Formation of free and protein-bound carboxymethyllysine and carboxyethyllysine in meats during commercial sterilization.

The effect of commercial sterilization treatments on the levels of advanced glycation endproducts (AGEs) in meats was investigated. The amounts of both free and protein-bound N(ε)-carboxymethyllysine (CML) and N(ε)-carboxyethyllysine (CEL) in beef (rump, ribeye, short plate), pork (hind leg, tenderloin, belly), and chicken (chicken breasts, drumsticks) were determined using an HPLC-MS/MS method. Beef and pork had a small proportion (raw <15%; sterilized <8%) of free AGEs compared to the total AGEs, but raw chicken breasts had very high levels of free CEL (7.12±9.98 mg/kg; n=13) with large biological variation compared to pork (0.19±0.09 mg/kg; n=9) and beef (0.44±0.19 mg/kg; n=9). Commercial sterilization (121°C for 10 min) did not significantly affect the amounts of free CML or CEL, but led to about 0.6- to 3.6-fold increase of protein-bound CML and CEL. The amounts of protein and fat content in beef or pork had very little effect on the formation of protein-bound AGEs during sterilization process.