Abstract: Zinc is an essential trace element for human body.The lack of zinc can lead to immune dysfunction and slow growth.As a new zinc supplement, natural protein peptide-zinc chelates have great development potential because of their rich nutrition, high safety and easy absorption.Soybean is a high-quality protein resource, as well as a good material for preparing bioactive peptides.In order to develop safe and easily absorbable zinc-rich products and improve the utilization value of soybean protein, peptide-zinc chelate was prepared by enzymatic hydrolysis of soybean protein.Taking the zinc-chelating capacity as an index, the optimum preparation process of soybean peptide-zinc chelate was obtained by single factor experiment and orthogonal experiment.Scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize the structure.The bioavailability was evaluated by simulating gastrointestinal digestion in vitro.The results showed that the optimum conditions for preparation of soybean peptide by enzymatic hydrolysis were as follows: pH 8.0, enzymolysis temperature 45 ℃, trypsin dosage 6%(based on the quality of substrate), substrate mass fraction 5%, time 4 h.The optimum conditions for peptide chelating zinc were peptide-zinc mass ratio of 4∶1, temperature 60 ℃, pH 5.0 and time 60 min.Under these conditions, the chelation rate of zinc reached 82.22%.The surface of soybean peptide-zinc chelate was uniform and loose, the carboxyl oxygen and amino nitrogen atoms in the peptide chain were the important interaction sites between zinc and soybean peptide.The results of in vitro simulation of gastrointestinal digestion showed that the dissolution rates of soybean peptide-zinc chelates in stomach and intestinal tract were 92.85% and 54.34%, respectively, and the highest intestinal permeability was 51.02%, both of which were higher than those of inorganic zinc salts.The results indicate that soybean peptide zinc chelates performed better retention and absorption characteristics than inorganic zinc salt.The soybean peptide-zinc chelate prepared in this study can be used as a new zinc nutritional supplement, with good bioavailability and high development prospect.