Research On The Protein Denaturation Mechanism Of Penaeus Vanmamei Meat During Storage

Protein denaturation was the key and hot point of aquatic products processing and quality control field.Penaeus vannamei were used as raw material to investigate the effect of additives,temperature and moisture content on the storage stability of Penaeus vannamei meat,and discussed the mechanism of Penaeus vannamei meat quality changed during storage based on the water activity preservation theory and glass transition theory.Therefore we could provide theoretical and technical reference during its processing and storage.The dominating results and consequences of this paper were as follows:1.Penaeus vannamei meat with addition of 10% trehalose,10% inulin and 5%maltodextrin were stored at –18oC for up to 2 months.Ca²⁺-ATPase activity,salt solubility,reactive sulfhydryl content and surface hydrophobicity of myofibrillar protein were analysed every 15 days during frozen storage.The cryoprotective effect of 3 additives on Penaeus vannamei was interpreted based on glass transition theory,which will offer theoretical foundation for cryoprotective agent screening.The results showed that addition of trehalose,inulin and maltodextrin inhibited the decrease of Ca²⁺-ATPase activity,salt solubility,reactive sulfhydryl content and rising trend of surface hydrophobicity.The additives delayed the degree of protein denaturation during frozen storage of Penaeus vannamei and the sequence of cryoprotective effect from high to low was trehalose,inulin and maltodextrin.Cryoprotective effect of trehalose and inulin on Penaeus vannamei meat was not significant（P>0.05）,whereas these two additives showed better cryoprotective effect than maltodextrin treatment（p<0.01）.2.Penaeus vannamei meat（PV）and Penaeus vannamei meat with addition of 5%（w/w）maltodextrin（PV-MD）at 3 moisture content（namely 6.5%,18.0% and 76.5%）were stored at5 different temperatures（namely –78,–35,–18,5 and 25oC）.Ca²⁺-ATPase activity value of myofibril protein was determined in different time intervals under different storage conditions.This paper discussed the mechanisms of Ca²⁺-ATPase activity changes at different storage conditions and the effects of temperature,moisture content and MD on muscle protein denaturation.The results showed that Ca²⁺-ATPase activity value decreased with the temperature increasing and the temperature of the most serious degree of protein degeneration was 25 oC when Penaeus vannamei meat were stored at different temperatures;Ca²⁺-ATPase activity value decreased faster with the moisture content increasing,Penaeus vannamei meat of the most serious degree of protein degeneration was the fresh meat when the Penaeus vannamei meat were stored at different moisture content;Ca²⁺-ATPase activity value of PV-MD wasdecreased slowerly than PV for Penaeus vannamei meat with MD and without MD.These illustrated that temperature,moisture content and MD had impacts on denaturation of myofibrils protein and the higher the temperature and moisture content,the greater the myofibril protein denaturation.MD could inhibit the myofibril protein denaturation of Penaeus vannamei meat during the storage.3.We got chemical reaction rate constant k of Ca²⁺-ATPase activity value changed with temperature and time with chemical reaction kinetics model to fit Ca²⁺-ATPase activity value of different storage conditions.We discussed the mechanism of Penaeus vannamei meat quality changed during storage based on the water activity preservation theory and glass transition theory through the model fitting parameter k mapped with T-T_g（the difference of storage temperature and glass transition temperature）,X_w/X_b（the ratio of moisture content and monolayer moisture content）respectively.The results showed that the changes of Ca²⁺-ATPase activity value under different storage conditions followed the secondary chemical reaction kinetics model,namely t/1/10C（28）-kC.The chemical reaction rate constant k value increased with temperature and moisture content increasing,but k decreased with addition of MD.By analyzing the relationship between the reaction rate constant k and T-T_g with X_w/X_b,it illustrated that during frozen storage of Penaeus vannamei meat,protein denaturation rate and degree were mainly affected by glass transition theory.While protein denaturation rate and degree of Penaeus vannamei meat was influenced by both water activity preservation theory and glass transition theory when they were stored at5 oC and 25 oC.And with the addition of MD could improve the value of T_g and X_b to further increase the stability of Penaeus vannamei meat.