Comparison of Bread-Making Quality on Saccharomyces cerevisiae Strain YTPR1 Prepared in Different Conditions

The aim of study was to investigate bread-making quality on wild-type S. cerevisiae YTPR1 isolated from pear Red Bartlett fruits harvested in Yamagata, Japan, and was to compare its qualities on YTPR1 prepared in different conditions. Bread produced using frozen strain YTPR1 had a thin skin and crisp skin surface in crust, and had a moist and soft eat-feeling in crumb. Loaf was spread largely, but its bottom had relatively density. Loaf showed the same weight and volume, moisture, expansion ratio, specific volume, weight loss, and breaking force of crumb as that using commercially available dried yeast. In crust of loaf, L* value was higher but a* and b* values were lower than those of commercially available dried yeast. From results of brownness index, crust had a light brown color (golden brown color). In crumb, loaf was evaluated as appreciable in color difference. That is, loaf had an even baked color (desirable golden brown color). On the other hand, bread-making qualities on freeze-dried yeast, trehalose-addition yeast, glycerol-addition yeast, and L-glutamic acid-addition yeast were inferior to that on commercially available dried yeast. It concluded that high quality of bread with acceptable attributes could be produced using frozen yeast strain YTPR1 isolated from pear Red Bartlett fruits. However, these substances had not functions as cryoprotectant or cryosensitizer on yeast cells.