Colour Profile, Pasting and Sensory Properties of Processed Sweet Potato Flour

In this study, sweet potato was purchased and processed using different methods to obtain 4 different sweet potato flour samples. Sample A was unfermented sweet potato flour, sample B was fermented spontaneously, while sample C and D were produced by fermentation using indigenous starter cultures of lactic acid bacteria and yeast for 48 h and 72 h respectively. Colour profile, Pasting and Sensory evaluation was conducted. The whiteness (L* value) obtained in this study is within the range of value (87.29-89.52), Also, the redness value (a*) and yellowness value (b*) of the sweet potato flour samples also showed a significant difference (p<0.05). Sample a had a higher value when compared with samples B,C and D. Pasting properties such as peak viscosity, trough viscosity, breakdown viscosity, setback, pasting temperature were determined. It was noticed that fermentation process and increase in fermentation time significantly (p<0.05) decrease the peak viscosity in this research work and all samples had a higher cooled paste viscosity than their corresponding hot paste viscosity. Nevertheless, sensory evaluation was carried out using thet 9-point hedonic scale, samples A,B,C,D are significantly different (P < 0.05).

Bioethanol production from sweet potato (Ipomoea batatas L.) flour using co-culture of Trichoderma sp. and Saccharomyces cerevisiae in solid-state fermentation

The aim of this work was to study the optimiation of co-culturing of Trichoderma sp. and Saccharomyces cerevisiae (1:4 ratio) on sweet potato (Ipomoea batatas L.) flour (SPF) for the production of bio-ethanol in solid-state fermentation (SSF). Maximum ethanol (172 g/kg substrate) was produced in a medium containing 80% moisture, ammonium sulphate 0.2%, pH 5.0, inoculuted with 10% inoculum size and fermented at 30ºC for 72h. .Concomitant with highest ethanol concentration, maximum ethanol productivity (2.8 g/kg substrate/h), microbial biomass (23×10(8) CFU/ g substrate), ethanol yield (47 g/100g sugar consumed) and fermentation efficiency (72%) were also obtained under these conditions. Cell interaction was observed familiar between the viable cells of Trichoderma sp. and S. cerevisiae when co-cultured. Ethanol production ability by the co-culture was 65 % higher than the single culture of S. cerevisiae from un-saccharified SPF.