Wild yeasts are used as leavening agents to produce carbon dioxide by utilizing sugars in the flour and thereby ferment in order to raise the dough. Therefore, the present study was carried out to characterize wild yeast isolates recovered from fruits to assess their leavening potential of wheat dough under laboratory conditions. The yeast isolates were retrieved from fruits following standard methods. From a total of 88 yeast isolates, three of them were selected on the basis of not producing H2S and sugar fermentation abilities. Based on colonial, morphological and biochemical tests, the three isolates were identified as genus Saccharomyces. The optimum growth pH and temperature values for the three selected yeast isolates were recorded as 5 and 30oC, respectively and 30% (w/v) glucose and 5% (w/v) NaCl concentrations in yeast extract peptone dextrose medium. In all cases, the maximum biomass was achieved at 96 hrs of incubation but decreased rapidly afterward. Notably, of the three isolates, AAUGr5 was found to be potent for its leavening action. Generally, combined cultures of the three yeast isolate produced more CO2 and biomass and showed better leavening potential than their paired combinations or each isolate separately that clearly indicating the possibility of using the consortia of potent wild yeasts in the bakery industry.
Keywords: Saccharomyces, Biomass, Carbon Dioxide, Hydrogen Sulphide, Co-culture, Leavening potential