Effect And Optimization Of Compound Exogenous Protease On Beef Tenderizing

Meat quality is a term used to describe a range of attributes of meat.Consumer research suggests that tenderness is a very important element of eating quality and that variations in tenderness affect the decision to repurchase.Furthermore,how to improve tenderness and quality of the toughness meat in order to reduce cooking time is now becoming a hot topic.The present search was conducted to assess the proteolytic activity of three kinds of exogenous enzymes(papain,bromelain and ficin),and their combination(B+P,B+F,F+P,B+F+P),then to investigate the influence of the enzymatic activity of each enzymes separately and the enzymatic activity of each enzyme combined between them.Based on the first single factor experiments,the higher papain activity(HPA),tenderization time and tenderization temperature were selected as independent variables for a three-level Box-Behnken experimental design and the shear force was response value for the regression analysis.According to the statistical models,it showed that all independent variables had highly significant effects on shear force(P<0.01),and the optimal values were at the HPA:24.09 U/g,tenderization time 15.26 hours and tenderization temperature:12.48? which was determined with three-dimensional response surface diagrams and contour plots.Under this condition the observe shear force value was Y1:1.322 kg.f,exhibiting a good agreement with their predicted values,showing the good applicability and feasibility of response surface methodology(RSM)for improving beef toughness.Based on the second single factor experiments,the optimal activity of bromelain combined with papain(B+P),tenderization time and tenderization temperature were also chosen as independent variables for a three-level Box-Behnken experimental design and the shear force was the response value for the regression analysis.According to the statistical models,it was observed in all the samples significant decrease in shear force and hardness of beef sample by 90-99%,however it was unable to increased cohesiveness(P<0.05),and the optimal values were at the B+P:24.10 U/g,tenderization time 9.27 hours and tenderization temperature 8.45? which was determined with three-dimensional response surface diagrams and contour plots.Under this second condition the observed shear force value was Y2:1.304 kg.f,presenting a good accordance with their predicted values,showing the good applicability and availability of response surface methodology(RSM)for improving beef toughness.In order to obtain an optimal tenderizing effect of exogenous protease to increase the tenderness of adult beef,the higher papain specific activity(HPA:24.09 U/g,15.26h,12.48?)and the optimal activity of bromelain combined with papain(B+P:24.10 U/g,9.27h,8.45?)were selected and injected in the adult beef meat and placed in 8-12?.Finally,after 9-15h of the injection level treatment,the effects of all these factors on the texture characteristics(Warner Bratzler shear force:WBSF,Hardness),and physico-chemical properties(protein content,moisture content,fat content,pH,water-holding capacity,Ash content and the muscle microstructure)of beef were measured to evaluate its tenderizing process.Compared with control beef,treatments showed that all independent variables had highly significant effects on shear force and hardness for improving beef tenderness(P<0.01).The optimal value was at the higher activity of the combined bromelain with papain(B+P):24.10 U/g.the physico-chemicals properties and the textural processing characteristics of the injected beef meat were analyzed.However,the pH values were significantly decreased(P<0.05),the higher WHC was also observed and the moisture content was the largest increased in highest levels of(B+P)treated samples(P<0.05).The scanning electrons micrographs showed an increase of the myofibrillar gap,which explained that strong muscle fibres were broken and the cell membranes were severely degraded.Therefore,the exogenous proteolytic enzymes combination injection could be regarded as an effective tenderization agent for beef meat.