Production and Comparison of Indigenous and Commercial Baker’s Yeasts

Abstract

A comparative investigation on the characteristics, production and leavening action of two indigenous (isolate FR-1 and DP-4) and three commercial baker’s yeasts (Saccharomyces cerevisiae strain FT, FP-1 and FP-2) was carried out in laboratory scale. The indigenous baker’s yeasts, FR-1 and DP-4, were isolated from fermented rice and decomposed pineapple and they were presumptively identified as Saccharomyces cerevisiae and Saccharomyces species respectively. Among these five yeast isolates, FR-1, FT, FP-1 and FP-2 were found similar in morphological and cultural characteristics. The effect of physicochemical properties on the growth and production of cell mass was studied. The maximum cell mass was found after 36 h of incubation during growth in MYGP and MYMP media containing 1.5% glucose at 30°C and pH 5.0. The maximum cell mass was produced by DP-4, followed by FP-2, FR-1, FT and FP-1. The effect of different bread ingredients on leavening was also investigated and it was found that oil, butter, egg and milk influenced the leavening action by these yeasts. The pathogenicity test of FR-1 and DP-4 on animal models (rabbits) exhibited no abnormalities in the experimental animals. The indigenous isolates, FR-1 and DP-4, seemed potential as candidates for bread making.