Study On Peptide Calcium Synthesis And Preparation Of Peptide From Red Sea Bream Bone With Meat By Enzymatic Hydrolysis

Fish bones contain a large deal of protein and calcium, but they are usually processed into low valuable products and even discarded as waste. In this work, the red sea bream bone with meat was used as material, and the technologies of bio-enzymatic hydrolysis, ultrasonic dissociation and microwave synthesis were applied to prepare peptide calcium synthsis. Furthermore the synthsis was evaluated by UV spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscope.Five kinds of enzymes were used to hydrolyze the fish bone with meat. As a result of comparison of the hydrolysis’degree and the flavor of hydrolysates, trypsin and flavorzyme were chosen as the suitable enzymes. Through the orthogonal experiment, the optimal conditions of stepwise hydrolysis were gotten as follows:substrate concentration at 5%, pH 6.0,800U/g of trypsin was added to hydrolyze in the first 4 hours, and the following hydrolysis lasted 4h by flavourzyme at the dosage of 3000U/g. The results analyzed by HPLC showed that the content of essential amino acids in the hydrolyzate was 148.12mg/100mL, and the total amount of 15 kinds of amino acids was 332.94mg/100mLThe ultra filtration was used to divide the hydrolysate into 4 components, and their antioxidant activities were investigated including the DPPH. scavenging activity, the-OH scavenging activity, O2-·scavenging activity, reducing power and anti-lipid peroxidation. The results indicated that the peptides with a molecular weight less than 3kDa had the highest antioxidant activity.Fish bone residue was dissociated by different methods, indicating that the hydrochloric acid and lactic acid had better effects, and ultrasound accelerated the dissociation evidently, making the dissociation rate of calcium increased by 16.5%. The best conditions were optimized by single-factor and orthogonal experiments. The optimal conditions for the calcium dissociation by ultrasound and lactic acid were as follows:temperature 30℃, lactic acid 3.0mol/L, time 80min, ultrasonic power 576W, liquid-solid ratio 7:1. The optimal conditions for the calcium dissociation by ultrasound and hydrochloric acid were as follows: temperature 40℃, hydrochloric acid 2.0mol/L, time 60min, ultrasonic power 504W, liquid-solid ratio 9:1.The peptides were synthesized with calcium under the condition of microwave. The experimental results showed that peptides with a molecular weight below 3kDa were easier to interact with calcium dissociated by hydrochloric acid and ultrasound. The results of single-factor and orthogonal experiments indicated that the optimal conditions were:the mass ratio of peptides to calcium 3:1, microwave power 300W, time 180s, the peptides solution concentration 50g/L.The synthsis was analyzed by UV spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscope and the results showed that the structure of peptide calcium synthsis was different from peptides.