Synthesis and Characterization of Inulin Butyrate Ester, and Evaluation of Its Antioxidant Activity and In Vitro Effect on SCFA Production

The aim of this study is to develop a method for the synthesis of inulin butyrate ester (IBE) as a short chain fatty acid (SCFA) delivery carrier. Inulin is modified by butyric anhydride and the structure is characterized by Fourier Transform Infrared and 1H NMR. On this basis, the synthetic conditions are optimized with response surface methodology (RSM) to investigate the effects of three parameters (the ratio of anhydride to inulin, inulin concentration, and reaction temperature) on the degree of substitution (DS). Under the optimal conditions, the actual experimental DS is 2.59 ± 0.14. The antioxidant activities of inulin and IBE are determined by superoxide anion radical and hydroxyl radical scavenging ability. The results show that the butyrylation inulin increases antioxidant activities and indicate that IBE could be used as a potential antioxidant. In a 36 h in vitro fermentation experiment, IBE is shown to increase the total SCFA content and the butyrate ratio, which illustrates that IBE could be used as SCFA carrier for delivering high concentration of SCFA to the colon, and thus influencing intestinal health. This study presents the synthesis and characterization of inulin butyrate ester which can be used to increase the antioxidant activities of superoxide anion radicals and the amount of short chain fatty acid (SCFA). In vitro experiments show that it may enable delivery of high concentration of SCFA to the colon and may influence intestinal health.