Formation of Micella Containing Solubilized Sterols during Rehydration of Active Dry Yeasts Improves Their Fermenting Capacity

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• 作者：Virginie Soubeyrand ; Valeria Luparia ; Pascale Williams ; Thierry Doco ; Aude Vernhet ; Anne Ortiz-Julien ; and Jean-Michel Salmon
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2005
• 出版时间：October 5, 2005
• 年：2005
• 卷：53
• 期：20
• 页码：8025 - 8032
• 全文大小：171K
• 年卷期：v.53,no.20(October 5, 2005)
• ISSN：1520-5118

文摘

During their rehydration in aqueous media, active dry yeasts (ADY) may be supplemented with inactiveyeasts, yeast derivatives, or other optional complementary nutrients to improve their fermentationcapacity. We found that yeast sterols solubilized in situ during ADY rehydration were particularlyefficient for stimulating the fermenting capacity of ADY. Spontaneous solubilization of sterols duringrehydration occurred by the formation of micelles by membrane phospholipids and specific cell wallpolysaccharides and sterols, both compounds being provided by inactive dry yeasts (IDY). Thesemicelles contained a specific distribution of the initial sterols from the inactive yeasts. Above aconcentration of 100 mg L^-1 in the rehydration medium, these micelles acted as emulsifiers. Theircritical micellar concentration (cmc) was found to be about 4 g L^-1. During rehydration, purified micelles,at a concentration near the cmc, were able to interact quickly with yeast cell membranes by modifyingthe yeast plasma membrane order [monitored by steady-state fluorescence anisotropy of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene-p-toluenesulfonate (TMA-DPH) probe] and byincreasing the sterol contents of ADY. Such an enrichment of ADY by very low concentrations ofsolubilized sterols was very efficient for the completion of fermentations. This is useful when mustsare limited in available phytosterols or when micro-oxygenation is not desirable during fermentation.Keywords: Alcoholic fermentation; sterols; yeast; rehydration