Study On The Preparation Of Calcium Supplements From Channel Catfish And Its Properties

Channel catfish (Ictalurus punctaus) processing industries have been growingdrastically to accommodate international rapid changes in supply and consumerdemand for aquatic products. However, more and more inedible byproducts werediscarded after catfish processing. Thus, efficient recovery and use of suchbyproducts is very important to reduce environmental problems and to maximizeeconomic benefits. Calcium is essential for living organisms. True calciumdeficiency would lead osteoporosis or other related diseases. It has becomegenerally accepted that the chelated forms of metals with amino acids aredemonstrably better assimilated by plants, animals, and human beings than metalssupplied in inorganic forms or as organic salts.In the present study, an enzymatic treatment procedure was devised to recoverfish bone from the frames discarded from industrial processing of channel catfish(Ictalurus punctaus); collagen peptide and compound amino acid were produced ina valuable solution of soluble nitrogen compounds by enzymatic and acidtreatments; the combinations between peptides (compound amino acid) and calciumion were studied to figure out the mechanism and degree of calcium ion binding;The formation of chelate was confirmed by the UV-VIS and FT-IR spectra; furtherstudy on the bioactive functional properties of the chelate and other calciumsupplements were carried out to obtain the best calcium supplement.The enzymatic hydrolysis of channel catfish frames with the complex offlavourzyme and neutrase was studied. The effects of factors including hydrolysistime, solid-liquid ratio, quantity of enzyme, pH, temperature, the proportion offlavourzyme and neutrase were investigated. The optimal enzymatic hydrolysisconditions were determined as: hydrolysis temperature50℃, pH7.0, hydrolysistime5h, solid-liquid ratio1:2, quantity of enzyme2000U/g and proportion offlavourzyme and neutrase1:1, respectively. The degree of hydrolysis underoptimum conditions could reach28.87%.Collagen peptide from bone of catfish was prepared by compound-enzymestepwise hydrolysis of alcalase and flavourzyme. Single-factor and orthogonalexperiments showed the optimal hydrolytic conditions of alcalase were: material-liquid ratio (w/v)4:50, temperature45℃, enzyme/substrate4%, pH8andreaction time3h, respectively. The degree of hydrolysis under these conditionscould reach39.49%. The optimal stepwise hydrolysis conditions of flavourzymewere: temperature50℃, enzyme/substrate4%, pH7.5and reaction time3h. Underthe above conditions, the degree of hydrolysis was47.2%and the flavor ofhydrolysate was improved.The combination between collagen peptide and calcium ion was studied bymeasuring chelate rate. The optimal chelate conditions were determined as:temperature60℃, pH5.4, time1.5h and ratio of collagen peptide to calcium2:1(w/w), respectively. Under the optimized conditions, the chelate rate ofCa-collagen peptide could achieve to82.53％. The formation of Ca-collagenpeptide chelate was confirmed by the UV-VIS and FT-IR spectra. Thecharacterization of amino acid composition of the chelate is similar to typicalcollagen-like protein.Compound amino acid and calcium chloride were prepared by acid treatmentof fish bone for chelation. The effects of several factors including chelate time,weight ratio of compound amino acid to calcium and chelate pH were investigatedby using a quick and reliable detection method for chelate rate. The optimal chelateconditions were determined as: chelate temperature70℃, chelate time2.1h,weight ratio of compound amino acid to calcium2.57, chelate pH8.25. Under theoptimized conditions, the chelate rate was about85%. Amino acid composition ofcompound amino acid chelated calcium showed highly similar to general collagendue to high content of collagen in fish bone protein. FTIR experiments revealedthat upon binding calcium, the amide A, I, II wave number was displaced,indicating that amino nitrogen atoms and oxygen atoms on the carboxyl group wereinvolved in chelation. In the UV scan spectra, absorption peaks of compound aminoacid and compound amino acid chelated calcium were clearly shifted, whichindicated that compound amino acid had reacted with calcium.The results of the various elements in mice blood and the thighbone metrologyof different groups showed that compound amino acid chelated calcium andcollagen polypeptide chelated calcium were better in calcium supplement effect onrat than other groups.