Inhibitory effects of trans-cinnamaldehyde on Harman and Norharman formation in spiced pork shoulders: Mechanisms and chemical models

This study investigates the inhibitory effects of trans -cinnamaldehyde (TCA) on Harman and Norharman formation in spiced pork shoulders and chemical models, elucidating the underlying mechanisms. Our results demonstrate that TCA significantly reduces the levels of these compounds, with optimal inhibition observed at 0.1 mg/mL TCA in spiced pork shoulders (80.2 % reduction in Harman, 94.7 % reduction in Norharman) and 0.1 mmol TCA in chemical models (89.1–90.2 % reduction in Harman, 88.7–99.2 % reduction in Norharman). For the first time, two potential reaction mechanisms by which TCA inhibits the formation of HAAs are proposed: TCA can react with tryptophan to form adducts or directly scavenge HAAs. Notably, quantum chemical theoretical calculations indicate that the reaction energy barriers (108.3 kJ/mol and 156.0 kJ/mol) for the TCA-tryptophan reaction to form an aldimine were significantly lower than those (123.2 kJ/mol and 187.2 kJ/mol) for the glucose-tryptophan reaction to form a Schiff bases. Therefore, Compared to the glucose-tryptophan reaction, the TCA-tryptophan reaction is more likely to occur. Mass spectrometry analysis further confirms the presence of TCA-tryptophan adduct compounds, supporting the proposed mechanisms. These findings may provide more theoretical foundation researches for the development and research of HAAs inhibitors in the future.