Inhibitory profiles of spices against free and protein-bound heterocyclic amines of roast beef patties as revealed by ultra-performance liquid chromatography-tandem mass spectrometry and principal component analysis

The effects of various levels of chili pepper, Sichuan pepper, and black pepper on the amounts of 17 heterocyclic amines (HAs) from seven categories of both free and protein-bound states in roast beef patties were assessed by ultra-performance liquid chromatography-tandem mass spectrometry combined with principal component analysis. Three groups of HA, including imidazopyridines (DMIP), imidazoquinoxalines (MeIQx and 4,8-MeIQx), and beta-carbolines (norharman and harman), were detected and quantified in both their free and protein-bound states, whereas PhIP was detected only in its free state, and imidazoquinolines (IQ, IQ[ 4,5-b], and MeIQ), alpha-carbolines (A alpha C and MeA alpha C), and phenylpyridines (Phe-P-1) were detected only in their protein-bound states. The results demonstrate that the peppers at all three levels had significant inhibitory effects on free PhIP, DMIP, MeIQx, and 4,8-DiMeIQx and could promote free norharman. Harman was significantly suppressed by chili pepper and black pepper, but enhanced by Sichuan pepper. All 11 protein-bound HAs, with the exception of IQ, IQ[ 4,5-b], and MeIQx with added chili pepper, were significantly reduced by the three peppers. The total amounts of the free and protein-bound states of all 11 HAs (1692.4 +/- 78.9 ng g(-1)), imidazopyridines (5.5 +/- 0.2 ng g(-1)), imidazoquinolines (7.2 +/- 0.2 ng g(-1)), imidazoquinoxalines (6.9 +/- 0.2 ng g(-1)), a-carbolines (20.1 +/- 0.4 ng g(-1)), and beta-carbolines (1651.7 +/- 79.5 ng g(-1)) were suppressed by each level of all of the three peppers except for 0.5% and 1.0% chili pepper. Our findings may facilitate the inhibition of HA formation in the processing of meat products.