Lipid content and cryotolerance of bakers' yeast in frozen doughs.
The relationship between lipid content and tolerance to freezing at -50 degrees C was studied in Saccharomyces cerevisiae grown under batch or fed-batch mode and various aeration and temperature conditions. A higher free-sterol-to-phospholipid ratio as well as higher free sterol and phospholipid contents correlated with the superior cryoresistance in dough or in water of the fed-batch-grown compared with the batch-grown cells. For both growth modes, the presence of excess dissolved oxygen in the culture medium greatly improved yeast cryoresistance and trehalose content (P. Gélinas, G. Fiset, A. LeDuy, and J. Goulet, Appl. Environ. Microbiol. 26:2453-2459, 1989) without significantly changing the lipid profile. Under the batch or fed-batch modes, no correlation was found between the cryotolerance of bakers' yeast and the total cellular lipid content, the total sterol content, the phospholipid unsaturation index, the phosphate or crude protein content, or the yeast cell morphology (volume and roundness).
Gélinas
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Lallemand Inc., Montréal, Quebec H1W 2N8; Département de Sciences et Technologie des Aliments, Université Laval, Sainte-Foy, Quebec G1K 7P4 ; and Food Research and Development Centre, Agriculture Canada, Saint-Hyacinthe, Quebec J2S 8E3, Canada.
Fiset
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G
Willemot
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C
Goulet
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