Microwave Mutagenesis Is Suitable For Alcohol Ester Than Beer Yeast Strains Breeding

Beer yeasts(Saccharomyces cerevisiae) were employed for test. The fermentation characteristics which affect the beer flavor of them were determined. Beer yeast CF-1 with better flocculation ability, medium fermentation degree, faster fermentation velocity and higher ratio of higher alcohols and esters as parent strain.After microwave treatment, lead different medium plates were used as screening plates, seven Saccharomyces cerevisiae strains with lower production of higher alcohols by fermentation were selected from original strain CF-1. The basic effected characteristics on fermentation of the mutation ones were determined, and the result shows that the one named MB-7 was best of all. Higher alcohols production of MB-7 was 87.15mg/L, esters production was 19.85 mg/L, the ratio of higher alcohols and esters was 4.39, which is much superior than original strain CF-1.The genetic substances of beer yeast CF-1 and MB-7 was analyzed with RAPD. The result of RAPD by random primer shows a different electrophoretic band. The protein analysis shows there was no significant difference between the two strains. Thus it can be seen that MB-7 is a new Saccharomyces cerevisiae strain with proper ratio of higher alcohols and esters producing.Comparing with CF-1, the result of beer fermentation by MB-7 indicated that in terms of beer flavor compounds, the concentration of fusel oil decreased obviously with the others changing a bit. As a result, we found mutation one named MB-7 was much better, viewing the situation as a whole, than CF-1 as the parent.