Changes in Autolysis Solution of Brewer's Yeasts and the Evaluation of Autolysis

Four brewer's yeasts with different autolysis performance were used to study their microscopic morphology by scanning electron microscopy(SEM) and changes in solution during autolysis in order to find out the optimal evaluating indicator of yeast autolysis.Results showed that α-amino nitrogen,formaldehyde nitrogen,each molecule of protein content,and free long-chain fatty acid content had certain variations during autolysis,but there was no obvious regularity.Meantime,single factor was not suitable for the evaluation of autolysis as a direct indicator.Nevertheless,(A260 /A280)/yeast mortality showed an obvious and consistent trend during autolysis.When the yeast autolysis degree increased,the value of(A260 /A280)/yeast mortality gradually decreased.This indicator had the advantages of comprehensive,high sensitive,and less time consuming,also the method was easy to operate.It could reflect different autolysis performance of different strains,as well as differences of the same strain at different stages of autolysis.So(A260 / A280)/yeast mortality was a good indicator to evaluate yeast autolysis.