Breeding of Freeze-tolerant Yeast and the Mechanisms of Stress-tolerance
Abstract
Frozen dough method have been adopted in the baking industry to reduce labor and to produce fresh breads in stores. New freeze-tolerant yeasts for frozen dough preparations were isolated from banana peel and identified. To obtain strains that have fermentative ability even after several months of frozen storage in fermented dough, we attempted to breed new freeze-tolerantstrain. The hybrid between S.cerevisiae, which is a isolated freeze-tolerant strain, and a strain isolated from bakers' yeast with sexual conjugation gave a good quality bread made from frozen dough method. Freeze-tolerant strains showed higher surviving and trehalose accumulating abilities than freeze-sensitive strains. The freeze tolerance of the yeasts was associated with the basal amount of intracellular trehalose after rapid degradation at the onset of the prefermentation period. The complicated metabolic pathway and the regulation system of trehalose in yeast cells are introduced. The trehalose synthesis may act as a metabolic buffer system which contribute to maintain the intracellular inorganic phosphate and as a feedback regulation system in the glycolysis. However, it is not known enough how the trehalose protects yeast cells from stress.
- Publication:
-
Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers
- Pub Date:
- 2011
- Bibcode:
- 2011TRACE..11..247H
- Keywords:
-
- Bakers' yeast;
- Frozen dough;
- Freeze-tolerance;
- Stress-tolerance;
- Trehalose;
- Surviving ratio