FUNCTIONAL PROPERTIES OF YEASTS ISOLATED FROM SOME NIGERIAN TRADITIONAL FERMENTED FOODS

摘要

Yeasts play important roles in confering some desirable qualities such as nutritional value in traditional fermented foods. This study was carried out to investigate the potentials of yeasts isolated from some Nigerian traditional fermented foods for functional characteristics such as growth at pH 2.5 and 2% bile salts concentration and ability to lower cholesterol in culture medium. A total of 40 yeast strains were isolated from burukutu, ogi and pito. They were characterized phenotypically. Fifteen strains were selected based on the ability to tolerate pH 2.5 and 2% bile salts and they were further identified using API 20C AUX (Biomerieux, France) to be Debaryomyces hansenii (5), Candida krusei (4), Candida glabrata (2), Candida colliculosa (1), Pichia anomala (1), Pichia farinosa (1) and Pichia membranefaciens (1). At pH 2.5, C. glabrata SA2 showed the highest increase in viable cells count after 24h (6.31 log10 cfu ml-1) while the most sensitive strain was P. membranefaciens BA2 (0.70 log10 cfu ml-1). P. membranefaciens BA2 survived in 2% bile salts than other yeast strains, with viable cell increase of 0.84 log10 cfu ml-1 after 24 h while the least tolerance was observed for D. hansenii OA1 with an increase in viable cells of 7.76 log10 cfu ml-1. C. krusei OB1 exhibited the greatest reduction of cholesterol of 91.34% while the least reduction of 24.28% was observed for D. hansenii OA1 after 48h incubation. The yeast strains in this study demonstrated functional attributes which can be employed as dietary adjuncts for the development of non-dairy beverages with hypocholesterolemic attributes.