Isolation and Characterization of Palm Wine Strains of Saccharomyces cerevisiae Potentially Useful as Bakery Yeasts

Abstract

A total of 12 yeast isolates from palm wine collected from various locations in Anyigba and its environs were selected for their leavening activities and were identified. The yeasts demonstrated high levels of leavening activities between 82-94. 7% as compared with commercial yeast (100%). Those that showed good leavening activities and were positive in assimilation tests for glucose, sucrose, maltose, galactose, lactose, raffinose and negative for lactose, xylose, lysine, nitrate and urea, were identified as Saccharomyces cerevisiae, while those that were positive in assimilating nitrate and lysine were identified as Candida spp. The yeasts were further assessed for attributes relevant to bakery operations such as production of CO2, temperature tolerance, ethanol tolerance, osmotic tolerance and flocculence. The rate of production of CO2 from different sugars ranges from 0.043 to 0.078 ml/min. The levels of CO2 produced by the palm yeasts in the presence of maltose were appreciably lower than that of the commercial yeast. The yeasts were able to grow at temperatures 30, 37°C and a few grew at 45°C though very sparely. Also, the yeast were tolerant to 8 and 10% ethanol but had very low tolerance to 13% ethanol. There was an appreciable tolerance to 6 and 8% NaCl but a few numbers sparingly at 10% NaCl. Some of the isolates demonstrated flocculation ability. In general, the studies indicate that Saccharomyces cerevisiae strains from palm wine samples from Kogi State have good properties for industrial usefulness in bakery operations.