Abstract: This study compared the differences in the proximate nutritional quality, organic acid components and structural characteristics of South China 9 (SC9) cassava flour before and after fermentation by five strains. The results showed that fermentation by Saccharomyces cerevisiae significantly increased the protein content of cassava flour to 0.83 g/100 g (P < 0.05), which was 2.2 times higher than that of the control group. However, the cyanide content was significantly reduced by Schwanniomyces occidentalis Klöcker fermentation (P < 0.05), and the degradation rate was 91.82%. After fermentation by Bacillus subtilis, the total content of organic acids was the highest, 10.987 mg/g. In addition, the yield of crude polysaccharide was 1.59% and significantly higher than that of the control group (P < 0.05). The peak viscosity, trough viscosity and final viscosity of cassava flour fermented by B. subtilis were 5 397.5, 3 439.0 and 4 770.0 mPa·s, respectively, and significantly higher than those of the control group (P < 0.05), and the breakdown value was 1 958.5 mPa·s and significantly lower than that of the control group (P < 0.05). The analysis of structural characteristics showed that the size of cassava starch granules became more uniform and significantly smaller after fermentation. Collectively, these findings suggest that fermentation by B. subtilis is beneficial to improve the nutritional quality of cassava flour in terms of fat, organic acid and crude polysaccharide and its processing characteristics.

Key words: cassava flour; fermentation; physicochemical properties; organic acid; processing characteristics