Effects Of Different Proteases On Physico-chemical And Gelation Properties Of Yak Meat Patties

The effects of 5 proteases on the physicochemical properties and gel properties of yak meat were studied.The cooking loss,pH value,texture index,free amino acid content and gel elastic modulus of yak meat patties with different hydrolysis time of 5 enzymes were determined and analyzed.The research experiments and results are as follows:1.The effects of fig protease hydrolysis time on physicochemical properties and gel properties of yak meat were studied.The results showed that: with the extension of enzymatic hydrolysis time,the cooking loss rate of yak meat patties increased(P < 0.05),and the pH value declined significantly(P < 0.05).The content of free amino acids in Yak patties increased significantly(P < 0.05).After enzymatic treatment,the hardness,cohesiveness and adhesion of the patties decreased(P < 0.05)except for the springiness,and slightly increased at 150 min(P > 0.05).The storage modulus G' enlarged gradually with the increase of angular frequency,and decreased after reaching the peak value,indicating that the gel structure of the system was weakened.From the gel formation to the denaturation of gel structure,the control group had the highest G' and the best springness of the gel formation.2.The purpose of this study was to investigate the effects of papain on gelation properties,physic-chemical properties of yak meat patties.The results showed that cooking loss rate of yak meat patties after enzymatic hydrolysis was higher than that of samples without enzymatic hydrolysis,while the pH value was significantly lower than that of the samples without enzymatic hydrolysis(p<0.05),the content of free amino acids was significantly increased with the extension of enzymolysis time(p<0.05).After enzymolysis,the springiness,adhesiveness and gumminess of meat patties were decreased(p<0.05)except for hardness,but these measures were increased at 150 min.The G' and G'' increased with the increase of angular frequency,and G' and G'' decreased at the end,indicating the weakening of gel structure of the sample system.From the gel formation to the denaturation of gel structure,the G' and G'' of the sample was the highest at 150 min and the best elasticity of gel formation.3.The objective of this study was to investigate the effects of neutral protease on gelation properties,physic-chemical properties of yak meat patties.The results showed that: after treatment with neutral protease,the cooking loss rate of yak meat patties was not significantly declined(P>0.05),while significantly increased at 150 min,there was no significant change in pH value(P>0.05),Addition of neutral protease could significantly increase the content of free amino acids(P<0.05),and reached the highest value(300.80mg/100g)at 90 min.With the extension of the enzymatic hydrolysis time,the hardness and adhesiveness of yak meat patties decrease not significantly at 30 min of enzymatic hydrolysis,but decreased significantly after 60min(P<0.05).The springiness and gumminess of yak meat patties decreased to different degrees,but the changes were not significant(P>0.05).The G' and G'' increased with the increase of angular frequency,and G' and G'' decreased at the end,indicating the weakening of gel structure of the sample system.From the gel formation to the denaturation of gel structure,the samples at 0 min had the highest G' and G'' and the best elasticity of gel formation.4.The effects of trypsin on the physicochemical properties and gel properties of yak mince at different enzymatic hydrolysis times were studied.The results showed that there was no significant change in the pH value of yak meat after treatment with trypsin(p > 0.05),and the amino acid content was the highest after 30 min of enzymatic hydrolysis.At the angular frequency of 0.1~100 rad/s,the energy storage modulus G was successively from large to small,and the enzymatic hydrolysis time was 30 min> 60 min>0 min>150 min>120 min>90 min.From the beginning of gel formation to the time when the protein denaturation gel structure was destroyed with increasing temperature,the control group had the highest G' and the best gel elasticity,followed by enzymatic hydrolysis for 30 min.There was little difference in the gel elasticity of yak meat after enzymatic hydrolysis for 60,90 and 120 min,and the worst gel elasticity after enzymatic hydrolysis for 150 min.5.The effects of elastase on the physicochemical properties and gel properties of yak mince at different enzymatic hydrolysis times were studied.With the extension of the enzymatic hydrolysis time of elastase,the cooking loss rate of yak meat showed a trend of increasing first and then decreasing and then increasing.The cooking loss rate of yak meat was the smallest when it was not enzymatic,and the cooking loss rate of yak meat increased significantly after 60 min of enzymatic hydrolysis(p < 0.05).There was no significant change in pH value during enzymatic hydrolysis(p > 0.05).The content of free amino acids increased.With the increase of enzymatic hydrolysis time,the hardness and adhesion of yak meat increased,while the elasticity and cohesion decreased.The samples with enzymatic hydrolysis time of 0,90 and 120 min finally showed a decrease of G',and the change trend of G' was the same as that of G'.The angular frequency ranged from 0.1 to 100 rad/s,and G' was 0 min>,90 min>,150 min>,120 min>,60 min>,30 min.From the beginning of gel formation to the destruction of protein denaturation gel structure with increased temperature,the control group had the highest G' and the best gel elasticity,followed by the gel elasticity of yak meat after 60,90 and 150 min of enzymatic hydrolysis,and the three groups had little difference in the gel elasticity,and the worst gel elasticity after 30 min of enzymatic hydrolysis.The results suggested that fig,papain,neutral protease,trypsin and elastase all affected the physicochemical properties and gel properties of yak meat.The extent of the effects depended on the type of enzyme and the time of enzymatic action.