Quantitation of 13 Heterocyclic Aromatic Amines in Cooked Beef, Pork, and Chicken by Liquid Chromatography−Electrospray Ionization/Tandem Mass Spectrometry

Abstract

The concentrations of heterocyclic aromatic amines (HAAs) were determined, by liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-ESI-MS/MS), in 26 samples of beef, pork, and chicken cooked to various levels of doneness. The HAAs identified were 2-amino-3-methylimidazo[4,5- f]quinoline, 2-amino-1-methylimidazo[4,5- b]quinoline, 2-amino-1-methylimidazo[4,5- g]quinoxaline (I gQx), 2-amino-3-methylimidazo[4,5- f]quinoxaline, 2-amino-1,7-dimethylimidazo[4,5- g]quinoxaline (7-MeI gQx), 2-amino-3,8-dimethylimidazo[4,5- f]quinoxaline, 2-amino-1,6-dimethyl-furo[3,2- e]imidazo[4,5- b]pyridine, 2-amino-1,6,7-trimethylimidazo[4,5- g]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5- f]quinoxaline, 2-amino-1,7,9-trimethylimidazo[4,5- g]quinoxaline, 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP), 2-amino-9 H-pyrido[2,3- b]indole, and 2-amino-3-methyl-9 H-pyrido[2,3- b]indole. The concentrations of these compounds ranged from <0.03 to 305 parts per billion (micrograms per kilogram). PhIP was the most abundant HAA formed in very well done barbecued chicken (up to 305 microg/kg), broiled bacon (16 microg/kg), and pan-fried bacon (4.9 microg/kg). 7-MeI gQx was the most abundant HAA formed in very well done pan-fried beef and steak, and in beef gravy, at concentrations up to 30 microg/kg. Several other linear tricyclic ring HAAs containing the I gQx skeleton are formed at concentrations in cooked meats that are relatively high in comparison to the concentrations of their angular tricyclic ring isomers, the latter of which are known experimental animal carcinogens and potential human carcinogens. The toxicological properties of these recently discovered I gQx derivatives warrant further investigation and assessment.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation and fate: an example of the coordinate contribution of lipid oxidation and Maillard reaction to the production and elimination of processing-related food toxicants

“…13,15,16 PhIP is typically found in foods at amounts up to 35 ng/g, 17 but there are reports of higher levels, especially in fried and barbecued chicken. 18 The mechanism by which PhIP is produced has been the 35 objective of different studies but it has not been fully elucidated until very recently.…”

“…3 Formation of formaldehyde and ammonia from phenylacetaldehyde, phenylalanine or creati(ni)ne. 15 4 Final assembly of the molecule by incorporating formaldehyde and ammonia. Obviously, although steps 1, 2, and 4 have to take place sequentially, step 3 can take place simultaneously to steps 1 or 2.…”

“…35 However, in the course of lipid oxidation, many compounds analogous to α-dicarbonyl compounds are produced which are able to degrade amino acids similarly to the α-dicarbonyl compounds derived from carbohydrates. 15 The Strecker degradation of amino acids produced by secondary lipid oxidation products was firstly described in 2004 for the formation of phenylacetaldehyde by phenylalanine degradation in the presence of epoxyalkenals, 26 and later extended to other lipid-derived reactive carbonyls. [36][37][38] aldehyde formation by lipid oxidation products is believed to be produced analogously to amino acid degradation by α-dicarbonyl compounds.…”

“…13 Maillard reaction and lipid oxidation are not two independent processes. In fact, lipid oxidation products influence Maillard 15 pathway and vice versa, and there are common intermediates and analogous polymerization mechanisms in both routes conducting to food browning. 14 The objective of this review is to collect the scattered existing information suggesting that this coordinate contribution of both lipid oxidation and Maillard reaction to food 20 browning is also playing a role in the formation and fate of heterocyclic aromatic amines.…”

“…10 The formation pathway of 2-amino-1,6-dimethylimidazo[4,5-b]pyridine (DIMP) can also be hypothesized to be produced analogously by starting from propanal in the place of phenylacetaldehyde (Scheme 3). Propanal is not a Strecker aldehyde derived from amino acids, but it is a major oxidation 15 product of n3 fatty acids. 30 Analogously, 2-amino-1,5,6-trimethylimidazo[4,5-b]pyridine (1,5,6-TMIP) can be hypothesised to be produced analogously to DIMP but with acetaldehyde in the place of formaldehyde to close of the pyridine ring (Scheme 3).…”