Effects of oxidised linoleic acid on the formation of N ε ‐carboxymethyl‐lysine and N ε ‐carboxyethyl‐lysine in Maillard reaction system

Summary This study investigated the effects of oxidised linoleic acid (18:2) on N ε ‐carboxymethyl‐lysine ( CML ) and N ε ‐carboxyethyl‐lysine ( CEL ) formation in Maillard reaction systems. Model systems of lysine/glucose (L/G), lysine/18:2 (L/18:2), lysine/18:2/glucose (L/18:2/G), myofibrillar protein/glucose ( MFP /G), MFP /18:2 and MFP /18:2/G were maintained at 37 °C for 6 weeks. The results showed that CML/CEL contents in L/G (6.99 and 0.96 mmol mol −1 lysine, respectively) were significantly higher than those in L/18:2/G (1.43 and 0.41 mmol mol −1 lysine, respectively), and there is a small amount of CML/CEL generation in L/18:2. However, the CML/CEL levels in MFP/G (197.2 and 83.8 ng mg −1 protein, respectively) were markedly lower than those in MFP /18:2/G (283.2 and 118.5 ng mg −1 protein, respectively). 18:2 favours the formation of CML/CEL in MFP /18:2/G, not in L/18:2/G. All these findings indicated that the role of 18:2 on CML/CEL formation in Maillard reaction system was complex, and depended on CML/CEL formation rate and substrate types (lysine or lysine residue in protein).