Effects Of Different Protease Treatment On Tenderness,Volatile Flavor Compounds And Ultrastructure Of Horse Meat

The semitendinosus of horse meat was used as the raw material, studied variation of the tenderness of horse meat during postmortem aging through injecting papain, bromelain and fungal proteast, then optimized the best condition of papain, bromelain and fungal protease to make horse meat tender. Finally studied the effect of different proteast on volatile flavor material and the ultrastructure of the horse meat.The results were as follows:1.The pH value increased signicantly during postmortem aging, and the pH value rised faster with injecting more papain, bromelain and fungal protease. The color of the horse meat became worse during postmortem aging. The water retention properties including cooking loss and water holding capacity got worse. Low concentration of protease improved water retention properties of horse meat, or water retention properties would become worse. Papain, bromelain and fungal protease had significant influence on CSP, MFI and shear forse. CSP and MFI increased obviously with adding more protease, and the shear forse decreased significantly. During postmortem aging, the total collagen content increased during postmortem, while the insoluble collagen content decreased with protease treatment. During postmortem aging, many small molecule popeptide appeared in treatment group. Myosin light chain 2, 20 KDa, 32 KDa and 75 KDa appeared at first, then they diappeared in the group with high concentreation protease treatment, Desmin and Troponin I disappeared.2. Used the orthogonal test to get the best conditions of papain to tender horse meat. The results showed that: In the conditions of papain dose 15U/g, treatment temperature 50 ℃, pH 6.0, treatment time 1h; or papain dose 10U/g, treatment temperature 50 ℃, pH 6.0, processing time 1.5h, adding papain could achieve better tenderizing effect.3. Used the orthogonal test to get the best conditions of bromelain to tender horse meat. The results showed that: In the conditions of bromelain dose 12U/g, treatment temperature 60 ℃, treatment time 1h,pH 7.0; or bromelain dose 16U/g, treatment temperature 55 ℃, treatment time 1.5h, pH 7.0.4. Used response surface methodology to get the best conditions of fungal protease. The results showed that: fungal dose, treatment time and treatment temperature had significant effects on cooking loss, shear force and sensory evaluation; the best condition of tendering horse meat was fungal dose 20.63 U/g, treatment temperature 53.12℃, treatment time 98.88 mins, pH value 6.86.5. In the study of volatile flavor compounds, the relative content and species of alcohols and ketones decreased significantly, but the relative content and species of aldehydes volatile substances increased. The relative content and species of ester and hydrocarbon were stable. The muscle fiber, perimysium and endomysium were destroyed because of papain, bromelain and fungal protease treatment. More and more muscle fiber fragments appeared during postmortem aging.