Fermentation characteristics of resistant starch from maize prepared by the enzymatic method in vitro.

To investigate the fermentation characteristics of resistant starch prepared by hydrolysing maize starch with α-amylase and pullulanase, fresh faecal extracts from healthy humans and infants were used as a fermentation model of human intestines in vitro. The RS was fermented for a certain period of time under the simulated condition of the large intestines (anaerobic and 37°C). The concentration of short-chain fatty acids in the fermented product as determined by gas chromatography was used as an index to characterise the fermentation effect. The results showed that the concentration of short-chain fatty acids, especially butyric acid, in the fermented product gradually increased with increased fermentation time and RS content. However, the concentration of short-chain fatty acids in the fermented product from healthy infant faecal extracts, especially butyric acid, was much higher than that from healthy adult faecal extracts. It suggested that the model of RS-produced acids was affected by the fermentation extract source, i.e., by the existence of microbial flora. The production model of acids demonstrated that maize RS prepared by the enzymatic method can be a promising ingredient of functional foods.