Study On Preparation And Characters Of Calcium Fish Protein Peptide Chelate

In this paper, fish protein peptide was produced from silver carp bone by hydrolysis, and the performance of different hydrolysis methods were compared, and the effect of extraction process on the extraction rate of soluble calcium was investigated, and then the optium preparation parameters for fish protein peptide and soluble calcium were determined; the fish protein peptide and soluble calcium were used for preparing the calcium fish protein peptide chelate by wet chelating method; and the parameters of wet chelating reaction were optimized. The properties and structures of different chelate products, which were produced by gradient ethanol were analyzed. The results showed as follows:1. The hydrolysis methods of fish protein were compared and chosen. The fish body after fish flesh isolation from skeletons was hydrolyzed by three different methods, acid hydrolysis, alkali hydrolysis and enzymatic hydrolysis, and their nitrogen recovery and hydrolyzing degree of the hydrolysate were 63.60%, 71.34%, 55.22% and 49.68%, 57.25%, 29.48%, respectively. The molecular weight distribution of peptide chain of acid and alkali hydrolysates were more centralized when compared with that of enzymatic hydrolysate. The calcium was dissolved easily by acid hydrolysis, and the phosphorus was dissolved easily by alkali hydrolysis, however, the salinity of acid and alkali hydrolysates were higher than that of enzymatic hydrolysate. After enzymatic hydrolyzed, the calcium and phosphorus mainly remained in bone dreg, and the salinity of its hydrolysate was much lower. The colour ranking of three hydrolysates from the deepest one to the deeper one were acid hydrolysate, alkali hydrolysate, and enzymatic hydrolysate.2. The effects of types of protease and pretreatment of raw material on hydrolysis of fish protein were evaluated. Four kinds of proteases Papain, Alcalase, Protamex and Flavorzyme were used for fish protein hydrolysis. The results showed that the types of protease influenced nitrogen recovery and the hydrolyzing degree of the enzymatic hydrolysates significantly. The nitrogen recovery of Papain, Alcalase, Protamex and Flavorzyme hydrolysates were 58.55%, 53.51%, 51.09%, 49.05%, respectively, and their hydrolyzing degrees were 29.58%, 25.91%, 25.26%, 41.30%, respectively. The molecular weight distribution of hydrolysates produced by Protamex, Papain and Alcalase was similar, while the proportion of low molecules of the hydrolysate produced by Flavorzyme was higher than other three hydrolysates. The nitrogen recovery and hydrolyzing degree were reduced by freezing and high temperature treatment of raw material, which were helpful for the broken of raw material, resulting in more smaller particles after the hydrolysis. The degree of broken of raw material has no obvious influence on nitrogen recovery and hydrolyzing degree, but has significant influence on the particle size.3. The effect of the degree of the broken of bone and acid extracting condition on the calcium extracting rate were investigated. High temperature and pressure treatments led to the decreasing in the proportion of large particle and increasing in the proportion of medium particle. The more smaller of the bone powder, the more higher of the calcium extraction rate, which was also correlated with the concentration and amount of HC1, the temperature and time of extracting positively. The optimum extraction parameters were: the particle size of bone powder was less than 75μm, adding 10mL 1mol/L HC1 into 1 gram bone powder, extracted at 30°C for 30min. The calcium extraction rate was 91.79% under the optimum conditions.4. The calcium fish protein peptide chelate was prepared using the fish protein peptide and the soluble calcium extracted from fish bone by wet chelating method. The chelate ratio increased with the increasing in pH and coordination ratio of peptide and calcium, and the decreasing of temperature. The optimum conditions for chelate reaction were pH 9.0, peptide-calcium complex ratio 4:1, temperature lower than 50°C for 5～40min, and ethanol was added after the reaction. Under these conditions, the chelate ratio was 94.32%.5. The separation and structural determination of chelate were studied. The final products were precipitated by gradient concentration of ethanol, named CA, CB, CC, CD, CE, CF, respectively. The recoveries of CA, CD, CE, CF were higher, while CB and CC were lower. The results of qualitative determinations indicated that the chelate exsited in CA, CB and CC, but no chelate structure in CD, CE and CF. Based on Infrared Spectroscopy and peptide-calcium distribution studies, in CA, calcium was intensively combined with high molecular weight peptide, forming a 5-ring chelate structure; while in CB and CC, calcium was also combined with low molecular weight peptide or amino acid by carboxyl, besides forming a chelate structure, while there was no chelate structure in CD, CE and CF, it was probably because calcium was not combined with peptide through chemical bond, but existed in free state, and the products probably were mixture of high molecular weight peptide and free calcium.