| Hazelnut is betulaceae hazel nut tree species and have the title of "the king of nuts". Hazelnut meals, being obtained after extracting oil from hazelnut, are used as feed. The backward of hazelnut protein research, to a certain extent, restricted the development of the hazelnut industry rapidly. Currently, the study of hazelnut peptide concentrated in hazelnut protein hydrolysis process optimization, and the metal chelating ability and bioavailability of the hazelnut peptide was rarely reported. Zinc is an essential trace element for animal. At present, the main agent zinc supplementation are inorganic zinc and organic zinc. Inorganic zinc has low bioavailability and organic zinc does not apply to patients with diabetes, anemia. The peptide chelates zinc can be absorbed by means of the characteristics and mechanisms of peptides and actively absorbed in an integrated form chelates through the small intestine, thereby promoting the absorption of zinc. The polypeptide and zinc chelate with both advantages, and it is an ideal agent for zinc supplementation. Accordingly, the study of polypeptide and zinc chelate will provide theoretical basis and technical support for improving the comprehensive utilization of the hazelnut protein resource and developing new natural zinc supplementationIn this experiment, cold pressed hazelnut meal as raw materials, hydrolysis conditions and purification of hazelnut chelating peptide were studied, the bioavailability of zinc from soybean was examined. The main results were as follows: 1. By single factor tests and response surface optimization hazelnut protein hydrolysis process, the hydrolysis degree of hydrolysis and chelating rate were studied. The results were as follows:(1) By selecting five kinds of commonly used in hydrolyzed vegetable protein proteases to hydrolyze hazelnut protein isolate, alkaline protease was the most appropriate and was selected.(2) By single factor tests and response surface hydrolysis determined the optimal results:hydrolysis time 130 min, the substrate concentration 4%, enzyme-to-substrate ratio 4500U/g, pH 8.0, temperature 55 ℃. Under the condition of DH was 19.37%.Validation test result was 19.50±0.12%, with the theoretical value.(3)By the correlation analysis, zinc chelating ability and degree of hydrolysis was positively correlated, the correlation coefficient was 0.775.2. With chelating rate and chelate yield as the index, by single factor tests and response surface to optimize chelation process. The results showed that the pH 9.0, peptide mass ratio of zinc 14:1, temperature 60℃, time 50 min, under the condition the chelating rate and chelate yield were 34.52±0.22% and 21.10 ±0.25%.3. By ultrafiltration, ion column chromatography and gel column chromatography to isolate and purify hazelnut peptide, and qualitative analyzed. Test results were as follows:(1) After ultrafiltration treatment, the chelating rate and chelate yield of 5-10kDa peptides were 47.89 ±0.27%,16.90±0.20% respectively. F1 and F2 were separated by ion exchange chromatography, and F3 and F4 were separated by Sephadex G-25 column chromatography. Chelating rate of F2 was 59.85±0.45% and was the highest.(2) By Na2S method and infrared spectroscopy showed, hazelnut peptide zinc chelateh and hazelnut peptide were different and it was a new kind of chelate.4. By gastrointestinal digestion of soybean the bioavailability of zinc was examined, and the stability was studied. The results were as follows:(1) In vitro gastrointestinal digestion experiment, the bioavailability of 5-10kDa hazelnut peptides and F2 composition were 17.39±0.20% and 21.35±0.48% respectively, were increased by 65.61% and 103.33% than that of control respectively. This indicated hazelnut peptides had the ability to promote zinc absorption in soybean.(2) By thermal stability and pH stability study showed that,5-10kDa peptide and F2 components had good heat resistance and acid stability. |
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