Effect of Intercellular Trehalose Content on the freeze Tolerance of Baker's Yeast in Frozen Dough

Commercial active dry yeast(ADY)had been treated with several methods,results showed that the leavening power and freeze tolerance of yeast in frozen dough.Yeast treated with hyperosmotic media,glycerol and trehalose show higher leavening power than non-treated yeast after freezing.Yeast treated with trehalose had extremly strong freeze tolerance,the freeze tolerance arrives 80.7% after frozen for one month.To see if freeze tolerance is correlative with intercellular trehalose content,the trehalose content of yeast was tested with different treat methods,Results showed that freeze tolerance was not correlative with intercellular trehalose content when trehalose content＞12%.Multiple treatment improved the leavening power of yeast before freezing but no good after freezing,it was maybe the stability of cell membrane decrease after multiple treatment.