MSc.

The study on “Process standardization for the production of baker’s yeast from mango stones” was undertaken at the Department of Processing Technology, College of Horticulture. The main objectives were to optimize the culture conditions and growth supplements for baker’s yeast production and to explore the feasibility of enrichment of biscuits with single cell protein (SCP).
The physical composition of mango fruit and chemical constituents of mango pulp were evaluated. The contribution of pulp, peel and stone in mango ranged from 65.22- 73.69 percent, 8.32- 12.18 percent and 13.5- 21.94 percent respectively. The pulp adhered to mango stones recorded 78.8-80.1 per cent moisture, 2.8-3.52 per cent reducing sugar, 10.25 per cent non reducing sugar, 13.77-13.05 per cent total sugar, 9.3-15.80B TSS, 1.9- 3.5 pH, 16.94-21.01 mg/100g ascorbic acid and 0.26-0.37 percent acidity.
The effect of different surface sterilization methods viz. autoclaving, hot water immersion and steam blanching on surface decontamination of mango stones were studied. Autoclaving of the substrate at 1210C and 15psi for 30 minutes was found to be the best surface sterilization method.
Lyophilized baker’s yeast Saccharomyces cerevisiae MTCC 172 strain was used for the study. The secondary/working inoculum was standardized by inoculating this strain into YEPD broth. The culture conditions for SCP production using mango stone as substrate was standardized. Factors like TSS, pH, duration of fermentation, aeration affecting the cell biomass production from mango stones by Saccharomyces cerevisiae MTCC 172 were evaluated. The optimum conditions of the substrate for maximum yeast growth were TSS (300B), pH (4) and provision of aeration by keeping in a orbital shaker at 100 rpm for five days.
The effect of supplementation with carbon, nitrogen, phosphorus and inducers on yeast growth, wet biomass yield, dry biomass yield and protein content were determined by supplementing media with broken wheat, NH2SO4, KH2PO4 and Biotin. Significant variation was observed between treatments. Maximum yeast growth (49.00×107 cfu/g) was observed in media supplemented with ammonium sulphate (0.8%). Wet (13.67g/l) and dry (2.18g/l) biomass yield were found to be highest in media supplemented with ammonium sulphate. Highest content of protein (39.38%) was observed in media supplemented with ammonium sulphate (0.8%), broken wheat (20g) and combination of ammonium sulphate, KH2PO4 and biotin.
The possibility of protein enrichment of biscuits was evaluated by incorporating baker’s yeast in biscuits so as to raise the protein to 15 and 20 percent level. The enriched biscuits recorded protein content of 14.85(T1) and 19.14 (T2) percent whereas the biscuits made from refined wheat flour had 11.21 percent protein content. Highest scores for organoleptic properties of biscuits was obtained for T0 (biscuits made from refined wheat flour) followed by T1 (15% protein enriched biscuits).