Inhibitory effect of mulberry leaf (Morus alba L.) extract on the formation of free and bound heterocyclic amines in pan-fried muscovy duck (Cairina moschata) patties

The effect of different levels (0.01%, 0.03%, 0.05% and 0.10%) of mulberry leaf (Morus alba L.) extract (MLE) on the formation of free and bound heterocyclic amines (HCAs) in pan-fried muscovy duck (Cairina moschata) patties were investigated for the first time. Precursors of HCAs, oxidant index of patties and phenolic composition of MLE were measured. The total free and bound HCAs levels in control samples were 28.37 ng/g and 1935.65 ng/g, and the inhibition rates were 6.71-68.92% and 6.71-14.05% in MLE treatment groups, respectively, and 0.03% showed the strongest inhibitory effect. OPLS-DA result indicated that MeIQ, 8-MeIQx and Norharman were crucial differential compounds in total HCAs. Furthermore, the addition of MLE significantly inhibited the lipid and protein oxidation of patties (P < 0.05). Fifteen phenolic compounds, mainly flavonoids, were identified by LC-MS. The mitigation of HCAs and oxidation may be attributed to them. Correlation analysis indicated that the total HCAs content was negatively correlated with precursors but positively correlated with oxidation. In conclusion, MLE helped mitigate HCAs formation during muscovy duck processing and appeared to be a viable natural additive for producing healthier processed meat products.