| Pre-conditioned meat products have become one of the most popular meat products for their convenience and delicacy.Traditionally,Na Cl and phosphate can improve the juiciness,tenderness,and color of meat and meat products as well as prolong their shelf life.However,excessive intake of sodium and phosphorus may cause potential health problems.Therefore,there is an urgent need for a new natural additive to replace Na Cl and phosphate in meat and meat products.This study focused on the effects of L-arginine（Arg）and L-lysine（Lys）on physicochemical properties,oxidation properties,and sensory attributes of prepared pork chops during refrigerated storage.On this basis,the mechanism of enhanced meat tenderness by Arg and Lys was further improved.The preliminary conclusions are as follows:1.Effects of Arg/Lys on physicochemical properties and sensory quality of prepared pork chops during refrigerated storage.Compared with control and positive control（STP）,Arg or Lys could increase p H,a* value,and water content（P<0.05）,and reduce L*,b*value,purge loss,and cooking loss（P<0.05）.Simultaneously,Arg or Lys could significantly improve the tenderness of meat（P<0.05）,increase the swelling of muscle fiber and accelerate the dissolution of myofibrillar protein.Additionally,compared with control and STP,Arg or Lys could significantly decrease the carbonyl content and increase the total sulfhydryl content of myofibrillar protein during refrigerated storage（P<0.05）.The total volatile basic nitrogen（TVB-N）of samples treated with Arg or Lys was lower than others in short-term storage（P<0.05）,although higher TVB-N was observed in the final stage of storage.At the same time,both Arg and Lys could effectively improve the texture（P<0.05）and sensory properties（P<0.05）of prepared pork chops compared with control.2.Effects and mechanism of Arg/Lys on the tenderness of pork during refrigerated storage.Compared with control,Arg or Lys could significantly decrease the shear force（P<0.05）and increase the myofibrillar fragmentation index of samples（P<0.05）.Compared with control,Arg or Lys could significantly increase the p H value of samples（P<0.05）and decrease the concentration of free Ca2+in muscle cells（P<0.05）.According to the casein zymography of calpains,Arg or Lys maintained the activity of calpain-1 in the first two days of storage,then accelerated the inactivation of calpain-1.The activity of native calpain-2 was higher in the other treatment groups compared with control on the seventh day of storage.The results of western blot and SDS-PAGE showed that Arg or Lys could inhibit the degradation of desmin,troponin-T,titin,and nebulin.According to the transmission electron microscope images of different samples,compared with control,the damage degree of Z-disc in the Arg and Lys treatment group was less,and the damage degree of the M-line was greater.Both Arg and Lys could maintain the solubility of pork myofibrillar protein and promote the dissolution of myosin and titin.In conclusion,Arg and Lys might play a leading role in improving the process of meat tenderization by weakening the molecular interaction between myofibrils. |
