Separation and Probiotic Effect of Fructose with Different Polymerization Degrees in Inulin

Inulin is a natural fructose polymer that can be used as a fat substitute in foods such as dairy products and bakery products and is often added to food products due to its effect on the regulation of intestinal flora (also known as the prebiotic effect). However, there are few studies exploring whether there are functional differences between fructose species with different degrees of polymerization (DP). Therefore, we focused on the separation of fructose species with different DP and their different effects on the balance of intestinal flora. First, the fractional precipitation method was used to separate short-chain inulin (DP:2-9), medium-chain inulin (DP:10-23), and long-chain inulin (DP:23 and above). Then, male C57BL/6 mice were randomly distributed into four groups and fed with a high-fat diet(HFD), a high-fat diet with added short-chain inulin(SCI), a high-fat diet with added medium-chain inulin(MCI), or a high-fat diet with added long-chain inulin(LCI) for two weeks. Finally, RT-PCR was used to detect the relative abundance of specific bacteria after this feeding course. The results showed that the abundance of common probiotics increased, and some harmful bacteria reduced after SCI, MCI, and HCI treatment. As the short-chain inulin has the strongest effect on improving the balance of intestinal flora, it may be a promising treatment option for patients with obesity, fatty liver, diabetes or other gastrointestinal issues.