Screening for Fermentative Potency of Yeast Isolated from Some Fruits

It is obvious that yeasts play vital role in the production of wine due to their ability to convert carbohydrates such as glucose, maltose, sucrose, and fructose into alcohol and carbon (iv) oxide. Sourcing for yeasts that have excellent fermentative potential has been prioritized in Food and Industrial Microbiology. In this study, three fruits juices produced frommango, orange, and pineapple fruits were screened for the presence of yeast cells, and their fermentative potentials were ascertained. Ten different fruits comprising of ripped, over ripped, and spoilt mango, orange, and pineapple were purchased at Uli Market, Ihiala Local Government Area, Anambra State. Fruit juices were produced from the fruits by hand pressing and filtration. The presence of yeast in the fruit juices was evaluated by fermenting and culturing in Sabouraud Dextrose Agar. The yeast isolates were characterized based on cultural features, morphological characteristics, and biochemical characteristics.The ability of the yeast isolates to ferment carbohydrates was evaluatedby culturing in different sugar concentrations (1%, 2%, and 3%). The ability of the yeast isolates to tolerate different concentrations of ethanol was evaluated by growing them in 5%, 10%, and 15% ethanol concentrations. The ability of the yeast isolates to form flocs was evaluated using flocculation test in Yeast Peptone Glucose broth.The yeasts that had the highest occurrence wereSaccharomyces cerevisiae(4), followed by Pichia species (3) while the least was Rhodotorula speices (1).The yeast isolates fermented glucose, lactose, and sucrose and other sugars.The yeast isolates also showed the best growth at low ethanol concentration (5%) while all the yeast cells were inhibited at ethanol concentration of 15%.The yeast isolate that recorded the highest flocculation wasSaccharomyces cerevisiae which was isolated from mango and pineapple juices.Therefore, yeast cells isolated in this study have optimum fermentative potentials especially S. cerevisiae, which could be optimized in wine production.