Effects of NaCl concentration and potassium chloride substitutions on the thermal properties and lipid oxidation of dry-cured pork.

The thermal properties of cured meat are important for determining storage life and nutritional quality. However, few studies have focused on the thermal properties of dry-cured pork, particularly in relation to salt level and type. In order to study the thermal properties of dry-cured pork, we used differential scanning calorimetry (DSC) to evaluate the net heat energy (enthalpy, ΔH), onset (T(onset)), and maximum (T(max)) temperatures of different pork cuts salted with mixtures of chloride (NaCl and KCl) salts within the curing and ripening temperature range. Within the curing temperature range (-5 to 20 °C), the T(onset), T(max), and ΔH of cured meat treated with different NaCl : KCl mixtures were generally lower than for fresh meat, which indicates that the addition of NaCl or KCl can reduce the melting of lipids and water (especially lipids), in different pork cuts. Within the ripening temperature range (5 to 50 °C), heat absorption peaks in belly and leg cuts were between 29 and 33 °C. However, no obvious heat absorption peak was found in loin cuts. Compared to non-KCl substitutions, a slightly higher KCl substitution could significantly (P < 0.05) enhance ΔH values of dry-cured belly and leg cuts. The likely cause of this phenomenon is that high KCl substitutions promote lipid oxidation (r = 0.98, for belly; r = 0.95, for leg cuts). Therefore, KCl substitution should be no more than 30% (wt/wt), especially for high lipid pork, to prevent excessive melting and oxidation of lipids during the dry-curing process.