| Project/Area Number |
02680063
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
家政学
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| Research Institution | Nara Women's University |
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Principal Investigator |
KAWAI Hiroyasu Nara Women's University, Department of Food Science and Nutrition, Professor, 家政学部, 教授 (80026525)
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| Co-Investigator(Kenkyū-buntansha) |
ENDO Kinji Nara Women's University, Department of Food Science and Nutrition, Professor, 家政学部, 教授 (20031643)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1991: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1990: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Freeze-tolerant yeast / Freeze-tolerance, mechanism of / Freeze-tolerance, factors of / Purothionin / Phospholipase / 冷凍耐性桟構 / 凍結障害 / 酵母の冷凍障害 / 酵母の冷凍耐性機構 |
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| Research Abstract |
Factors that influence the freeze-injury of yeast was investigated to clarify the mechanism of freeze-tolerance of yeast in frozen-dough system. It was found that the temperature and period for freeze-storage influenced markedly the viability of yeast cells in a liquid medium, which depended on the freeze-sensitivity of yeast strains.
The fermentative activity of freeze-sensitive strain after frozen-thawed with purothionin, ananti-yeast protein from wheat, was depressed with increasing amounts of the compound, while little effect was observed in freeze-tolerant strain. The amount of UV-absorbing materials leaking out from frozen-thawed cells reached a maxiniuni at PH 3-4 in both strains, and it increased by the concentration of purothionin depending on the freeze-sensitive strain than the freeze-tolerant strain. The result indicated that the lysis of yeast cells, probably their cell membranes, might occur by the freeze-thaw treatment in the presence of purothionin, depending on the freeze-sensitivity of yeast strains.
It was also found that the phospholipase activity of yeast cell membrane fraction from the freeze-sensitive strain was highly accelerated by addition of durothionin, while the enzyme activity of freeze-tolerant strain was not affected by purothionin. Therefore, the susceptibility to freeze-injury of yeast was assumed to depend on the activity of phospholipase that catalyzes the degradation of phospholipids in cell membranes of yeast. As the activation of phospholipase from the freeze-sensitive strain by purothionin was depressed by addition of phosphatidylserine or phosphatidylinositol, we concluded that the freeze-sensitivity of yeast was related to the composition of phospholipid in yeast cells.
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