1990 Volume 41 Issue 2 Pages 115-121
Freeze-tolerant yeasts were screened from natural sources and their characteristics for dough fermentative ability were studied. One-hundred and 44 strains of fermentable yeasts were isolated from various sources using Koji extract as a selection medium. Four strains of yeast, D2_4, E2, F6 and A2, which had relatively high freeze-tolerance and dough fermentative ability, were selected. Their freeze-tolerance rate ranged from 70 to 92%, which reflected the high fermentative ability of prefermented frozen doughs after storing at-30°C for several days. The D2-4 strain also showed the highest fermentative ability in the sweet doughs, but in sponge doughs, CO2 production in the later stage of fermentation tended to decrease due to the lack of maltose fermentation ability. The quality of bread from frozen dough with the D2-4 strain was superior to that prepared by Saccharomyces cerevisiae, which was used as a control strain.