Dynamic Effect of NaCl Concentration on Intramuscular Lipid Hydrolysis and Oxidation in Pork

To investigate the effects of different NaCl concentration on intramuscular lipid hydrolysis and lipid oxidation in pork processing, 1%, 2%, 3%, 4%, and 5% of NaCl were added to the longsissimus muscles, respectively. Then kinetic changes of triglyceride, phospholipid, free fatty acid, and lipid oxidation were described after treatment at different temperature range of 15~30 ℃. The results showed that the hydrolysis of triglyceride and phosphollipid, and the lipid oxidation accorded with first-order kinetic model, and the change of free fatty acid could be fitted by zero-order kinetic model. The average rate constants of both lipid hydrolysis and free fatty acid formation increased with the increasing temperature or NaCl content, and phospholipid had bigger lipolysis rate constants than triglyceride. At a fixed NaCl content, the rate constants of lipid oxidation increased with the increasing temperature, and at a fixed temperature, lipid oxidation rate constants first increased and then decreased with the salt concentration, reaching a maximum at 3% salt concentration. The Arrhenius equation analysis showed that the activation energy of lipid hydrolysis decreased with the increasing NaCl content, and NaCl had a more significant effect on phospholipid than on triglyceride. Lipid oxidation had smallest activation energy at 3% NaCl. So, NaCl concentration had a different effect on lipid hydrolysis and lipid oxidation in pork, and its role on rate constant of lipid oxidation was much bigger than that of lipid hydrolysis.