Induction of Freeze-sensitive Mutants from a Freeze-tolerant Yeast, Torulaspora delbrueckii.
Freeze-sensitive strains of yeast were induced from a freeze-tolerant yeast Torulaspora delbrueckii by incubation with ethyl-methane sulfonate as a mutagen. A maximum ratio of mutation was attained by the incubation at 30°C for 75min. One-hundred and fifty strains of freeze-sensitive yeast were selected by plating-culture for the first screening. The freeze-tolerance ratio of each strain was examined based on the fermentative activity before and after freezing in liquid medium and dough. Strain 60B3 showed the highest freeze-sensitivity in a pre-fermented frozen dough (pre-fermented at 30°C for 2h, and frozen at -20°C for 7 days) among eight strains finally selected.
a Department of Food Science and Nutrition , Nara Women's University , Nara 630 , Japan.
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Murakami
a Department of Food Science and Nutrition , Nara Women's University , Nara 630 , Japan.|b Department of Food Science and Nutrition , Sungshin Women's University , Seoul , Korea.
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Hahn
a Department of Food Science and Nutrition , Nara Women's University , Nara 630 , Japan.
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Yokoigawa
a Department of Food Science and Nutrition , Nara Women's University , Nara 630 , Japan.
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Endo
a Department of Food Science and Nutrition , Nara Women's University , Nara 630 , Japan.
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Kawai