Investigation Of Gelation Functionalities Of Protein Extracted From Pale,Soft And Exudative-Like Chicken Breast Induced By Pulsed Electric Field

Under the background of globalization and the growing consumer awareness of the link between diet and health,poultry meat production has dramatically increased and chicken meat is preferred for its high-quality protein,low fat content and a lack of religious constraints.However,pale,soft,exudative(PSE)-like chicken meat continues to be an inevitable obstacle to the development of the poultry processing industry throughout the world because of its pale poor colour,soft texture and low water retention capacity.Modifications to the physicochemical properties and structure of muscle proteins can largely determine the functional properties of processed meat products,such as water holding capacity and gelation.The application of pulsed electric field(PEF),a non-thermal food processing technique,is attracting increasing attention from academia and food industry due to its instantaneous treatment,sustainability and environmental friendliness.The electric field energy induced by PEF treatments resulted in the conformational changes of protein,such as unfolding and aggregation,thus contribute to the improvements of gel quality.However,the optimal treatment condition and mechanism of PEF technology in improving the gel functional properties of PSE-like chicken protein are under investigation.Therefore,the aim of this study is to explore the relationship between the physicochemical,structural properties and gel functional properties of proteins extracted from PSE-like chicken breast meat treated by PEF,and propose a possible underlying mechanism,improving the commercial value of abnormal meat product in the poultry processing industry and facilitating a better understanding of the industrial applications of this emerging food processing technology.The main research contents and results are as follows:1.Effect of PEF on the solubility and structural properties of proteins extracted from PSE-like chicken breast meatThis chapter was performed to clarify the effects of PEF on the physicochemical properties and conformations of PSE-like chicken meat proteins.Various PEF parameters,including the electric field intensity(8,18,28 k V/cm)and pulse frequency(600,800,1000Hz),were explored.The residence time(3 min)and duty ratio(47%)used in this experiment remained unchanged.The results showed that the effect of the PEF intensity on the solubility and conformational change of PSE-like chicken protein was significantly greater than that of the pulse frequency,and the optimal treatment conditions were electric field intensity of 18 k V/cm and frequency of 800 Hz.The solubility and dynamic stability of the proteins increased steadily with increasing PEF intensity and pulse frequency.PEF could induce the expansion of protein structure,the moderate exposure of hydrophobic and sulfhydryl groups was conducive to the interactions between proteins and water.However,the intensity exceeded 18 k V/cm and 800 Hz,the solubility and active group contents of proteins declined due to the increasing amount of aggregates formed by mutually attractive polar protein molecules.In summary,PEF technology could effectively improve the solubility of PSE-like chicken proteins,and the optimal PEF treatment conditions(8,18,28 k V/cm,800 Hz,47%,3 min)were chosen as the subsequent study of the functional properties of PSE-like chicken protein gel.2.Effect of PEF on the gelation properties of proteins extracted from PSE-like chicken breast meatIn this chapter,the effect of various PEF intensities(8,18,and 28 k V/cm)on the gelation properties of PSE-like chicken meat proteins was investigated.The results demonstrated a positive correlation between gelation properties(gel strength and water holding capacity)and PEF intensities in the range of 8-18 k V/cm was observed,and a further increase in intensity had a negative impact.Optimized PEF treatment(18 k V/cm)was capable of inducing protein particles with smaller and more uniform size distribution,increasing the value of G’,G’’ and the proportion of immobilized water in the gel system,as it would provide conditions for external free water to act on the protein gels,thus contributing to the production of a more homogeneous and dense three-dimensional gel network structure.3.Exploration of the structural changes of PSE-like chicken breast meat protein treated by PEF: a molecular dynamics simulation methodTo clarify the mechanism of the optimal PEF treatment(18 k V/cm)on the molecular conformation of PSE-like chicken proteins,this chapter provided a novel molecular dynamics simulation technology to establish PEF simulation system.The results showed that,the secondary structure of the protein conformation changed obviously during the 30 ns PEF simulation,manifested as the decrease in α-helix content and then increased contents of other secondary structures.The root-mean-square-fluctuation value of protein molecules and the number of hydrogen bonds showed an upward trend in the electric field simulation system.The cross-linking reaction between protein-protein molecules or protein-water molecules through hydrogen bonds could stabilize the structure of new protein aggregates and improving the solvation effect of the proteins.The value of the gyration radius further decreased with the extension of the simulation time,indicating that the conformation compactness of the protein increased,thus contributing to the production of a more homogeneous and dense protein gel network structure.