Study On The Effect Of Exogenous Lysine And Arginine On The Water Holding Capacity Of The Frozen Porcine Longissimus Lumborum And Its Mechanism

Freezing is an effective technical method to prolong the shelf-life of meat and meat products.However,freezing will inevitably lead to the decline of quality attributes and value of meat and meat products.Therefore,it is of great significance to develop some safe and effective cryoprotectants to improve the quality attributes of frozen meat.In this study,the effects of Arg and Lys on the quality attributes of the frozen porcine Longissimus lumborum were observed.Based on the aforementioned studies,the mechanism of Arg and Lys on the water-holding capacity of the frozen porcine Longissimus lumborum was studied.Compared with the blank control,thawing loss,cooking loss,shear force,L*value and b*value of the groups treated with Arg and Lys were significantly decreased（P<0.05）,while a*value was significantly increased（P<0.05）.Histological and transmission electron microscopy observation showed that Arg and Lys treatment could reduce the damage of ice crystals formed in muscle fibers during freezing,contributing the superior quality of frozen meat.Arg and Lys treatment significantly increased the Ca²⁺-ATPase activity of the myofibrillar proteins（MPs）,and significantly reduced the surface hydrophobicity（P<0.05）.Arg and Lys treatment significantly increased the content of immobilized water（P<0.05）,and effectively improved the water-holding capacity of muscle.Compared with the blank control,Arg and Lys treatment significantly increased the content of extractable MPs,MPs solubility,free amino content,tryptophan fluorescence intensity,dityrosine content,total sulfhydryl content and relative content ofβ-sheet of frozen porcine Longissimus lumborum（P<0.05）,and significantly reduced the carbonyl content and relative content ofα-helix structure（P<0.05）.DSC results showed that Arg and Lys treatment significantly increased the denaturation temperature of myosin head portion(T_max1),denaturation temperature of myosin tail portion(T_max2),and denaturation enthalpy of myosin head portion（ΔH₁）of frozen porcine Longissimus lumborum and decreased the denaturation temperature of actin（Tmax₃）,denaturation enthalpy of myosin tail portion（ΔH₂）and denaturation enthalpy of actin（ΔH₃）（P<0.05）.Arg and Lys treatment could significantly increase the band intensity of myosin heavy chain,light chain,and actin in MPs of frozen porcine Longissimus lumborum（P<0.05）,and the fragment of myosin heavy chain was not found.Arg and Lys treatments effectively maintained the conformation of MPs（tryptophan fluorescence,zeta-potential）and reduced the aggregation of myosin heavy chain induced by disulfide bond during freezing.