Study On The Preparation And Properities Of Compound Peptone From Chicken By-products

Based on chicken slaughtering by-products(including chicken bones,chicken liver,etc.)as the main raw materials,meanwhile soybean meal as auxiliary material,the paper studied the preparation technology of two kinds of compound peptone,which using hydrolysis of free enzyme and co-immobilized enzyme,respectively.Mainly included degreasing process and extraction of mixed protein by ultrasonic-assisted alkali;selected and co-immobilized of proteases,the conditions were optimized by single factor combined with the quadratic general rotary unitized design;the functional characteristics and microbiological test were used to evaluate the peptone products.In further study of enzymolysis chicken by-product for peptone as microorganism culture provided theoretical and experimental basis and beneficial exploration.First of all,used n-hexane for chicken by-products degreasing.With residual fat and total protein content as the evaluation indexes,using single factor combined with response surface analysis to optimize the degreasing process.Finally obtained the optimum process parameters were: liquid-solid ratio 4:1(m L/g),degreasing temperature 50 ?,and degreasing time 9h.Under the condition,the residual fat content was 2.09%,and the total protein content was 45.67%.Secondly,used ultrasonic-assisted alkali to extract mixed protein of chicken by-products and soybean meal.With protein extraction yield as the evaluation index,using Plackett-Burman design and response surface analysis to determine significant factors and uphill directions.Obtained the optimum process parameters were: raw material dry weight ratio 4:1(g/g),CBSM size 80 mu,lye concentration of 0.70 g/100 ml,liquid-solid ratio 15:1(m L/g),ultrasonic power 365 W,at 42? for 2 h,repeated two times.After three parallel determinations,the protein extraction rate was 54.63%.Measured CBSM proteins isoelectric point(PI)was 4.0,which resulted a high protein content of 62.64%.Thirdly,with degree of hydrolysis and peptone yield as examining indexes,contrasted the enzymolysis effects of trypsin,papain and complex protease,neutral and alkaline protease.Choosed two proteases with similar hydrolysis condition which resulted better enzymolysis effects,for the preparation of peptone.The parameters of enzyme hydrolysis were optimized by means of quadratic general rotary unitized design,and the optimal level factors for double enzyme ratio was 1.3:1(g:g),at 54? and p H 8.2 for 3.4h.Under those conditions,the actual yield of peptone was 29.28%,and the free enzyme peptone was obtained.Then choosed chitosan and sodium alginate as the carriers,respectively using cross-adsorb-crossing and cross-embeddng cross-linking methods for the co-immobilized of trysin and alkaline protease.With the immobilized rate and recovery rate of immobilized enzyme activity as indexes,using the single factor and orthogonal test to determine the preferable effect was sodium alginate as the carrier of immobilized,then analyzed the nature of the immobilized enzyme;with protein extraction yield as the evaluation index,using quadratic general rotary unitized design to get the optimum process parameters were: the amount of immobilized enzyme was 10%,at 62? and p H9.5 for 2.5h.Under those conditions,the actual yield of peptone was 32.14%,and the co-immobilized enzyme peptone was obtained.Finally,evaulated the physicochemical properties of the two peptone products,and compared the effects with commercal peptone,the results showed that the two peptones achieved the quality standard,which could be made into microorganism culture media.Microbial growth experiments for E.coli O157 and Bacilus subtilis were processed with two homemade peptone mediums,and calculated the generation of different inoculation doses.The results showed the co-immobilized enzyme peptone media was beneficial for the growth of two kinds of bacteria;bacteriology tests,including hydrogen sulfide test,indole test and V-P test,results were accord with standard of microbiology experiments,the products were qualified and were rich of nutrition,which could replace the commercial peptone products.