Effect of Microbial Fermentation on Nutritional and Safety Value of Cassava-Based Food

Abstract

Background: Cassava is a potential energy-rich food crops to make different food products in developing countries but limited by a shortage of protein content and the presence of toxic cyanogenic glycosides.Methods: Cassava-teff flour fermented with three pure starter cultures of Saccharomyces cerevisiae, Lactobacillus plantarum and Lactobacillus coryneformis. Two different inoculum levels (0.5 and 1.5 ml) were used. 300 g of cassava-teff flour were fermented with each of single starter cultures at 24 and 48 h. Results: The analysis of pH, crude protein and cyanide content indicates fermentation samples with Lactobacillus plantarum and Lactobacillus coryneformis for 48 h with 1.5 ml inoculums resulted in highest pH reduction. Similarly, highest reduction cyanide was recorded with 1.5 ml inoculums of Lactobacillus coryneformis and Lactobacillus plantarum, while the least cyanide reduction was recorded in fermentation samples of Saccharomyces cerevisiae at 24 h of 1 ml of inoculum level, but this value is higher when compared upon boiling (47.77 mg/kg). The highest levels of crude protein were observed fermentation samples with 1.5 ml inoculum of Saccharomyces cerevisiae for 48 h. Regarding palatability, the panelist preferred that fermentation sample with 1.5 ml inoculums of Lactobacillus plantarum and Lactobacillus coryneformis at 48 h having the best taste with the score of 4.90 ± 0.17 and 4.87 ± 0.23 respectively over the control, while sample fermented with Saccharomyces cerevisiae was preferred in terms of flavor, texture and overall acceptability with score of 4.87 ± 0.23, 4.73 ± 0.11 and 4.67 ± 0.12 respectively over the control. Conclusions: Therefore, microbial fermentation is a promising candidate for improving nutritional and safety value of cassava- based food and suggested as a choice of the processing method, as this method significantly reduced cyanide content, increased protein content and improved sensory properties of injera.