Degradation of Phytate by High-Phytase Saccharomyces cerevisiae Strains during Simulated Gastrointestinal Digestion

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• 作者：Ann-Katrin Haraldsson ; Jenny Veide ; Thomas Andlid ; Marie Larsson Alminger ; and Ann-Sofie Sandberg
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2005
• 出版时间：June 29, 2005
• 年：2005
• 卷：53
• 期：13
• 页码：5438 - 5444
• 全文大小：117K
• 年卷期：v.53,no.13(June 29, 2005)
• ISSN：1520-5118

文摘

Hydrolysis of extracellular phytate (InsP₆) by high-phytase yeast strains and survival of yeast cellswere studied at simulated digestive conditions using yeast peptone dextrose growth medium andwheat gruel as model meals. An in vitro digestion method was modified to better correlate with thegastric pH gradient following food intake in vivo. High-phytase yeast gave a strong reduction of InsP₆(up to 60%) in the early gastric phase, as compared to no degradation by wild-type strains. Thedegree of InsP₆ degradation during digestion was influenced by the type of yeast strain, cell density,and InsP₆ concentration. Despite high InsP₆ solubility, high resistance against proteolysis by pepsin,and high cell survival, degradation in the late gastric and early intestinal phases was insignificant.Dependency on pH for phytase expression and/or activity seemed thus to be an important limitingfactor. Although further studies are needed, our results show the potential of using yeast as a phytasecarrier in the gastrointestinal tract.Keywords: Saccharomyces cerevisiae; yeast; phytase; phytate; InsP₆; solubility; in vitro digestion