ABSTRACT

The project work undertook a comparative study of palmwine yeast and commercial Baker’s yeast used for bakery production. Strains of Saccharomyces cerevisae were isolated separately from fresh raffia palmwine, 24hours raffia palmwine containing ‘‘NCHE’’ and oil palm wine respectively. Commercial Baker’s yeast was reactivated and cultured to determine the identity of the yeast content. All the yeasts isolates were used for bread baking after characterizing them accordingly. Results obtained show similar characteristics of all the yeasts but variations in their test performance including thermo-tolerance, ethanol, tolerance, osmo-tolerance, CO₂ production and baked bread quality. Baker’s yeast survived growth at 45^oC while the isolated yeast could not grow at temperatures above 37^oC. Two strains of the palmwine yeast and the baker’s yeast had ethanol tolerance unit up to 13% while one strain of palmwine yeast was limited to growth in 10% ethanol concentration. The yeast all grew moderately at 6% salt concentration, while the Baker’s yeast could not grow at 8% salt concentration. Two strains of palmwine yeast survived the growth while none tolerated 10% salt concentration. The baker’s yeast produced more CO₂ from glucose (1.47ml/min) than the palmwine yeast which produced 0.88ml to 1.15ml/min with the 18mins test time. All the yeast successfully leavened dough in bread production but with varying quality characteristics. Bread with palmwine yeast had a weight range of 210.67g to 219.00g as against 216.67g for the quality attributes. Also the baker’s yeast bread had higher volume (331.00cm³) than the palmwine yeast bread (251.33cm³ to 270.67cm³). There were no significant difference in the crude fibre and carbohydrate content of all the bread as well as the moisture content but the protein content, ash and fat contents were slightly but significantly higher in the baker’s yeast bread.