Improvement in corn flour applicability using lactic acid fermentation: A mechanistic study†

In order to enhance the applicability of corn flour using fermentation, Lactococcus lactis was isolated from pickle juice and was cultivated into a stable bacterial suspension with a bacterial concentration of 10(7)-10(8) cfu/mL and a pH of 4.00. Combination of: (i) a fermentation liquid obtained by dilution of this bacterial culture with pure water to a final concentration of 20%; (ii) a temperature of 37 degrees C; and (iii) a fermentation time of 4 days resulted in optimal fermentation of corn flour. The water-retention capacity of the fermented corn flour was approximately 75% of unfermented corn flour. Standardized corn dough was prepared using fermented and unfermented corn flour, and the viscidity and elasticity of the fermented corn dough were found to be approximately three times those of the unfermented corn dough. Both maximum tensile resistance and maximum tensile ratio of fermented corn dough were more than two times greater than unfermented corn dough. Analysis of the starch molecules in fermented and unfermented corn flour showed that the fermented corn starch particles were generally smaller and were irregularly shaped with many more water-permeable holes. The fermented corn starch had a lower molecular weight on average and a higher amount of amylose than unfermented corn starch and was partially hydrolyzed, with amylopectin as the major substrate. There was no noticeable difference between the fermented and unfermented corn starch regarding crystal structure, but the degree of crystallinity of the fermented corn starch was much lower than that of unfermented corn starch.