Preparation and in Vitro Digestibility of Pumpkin Peel Polysaccharide Chromium (III) Complex

In the study, pumpkin peel polysaccharide was extracted by hot water extraction, and a novel pumpkin peel polysaccharide chromium (III) PPP-Cr(III) complex was synthesized combined with trivalent chromium ions. Using the chelation rate as the evaluation index, the effects of the mass fraction between chromium and polysaccharide, reaction pH, reaction temperature and reaction time on the synthesis of PPP-Cr(III) complex were studied, the extraction conditions of PPP-Cr(III) complex was optimized by the response surface methodology, and the bioaccessibility of trivalent chromium ions in the PPP-Cr(III) complex was determined by in vitro simulated gastrointestinal digestion. The response surface analysis results showed that the optimum preparation conditions were as follows: The mass fraction between chromium and polysaccharide was 0.08:1, the reaction temperature was 60 ℃ and the reaction pH was 6.8, respectively, with the experimental chelation rate was 99.23%±0.12%. In addition, in vitro simulated gastrointestinal digestion studies showed that the solubility of PPP-Cr(III) complex in synthetic stomach conditions were stable and the dialysis rate of PPP-Cr(III) complex were higher than those of chromium chloride. Therefore, PPP-Cr(III) complex was a new potential type of chelate due to its high bioaccessibility of trivalent chromium ions.