Research On Component Analysis And Discrimination Inspection Method Of Cow' And Goat' Whey Protein Powder

Protein is one of the most important nutrients in cow and goat milk.The protein of milk is divided into casein and whey protein.Compared with casein,whey protein has many advantages such as high digestibility,high protein efficacy,and high utilization rate.Whey protein is one of the important materials on infant formula powder.Compared with the cow'whey protein powder,goat' whey protein powder has some advantages such as easier be digested and absorbed and has lower allergenic protein content.goat' whey protein powder is more and more popular in infant formula industry.At present,some companies are driven by interest and therefore they are ambiguous in the statement of cow' and goat' whey protein powder.In this study,the sensitivity and reliability of SDS-PAGE method and Native-PAGE method were compared in the analysis of components of bovine and goat whey protein,and the inspection method was optimized.Building the identification model and judgment method of bovine and goat whey protein blended powder based on optimized inspection method.Finally,the feasibility and validity of the method were confirmed by blind verification.The study provides technical support and reference method for screening the mixed bovine and goat whey protein powder in actual production.The main conclusions of the study were as follows:(1)fresh cow and goat milk,cow' and goat' desalination whey powder D90,and cow'and goat' concentrated whey protein powder WPC were as the experiment materials.The differences of bovine and goat whey protein components were clearly demonstrated via SDS-PAGE and Native-PAGE analysis.However,the optimized Native-PAGE method was more prominent in differential expression.Thus,the follow-up study was mainly based on Native-PAGE method.(2)Based on the optimized SDS-PAGE method,the components of cow and goat whey protein were compared and analyzed.The main differences were as follows:(1)The?-lactoglobulin(?-LG)in cow whey protein was more complex and richer than that of goat whey protein;(2)The content of ?-Lactalbumin(?-LA)of goat whey protein was greater than that of bovine whey protein;(3)The molecular mass of the immunoglobulin IgG-H of goat whey protein was smaller than that of the corresponding bovine source component.(3)Based on the optimized Native-PAGE method,the components of cow and goat wheyprotein were compared and analyzed.The main differences were as follows: the number of separated bands,the distribution position,and the chromaticity of band.Contrast with standard components,a wide band of goat whey protein was separated,and that was ?-LA and?-LG polymerizing into a larger oligomeric protein;And a separated band on the top of bovine whey protein was ?-LA and the two bands on the bottom was ?-LG.Therefore,the two lower ?-LG bands separated from the bovine whey protein can be used as a distinguishing feature for identifying bovine and goat whey protein.The separation gel concentration of the optimized Native-PAGE condition is 15%,12.5%,and 8%;the optimal loading is between 30 ?g~15 ?g;the pre-electrophoresis current of electrophoresis condition is 15 mA,the sample is transferred to the separation gel and transferred to 30 mA.The electrophoresis time is about 4 hours.(4)A method was established for the identification of bovine and goat whey blending powder which based on Native-PAGE.The cow' and goat' desalination whey powder and concentrated whey protein powder were blended in different proportions.A different concentration gradient blended model was constructed,and the detection limit of blended bovine whey powder in goat whey powder was 10%(m / m).With the increase of the ratio of cows' whey powder,the color of two ?-LG bands of bovine whey protein separated from the samples gradually becoming deeper,and the color of the wide band of goat whey protein separated from the samples gradually becoming lighter.The best parameters of this method are as follows : separation gel concentration is 12.5%;the pre-electrophoresis current of electrophoresis condition is 15 mA;the sample is transferred to the separation gel and transferred to 30 mA;the optimum range of blended samples of desalted whey powder and concentrated whey protein powder is 30 ?g~20 ?g and 20 ?g~12 ?g,respectively;Native-PAGE electrophoresis is performed at 0-4 ?.By judging whether samples had the characteristic bands,a blending phenomenon was realized.The approximate mixing ratio of the mixed samples was judged via comparing the results of the sample separation with the blended gradient model.(5)Blind validation test: Six kinds of cow and sheep whey powder mixed samples were prepared by other folk.Samples were subjected to blind detection.The results showed that the blended detection rate was 100%,and the error value of mixed proportion was lower than10%.The method based on Native-PAGE is feasible and effective to detect the blending cow'and goat' whey powder.