Effect of freeze-thawing cycles on the quality properties and microstructure of pork muscle.

【Objective】 The effects of freeze-thawing cycles on pork quality properties and microstructure were investigated.The purpose of this study was to provide a scientific basis for meat preservation.【Method】 The porcine longissimus dorsi(LD) were frozen for 7 d under -26℃,then thaw by lotic water(room temperature,18℃).The effects of freeze-thawing cycles on thawing loss(TL),cooling loss(CL),cutting force(CF),microstructure,color(L*,a*,and b*-values),TBARS(thiobarbituric acid-reactive substances) of pork were studied.【Result】 The results showed that freeze-thawing cycles significantly increased the TL,CL,TBARS,L*-values and b*-values,and decreased a*-values(P0.05).The scanning electron micrograph of pork muscle showed that freeze–thawing cycles increased the space between fiber,torn and confused muscle fiber bundles,and breakdown muscle endometrial.The pork CF subjected one freeze-thawing cycle was significantly higher than that of fresh pork,and was gradually lower after multiple freeze-thawing cycles.【Conclusion】 The results demonstrated that freeze-thawing cycles seriously damaged microstructure of muscle and declined the quality properties of pork.