Combination effects of salts and cold storage on the formation of protein-bound Nɛ-(carboxymethyl)lysine and Nɛ-(carboxyethyl)lysine in raw and subsequently commercially sterilized ground pork

The effects of cold storage (0 °C, 0-8 days) and salts (NaCl, 0.5-5%; NaNO2, 50-150 mg/kg) on the formation of protein-bound Nɛ-(carboxymethyl)lysine (CML) and Nɛ-(carboxyethyl)lysine (CEL) in raw and subsequently commercially sterilized (121 °C, 10 min) pork were investigated. Based upon two-factor analysis of variance (α = 0.05), there was no significant interaction effect between salts and storage time on the levels of CML and CEL in raw or sterile pork; salts and storage time did not significantly affect the amounts of CML and CEL in raw pork. However, in sterile pork, 1.5-5% NaCl treatments led to an average of 7.5-52.6% increase in CML, while NaNO2 resulted in 25.4-37.1% and 21.4-23.4% reduction in CML and CEL, respectively; raw pork stored for 8 days led to 82.5% increase of CML and 32.6% increase of CEL in the sterile products (n = 30), as compared to those without cold storage.