Effect Of Cooking Methods On The Quality And Oxidative Properties Of Chicken PSE-like Meat And Normal Meat

Chicken,which constitutes more than 90%of the demands in the poultry market,is considered an excellent source of protein and a healthier dietary alternative than red meat.Therefore,the quality of chicken meat is increasingly important to enterprises and consumers.However,one type of myopathic poultry chicken meat is of concern because of its pale,soft texture and high exudative loss(PSE),which resembles myopathic pork.At present,PSE-like meat accounts for more than 40%of the unprocessed poultry products sold in the market and is directly available to consumers for domestic cooking.However,the differences between PSE-like meat and normal meat after being cooked are rarely noticed.Domestic cooking methods can be divided into several categories,including dry(roasting),moist(boiling and steaming),and novel heating(microwaving).Each cooking method has its specific characteristics,ranging from the heat transfer method,heat transfer medium,cooking time and temperature.These different cooking conditions not only lead to different changes in the structure of the meat,which can affect the final quality and palatability of the product,but also cause a range of physical and chemical changes,including oxidation of the meat,which has a potential negative impact on human health.However,there are very limited reports on the differences in quality and oxidation of PSE-like chicken meat after cooking,which is not conducive to the development of sensory and textural qualities of quality-deficient meat.Currently,LC/MS/MS-based proteomics techniques have been widely used to identify specific proteins and detect changes in low abundance at the molecular level,which can identify qualitative and quantitative differences in proteins associated with processing parameters,including cooking procedures.Also,this is crucial for the development and utilization of defective meats.In addition,due to the complex mechanism and numerous oxidation products of protein oxidation,screening for differential proteins will facilitate our understanding of the effects of processing on defective meat,it will also identify specific proteins and reveal the location and nature of amino acid residues undergoing modification,and provide a marker and a basis for dietary health selection and identification of PSE-like chicken meat.Therefore,this paper focuses on the effects of cooking methods on the quality and oxidation of PSE-like chicken meat versus normal chicken meat,and analyzes the mechanisms of meat quality changes and protein oxidation caused by cooking.The results of the study will promote more refined guidance and control strategies for the processing of defective meats in order to safeguard their nutritional and functional properties.At the same time,it can provide recommendations and practical guidelines for family consumption of PSE-like chicken meat.The main studies are as follows:1.The effect of cooking methods on the structural and quality characteristics of PSE-like meat and normal meat.The pectoralis major muscle of broiler chickens was used as the object of study.PSE-like meat and normal meat were screened by pH,L*value and purge loss at 24 h after slaughter.Four domestic cooking methods(steaming,boiling,roasting and microwaving)were used to process two types of chicken meat to a core temperature of 60,70 and 80?.The differences in pH,color,cooking loss rate,muscle fiber diameter,myofibril fragmentation index(MFI),shear force,texture,sensory characteristics and microstructure were analyzed to investigate the changes in physicochemical properties,sensory characteristics and meat quality between PSE-like meat and normal meat under different cooking methods.The results showed that PSE-like meat has a weaker myofibrillar structure,and the difference of meat quality between PSE-like meat and normal meat gradually increased with increasing core temperature.When the core temperature reached 80?,BO and ST treatments caused severe structural damage to PSE-like meat;manifested by severe decreases in color,shear force,texture,sensory attributes,and increases in cooking loss rate and MFI.RO treatment,on the other hand,caused PSE-like meat to have the highest hardness,shear fore and toughness,resulting in severe contraction of the meat's muscle fiber diameter,which ultimately results in the decline of palatability of meat and the difficulty in chewing.MV treatment had the least effect on the difference in meat quality between PSE-like meat and normal meat.Therefore,to ensure the quality and palatability of PSE-like meat,the use of MV treatment may be a reliable way to consume PSE-like meat at home.In addition,the color attributes(a*and L*)of PSE-like meat at a core temperature of 60? are not significantly different from normal meat at 70?.If consumers only use the appearance as an indication of the cooking maturity of PSE-like meat,it may pose some visual errors and safety hazards.2.Comparative study of cooking methods on protein oxidation in PSE-like meat and normal meat.Based on the classification and processing in Chapter 2,the relationship between the occurrence,intensity of protein oxidation and the meat quality of the two types of chicken meat during cooking were clarified by comparing the contents of carbonyl,sulfhydryl,malondialdehyde and disulfide bonds,fluorescence intensity of Schiff base and tryptophan,and modification state of amino acid residues between PSE-like meat and normal meat under different cooking processes.The results showed that PSE-like meat has a high oxidation sensitivity,and the heat treatment process will increase the oxidation sensitivity of PSE-like meat and produce more oxidation products.This is evidenced by the contents of a decrease in tryptophan and sulfhydryl groups,an increase in malondialdehyde and carbonyl groups,and an enhanced degree of protein cross-linking and aggregation during heat treatment.Among them,RO treatment led to excessive oxidation and aggregation of proteins in PSE-like meat,with BO and ST coming after them and MV caused the least effect.In addition,almost the majority of amino acid side chains are very susceptible to oxidative damage during cooking,forming various types of oxidative modifications.RO treatment caused amino acid residues to reach the highest intensity of different types of modifications and produced higher levels of the number and type of oxidative modifications(O3).ST and BO treatments had a more prominent effect on the extent of protein degradation,causing the production of more peptides in protein degradation and inducing oxidative modifications of a greater number and variety of amino acid residues.PCA analysis showed that there was a correlation between oxidative damage and meat quality under heat treatment,and that protein oxidation during processing played a role in the formation of meat texture.Thus,MV treatment significantly reduced the variability of protein oxidation between PSE-like meat and normal meat,as well as the potential health risk of oxidative modification of amino acid residues.3.Proteomic study of cooking methods on the difference in quality between PSE-like meat and normal meat.Based on the conclusion in Chapters 2 and 3,Label-free proteomics was used to analyze the changes of the differentially expressed proteins of PSE-like meat and normal meat under different cooking processes.The results showed that a total of 572 unique peptides were identified in PSE-like meat and normal meat,and 84(ST),89(BO),50(RO)and 43(MV)differentially expressed proteins(DAPs)were respectively screened on the basis of the change of multiples>2.0 or<0.5,P<0.05.Twenty significant proteins related to color and textural attributes were screened by PCA,PLS-DA,and VIP.These DAPs are mainly involved in protein structure,metabolic enzyme and oxidation stress.Some structural proteins(myofibrillar protein and connective tissue protein)and sarcoplasmic proteins(mostly metabolic enzymes,oxidoreductases,and stress proteins)are associated with the cellular process regulation,protein turnover,skeletal muscle contraction,and energy metabolism.These proteins play an important role in maintaining the structure and function of normal meat tissues during processing,and they may also be a key factor in the deterioration of PSE-like meat quality during cooking.Moreover,the different cooking methods can induce collagen dissolution.The light scattering caused by enhanced protein gelation leads to an enlarged light reflection,resulting in higher L*values for PSE-like meat.Meanwhile the different cooking methods can also cause complete coagulation of myosin molecules and pigment oxidation(heme groups),resulting in a decrease in a*values of PSE-like meat.Therefore,collagen(COL1A1,COL1A2,COL3A1,COL6A3,COL6A1),promyoglobin(TPM2),myoglobin(MB)and hemoglobin(HBE)were considered as potential markers affecting the color stability and changes of PSE-like meat during thermal processing.The DAPs results open up new possibilities for modifying the quality of PSE-like meat during different cooking processes.