Effects of different thickening agents on infant gut microbiota†
Infant microbiota has to progress from an almost sterile to a complex and varied community, so the main objective of this work was to evaluate the effect of three thickening ingredients on infant microbiota, as well as their in vitro gut fermentability. Experiments were performed using fresh faecal samples from healthy donors of 2–3 months of age. Stabilised stool samples were injected into Wheaton serum bottles containing pre-reduced MBM and 1% (w/v) fermentation substrates (locust bean gum, LBG; maize hydroxypropylated distarch phosphate, Mhdp; and pre-gelatinized rice starch, gRS). Samples were taken during fermentation, and pH, gas pressure, SCFA and bacterial population were analysed. The addition of thickeners resulted in a significant negative correlation (p < 0.05) between time and pH, showing significantly lower (p < 0.01) pH values for Mhdp and gRS than for LBG. Modified starches showed significantly higher values (p < 0.05) of total gas production than did LBG. Total SCFA molar concentrations for LBG, as well as propionate production, were significantly higher (p < 0.05) than for Mhdp and gRS. Regarding bacterial population, LBG promoted a more varied microbiota enhancing the growth of Atopobium and Bacteroidetes, whereas Mhdp and gRS induced higher Lactobacillus and Bifidobacteria at the beginning of fermentation. LBG induced moderate gas production and a slow drop of pH, and caused a decreasing acetate : propionate ratio, enhancing the development of a varied faecal microbiota. In contrast, Mhdp and gRS induced high gas production, a sudden drop of pH and a greater production of acetate, which promoted a less varied faecal microbiota.