Gut Health Function of Instant Dehydrated Rice Sticks Substituted with Resistant Starch Types 2 and 4

The purpose of this study was to analyze the effects of instant dehydrated rice sticks (IDRS) which were substituted with resistant starch (RS) types 2 and 4 whose gut health function targets gut microbiota. IDRS are a type of rice noodles that were developed by two formulations. The first formulation had substitution of rice flour with 20% RS type 2 and 0.15% carboxymethyl cellulose (CMC) (RSc-2), and the second formulation had 25% RS type 4 and 0.15% CMC (RSc-4). RSc-2 and RSc-4 were investigated for gut health function by human fecal fermentation in a pH-controlled batch culture. The results of gut microbiota enumeration by fluorescent in situ hybridization confirmed that significantly (P < 0.05) higher numbers of bifidobacteria were obtained with RSc-2 (10.06 +/- 0.09 log cells/mL) and RSc-4 (10.00 +/- 0.06 log cells/mL) compared to the control (100% rice flour formula) at 24 h fermentation. Additionally, the prebiotic indexes of RSc-2 and RSc-4 were 3.8 and 2.8 -fold higher than that of the control at 24 h fermentation. The short-chained fatty acids, acetic, propionic and butyric acid were analyzed by gas chromatography-flame ionization detector. The butyric acids were significantly (P < 0.05) higher with RSc-2 (43.56 +/- 0.01 mM) and RSc-4 (43.63 +/- 0.07 mM) compared to the control at 24 h. Thus, RSc-2 and RSc-4 showed butyrogenic, bifidogenic and prebiotic potential to support gut health and could aid in prevention of colon cancer.