Effects of thermal processing on N,N-dimethylpiperidinium (mepiquat) formation in meat and vegetable products

N,N-dimethylpiperidinium (mepiquat) is an important food contaminant formed from natural ingredients during thermal processing. In this study, mepiquat formation in meat (pork and beef) and vegetables (potatoes and broccoli) was investigated via HPLC-MS/MS; the investigated cooking methods were oven baking, pan cooking, deep frying, and microwaving. The results showed that, among all foods, oven-baked potatoes showed the highest mepiquat level of 1064 μg/kg, which appeared after 20 min at 240 °C. The residual rates of mepiquat precursors, pipecolic acid (PipAc), betaine, choline, and trigonelline, were determined in oven-baked potatoes to investigate their correlation with mepiquat formation. The PipAc levels reduced by 99.8% at 260 °C after 30 min of oven baking, exhibiting a significantly high decomposition rate. Therefore, PipAc could be used as a marker of quality for the detection of mepiquat in thermally processed foodstuffs.