Comparison of the effects of longer chain inulins with different degrees of polymerization on colonic fermentation in a mixed culture of Swine fecal bacteria.

The effects of inulin with three different degrees of polymerization (DP) on microbial dietary fiber fermentation were compared in an in vitro simulator of the porcine large bowel. The three inulin isolates had a DP of 15 (from chicory grown in Hokkaido, Japan), and 10 and 24 (from Orafti, Belgium), while cellulose was used as a control. The Lactobacillus level in the DP 10 group at 48 h and bifidobacteria levels in the DP 15 and DP 24 groups at 24 and 48 h were significantly higher than in the carbohydrate-free and cellulose groups. The SCFA concentrations in all the inulin groups were significantly higher than in the carbohydrate-free and cellulose groups at 24 and 48 h. Ammonia nitrogen concentrations in all the inulin groups were significantly lower than those in the carbohydrate-free and cellulose groups at 24 and 48 h. The three different inulin types were fermentable by gut microbiota as indicated by substantial increases in SCFA. In particular, inulin DP 15 exhibited a clear potential to be used as a prebiotic with significant increases in Lactobacillus and Bifidobacterium populations, and concomitantly propionate and butyrate productions than cellulose at the early incubation time. There was a negative correlation between SCFA and ammonia nitrogen concentrations. These results indicate DP 15 product has similar potential as a prebiotic to DP 10 or DP 24 product and showed substantial equivalence to DP 10 and DP 24 products.