Preparation and bioavailability of Chlorella pyrenoidosa protein hydrolysates-calcium chelate

Abstract

To improve the bioavailability of calcium, Chlorella pyrenoidosa protein (CPP) was hydrolyzed to prepare peptide calcium chelate, and its structure, in vitro antioxidant activity, bioavailability and cytotoxicity were studied. Four peptide fragment fractions (F1: Mw < 1 kDa, F2: 1 kDa < Mw < 3 kDa, F3: 3 kDa < Mw < 5 kDa, F4: Mw > 5 kDa) were obtained after alkaline protease hydrolyzed and ultrafiltration fractionated. F2 and F3 exhibited strong chelation ability with calcium ions, and the carboxyl and amino groups of the peptide fragments may be involved in the chelation. Compared with CPP enzymatic hydrolysates, peptide calcium chelate (F2Ca, F3Ca) has more compact structure and smoother surface. F2/ F3Ca can protect RAW 264.7 cells against H2O2-induced oxidative stress by increasing the activity of CAT and SOD. The bioavailability of F2/ F3Ca is respectively 58.83 % and 54.74 %, which are higher than that of CaCl2. These findings indicate that chlorella peptide calcium chelate is a calcium supplement with potential for development.