analytical method and the optimization fermentation parameters were got.The pilot production of beer fermentation was made by using 1000L stainless steel fermentation equipment with refrigeration of whole jacket, C.I.P automatic cleaning system.The content of higher alcohols of the strains was reduced by 24.34% after compound mutation of UV-DES. The fermentation conditions were got by using reponse surface analytical method, the optimization fermentation parameters are: fermentation temperature 10.91℃, content of amino acids 172.83mg/L, inoculum size 3.44% and the content of higher alcohols is 70.8 mg/L.The whole content of higher alcohols of the pilot beer is 70.67mg/L and lower than the average value of higher alcohols content of the beer made in well-known domestic and overseas big enterprise. The pilot beer quality come up to advanced world standards. The fermentation parameters of pilot beer are:alcoholicity 4%,biacetyl 0.071mg/L,total ester 29.1mg/L,total aldehyde 18.51mg/L,total acid 3.15ml/L, all indexes meet the national standards,the beer is yellowish,clean and clear,lustrous,body soft and thick aroma and has obviously fragrance of hop and malt and typical refreshing bitter taste and stimulation power.