Abstract: 1,3-Dioleoyl-2-palmitoylglycerol (OPO), a nutritional fortifier, is usually supplemented into commercial infant formulas in the form of OPO-enriched plant-oil formula (namely OPO formula powder) to enhance the nutritional value of infant formulas. In order to demonstrate the nutritional function of OPO formula powder and to improve the applicability of OPO, anaerobic fermentation in vitro of OPO formula powder at different concentrations by the intestinal bacteria isolated from healthy college students’ feces was conducted in this study. Traditional culture techniques and gas chromatography (GC) were employed to study the changes in intestinal microbial counts as well as pH and short-chain fatty acids during 24 h of in vitro fermentation. Prebiotic index (PI) and Bifidobacterium/Enterobacter ratio (B/E) values were calculated. The results showed that supplementation of OPO formula powder promptly decreased the pH value compared with the blank control group, and the reduction was directly proportional to the concentration of OPO formula powder. Besides, it significantly increased the production of short-chain fatty acids, especially acetic acid and butyric acid. Furthermore, OPO formula powder could promote the growth of Bifidobacterium and Lactobacillus, but inhibit the growth of Enterobacteriaceae and Bacteroidetes, and increase PI and B/E ratio. The 50 g/kg of OPO supplemented group exhibited the highest PI at the end of the 24 h fermentation period. The increase in Bifidobacteria and B/E ratio were positively correlated with OPO concentrations during the first 12 h. Therefore, 50 g/kg of OPO supplemented is recommended for improved probiotic efficiency.

Key words: 1,3-dioleoyl-2-palmitoylglycerol, gut microbiota, fermentation in vitro, short-chain fatty acid, prebiotic index, OPO formula powder