Characterization and antioxidant properties of Manchurian walnut meal hydrolysates after calcium chelation

A Manchurian walnut protein hydrolysates-calcium (MWPH-Ca) was prepared its characteristics and antioxidant activities after in vitro simulated gastrointestinal digestion were investigated. The optimal conditions for the chelation reaction were peptide to calcium ratio of 3:1, pH of 8, chelation time of 40 min, and chelation temperature of 45 degrees C, and the final chelation rate was 67.2%. The peptides were agglomerated after chelation, as the particle size increased. The FTIR results showed that the main sites of chelation are amino nitrogen atoms, carboxyl groups and the C=O of the peptide bond which has a negative dipole. The MWPH-Ca generally maintained good solubility in the gastrointestinal environment, which could improve the calcium absorption. In addition, the MWPH-Ca still retained antioxidant activity and was stronger than that of the MWPH after simulated digestion.