Fermentation characteristics of yeasts isolated from apple and kiwi

Abstract

This study investigated the fermentation capacity of two natural yeast strains, Metschnikowia pulcherrima and Candida apicola, isolated from apples and fermented kiwi syrup, respectively. Natural yeasts are increasingly valued for imparting complexity, unique aroma, and distinctive flavor to alcoholic beverages and baked goods. However, their fermentation performance is often weaker and less stable than that of commercial dry yeast. To evaluate optimal conditions, each strain was cultured on agar and inoculated into liquid media containing yeast extract, peptone, and glucose. Bread dough was then fermented with each strain under varying temperatures, and sugar types and concentrations. Fermentation efficiency was assessed by measuring dough height. Statistical analysis was performed using t-tests and one-way ANOVA on triplicate data following Fisher’s three principles. Results showed that M. pulcherrima performed best at 25 °C with 5.0% glucose, while C. apicola showed optimal fermentation at 35 °C with 5.0% sucrose. These findings indicate that tailoring fermentation conditions to specific natural yeast strains can significantly enhance the efficiency of alcohol and bread production, offering a promising alternative to commercial yeast in both artisanal and industrial applications.