Structural conversion of pectin fractions during heat processing in relation to the ability of inhibiting lipid digestion: A case study of hawthorn pectin

Abstract

Abstract This study used hawthorn as object to investigate the relation of structural conversion of pectin fractions during heat processing to the ability of inhibiting lipid digestion. Pectin fractions including water-soluble pectin (WSP), chelator-soluble pectin (CSP), and Na2CO3-soluble pectin (NSP) were isolated from hawthorn tissue after heat processing with different time, as well as the dissolved pectin (DSP) in the heating aqueous phase. The structural features of pectin fractions were characterized by degree of methoxylation, neutral sugar composition, and molecular weight (MW) distribution. After 30-min heat processing, the amount of WSP increased from 78 to 111 mg/g dry basis, while those of CSP and NSP decreased, meanwhile certain amount of DSP (68 mg/g dry basis) was generated. During heat processing, a dynamic alteration of pectin fractions involving solubilization and depolymerization occurred. The solubilization mainly happened in CSP and NSP, inducing a shift from water-insoluble pectin to WSP. The depolymerization occurred in homogalacturonan region of WSP, resulting in a formation of DSP. With the increasing heat time, a more pronounced depolymerization appeared in DSP, which resulted in forming a large amount of pectic polysaccharide fragments with small MW. The WSP showed a good rheological behavior and an ability to inhibit lipid digestion, which was higher than those of DSP. The inhibition rate of WSP (0.1% (w/w)) on lipid digestion decreased from 48.5 % to 11.2 % after 30-min heat processing. The results can provide novel knowledge to better understand the relation between structure and function of pectin in heat processing.