Synthesis and characterization of calcium phosphorylated inulin complex as a new source of enriched calcium supplement with prebiotic effect in food

Abstract

Bioavailability of calcium in food is not high. Calcium ions can react with the organic acids such as oxalic acid and phytic acid in the food to form insoluble salt. Calcium phosphorylated inulin (CaPInu) was developed as a new potential functional food. Inulin was chemically modified by importing charged group using esterification with phosphate mixture in order to chelate calcium. Two equivalence points of the introduced phosphate groups were estimated to be around 3.85 and 8.76 by potentiometric titration. The structural characterization indicated that C₆-OH in the chemical structure of phosphorylated inulin was located in the outside of the sugar ring and its steric hindrance was relatively small and esterification was performed with phosphate easily. CaPInu could stimulate the growth of Bifidobacteria and decrase pH in vitro fermentation. Low pH in colon is benefit to the dissolution of calcium. Mice fed CaPInu diet had a higher serum calcium and femur weight compared with the control diet.

Keywords:
calcium phosphorylated inulin; degree of substitution; chelate; Bifidobacteria; colon