Effect-mechanism Of Protein Oxidation On Water-holding Capacity Of Muscle

In the present paper, the effect-mechanism of protein oxidation on water holding capacity (WHC)of muscle was investigated, in order to provide basis for oxidation control. The Fe3+-Vc-H2O2oxidationsystem was carried out to study the effect of oxidation on WHC of myofibrillar protein (MP) gel;besides, the effect of protein oxidation on WHC of beef during thawing was also studied; based on theresults above, a fluctuated-low-temperature combined with high-relative-humidity thawing storage wasdeveloped, aiming to realize fresh-keeping thawing of frozen meat. The results were as follows:In the Fe3+-Vc-H2O2oxidation system, the carbonyl content, surface hydrophobicity, turbidity andbityrosine content increased with the concentration of H2O2; compared with the nonoxidized MP, thecontents of cysteine, methionine and tyrosine decreased by13.3%,11.6%, and20.5%after beingoxidized with20mmol/L H2O2, respectively. Low-field NMR and hydrogen proton density resultsshowed that the immobile water population in MP gel decreased by18.81%, the free water increased by85.56%and oxidation could decrease the water content in MP gel. These indicated that the texuture ofMP gel decreased with the degree of protein oxidation; the microstructure of MP gel was severelydestructived by protein oxidation; the higher of the degree of protein oxidation was, the severer of“water state transformed”, and the lower of the WHC of MP gel were (P <0.05).The protein oxidation occurred during the thawing process; the oxidation induced aggregation,degregation and denaturation of protein, resulted in destruction of the microstructure of muscle fibribundles, and decreasing of WHC of muscle, leading to the thawing loss and debasement of the qualityof meat. Compared with the normal4℃thawing (refrigerator thawing, RT), the novelfluctuated-low-temperature combined with high-relative-humidity thawing (FT) could significantlydecrease the degree of protein oxidation (carbonyl content decreased0.75, sulfydryl content increased13.11nmol/mg pro), thawing loss, drip protein content and cooking loss decreased by3.12%,4.89%and1.63%, SDS-PAGE and DSC results showed that protein denaturation degree of control groupsignificantly higher than test group, Scan and transmission electron microscopes showed the novelthawing method could retard the shrinking of muscle fibre and water state transformation (P <0.05),which will eventually reduce the thawing loss (P <0.05), improve the quality of thawed beef.A novel FT storage was developed. A18×10×5m storage thawed20t frozen beef in12h need49.19g/s steam and three fans, which power was7kW and air volume was4000m3/h. The pilotexperiment showed that compared with the normal4℃thawing storage, the novel thawing storagecould significantly decrease the thawing loss and cooking loss of beef, reducing weight loss; Decresethe protein content of thawing drip, reducing nutrition loss; Increase the hardness and chewiness of beef,improving the texture of beef; Decrease the oxidation of beef pigment, improving the color of beef, andeventually realize the fresh-keeping thawing of frozen beef and improve the quality of beef.