Synthesis, Characterization of Inulin Propionate Ester, and Evaluation of its in Vitro Effect on SCFA Production

In this study, the authors developed a method for the synthesis of inulin propionate ester as dietary fiber carrier to increase the amounts of short chain fatty acids (SCFA). The propionylated inulin showed an appreciable effect for increasing SCFA compared with control inulin. The structure characteristics of inulin propionate ester are established based on FT‐IR, ¹H NMR, and ¹³C NMR spectra. Meanwhile, response surface methodology (RSM) is used to optimize the synthesis conditions and investigate the effect of three parameters on the degree of substitution (DS). The optimal conditions are as follows: the ratio of anhydride to inulin of 4.5:1, the concentration of 30%, the temperature of 40 °C. The results indicated that the ratio of anhydride to inulin and the concentration has a significant effect on DS. Under these conditions, the experimental DS was 2.86. In a 48 h in vitro fermentation experiment, the results of propionylated inulin had a good potential for enhancing propionate ratio compared to control inulin. This experiment provides a novel carrier molecule whereby SCFA is chemically bound by an ester bond to inulin which would be beneficial for delivering high concentration of SCFA and influencing intestinal health.