Relative exposure to beta-carbolines norharman and harman from foods and tobacco smoke.

Norharman and harman are two heterocyclic beta-carboline (9H-pyrido[3,4-b]indole) alkaloids with biological and potential toxicological activity that appear in foodstuffs and environmental sources. To assess the occurrence and distribution of these compounds and to estimate the exposure levels based on the detected amounts, numerous samples of foodstuffs and cigarette smoke were analysed by solid-phase extraction and high-performance liquid chromatography-fluorescence. The levels found of beta-carbolines were highly variable. Low processed foodstuffs (i.e. milk, yoghurt, uncooked meats and fish) did not contain norharman and harman above the detection limit. Others, however, contained relatively high concentrations (at the tens of ng g(-1) or microg l(-1) level) depending on the processing conditions as, for example, 'well-done' cooked meat and fish. The highest amounts of norharman and harman were found in brewed coffee (29-207 microg l(-1)), sauces (soy sauce and Tabasco, among others; 4-252 microg l(-1)), 'well done' cooked meat and fish (57-160 ng g(-1)), toasted bread (42-160 ng g(-1)), and fermented alcoholic beverages (n.d.-41 mug l(-1)). beta-Carbolines also occurred in a high amount in the mainstream of cigarette smoke (207-2780 ng/cigarette), which is an important contributor to daily exposure to these compounds. Based on these results, it is concluded that the daily exposure to beta-carbolines in humans might be from tens to hundreds of micrograms, with cigarette smoke, coffee, certain seasonings, cooked foods and alcoholic beverages, in this order, being the major contributors. Many other foodstuffs might also contribute with minor amounts of norharman and harman. Foods and tobacco smoke might be potential contributors to the reported endogenous presence of beta-carbolines in humans.     

Analysis of heterocyclic amines and β-carbolines by liquid chromatography–mass spectrometry in cooked meats commonly consumed in Korea

Heterocyclic amines (HAs), which form in meats during heating and cooking, are recognized as mutagenic and carcinogenic compounds. In this study, 13 HAs and 2 β-carbolines (BCs) were analyzed in cooked Korean meat products, including griddled bacon, griddled pork loin, boiled pork loin, boiled chicken meat, chicken meat stock, chicken breast for salad and chicken patty. The samples were either cooked in the laboratory or purchased from local fast-food restaurants. The HAs and BCs in the samples were separated using solid-phase extraction and were analyzed by high performance liquid chromatography–mass spectrometry (HPLC–MS). The most frequently detected HAs and BCs in the cooked meats were harman (1-methyl-9H pyrido[4,3-b]indole; 990.9 ng g^?1), norharman (9H-pyrido[4,3-b]indole; 412.7 ng g^?1) and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine; 258.2 ng g^?1). The griddled pork loin and bacon contained higher levels of norharman, harman and PhIP than the other cooked meats. PhIP, which is classified as a Group 2B carcinogen by the International Agency for Research on Cancer, had levels of 258.2 and 168.2 ng g^?1 in the griddled pork loin and griddled bacon, respectively. The griddled bacon was the only sample containing TriMeIQx (2-amino-3,4,7,8-tetramethylimidazo[4,5-f]quinoxaline; 79.9 ng g^?1). IQ (2-amino-3-methyl imidazo[4,5-f]quinoline), 7,8-DiMeIQx (2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline), 4,8-DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline) and AαC (2-amino-9H-pyrido[2,3-b]indole) were detected at trace levels in all samples.     

Heterocyclic aromatic amines in meat products consumed in China

Heterocyclic aromatic amines (HAAs) formed in cooked muscle foods are recognized as mutagenic and carcinogenic compounds. A total of 9 nine HAAs were analyzed in 34 meat products consumed in China. The total HAAs content in all meat products ranged from 4.14 to 108.80 ng/g. Dry and sauced meats contained higher concentration of total HAAs than other kinds of meat products. Samples from East and Northwest China showed higher concentrations of total HAAs than samples from other regions. The most common specific HAAs, harman and norharman, were detected in all meat samples at levels of 1.09–63.97 and 1.19–62.30 ng/g, respectively. Concentrations of MeIQx, PhIP, 4, 8-DiMeIQx, and AαC were much lower. MeAαC (n=8), IQ (n=15), and Trp-P-2 (n=23) were detected in some samples.     

Influence of food condiments on the formation of carcinogenic heterocyclic amines in cooked chicken and determination by LC-MS/MS

Heterocyclic amines (HCAs) are known to be suspected human carcinogens produced by high-temperature cooking of protein-rich foods such as meat and fish. In the present study, the influence of numerous food condiments on the formation of HCAs in cooked chicken was investigated. Chicken samples were subjected to pan-frying under controlled temperature. The levels of HCAs DMIP, MeIQx, 4,8-DiMeIQx, PhIP, harman and norharman were found to be between 0.93 and 27.52 ng g^?1, whereas IQ, MeIQ, AαC, MeAαC, Trp-P-1 and Trp-P-2 were found either below the limit of quantification or not detected in the control sample. Nevertheless, for samples cooked using food condiments, the amounts of HCAs (DMIP, MeIQx, 4,8-DiMeIQx and PhIP) were between 0.14 and 19.57 ng g^?1; harman and norharman were detected at higher concentrations up to 17.77 ng g^?1 while IQ and MeIQ were at levels below the limit of quantification; and AαC, MeAαC, Trp-P-1 and Trp-P-2 were not detected in any of the samples. The outcomes revealed that the formation of HCAs (except harman and norharman) diminished after the addition of food condiments. Edible oil contributed to the highest levels of HCA formation, followed by garlic, paprika, pepper and tomato.     

The Effect of Heating Process Using Electric and Gas Ovens on Chemical and Physical Properties of Cooked Smoked-Meat

Study of potential of kenari (Canarium indicum L.) shell as a raw material in liquid smoke production for meat flavor developer has been done. To achieve this study, heating method using electric and gas ovens on the properties of the cooked smoke-meat have been carried out. The characterization of chemical properties (water content, protein content, fat content, TBA and the number of peroxide, physical properties (cooking loss, WHC, tenderness, color) cooked smoke-meat were analyzed using the Independent-Sample T Test. The results showed that protein and water contents as well as physical properties of electric oven- and gas oven-heated-cooked smoked meats were relatively the same. Fat content of electric oven-heated-cooked smoked meat was higher than that of oven gas-heated-cooked smoked meat. The TBA and peroxide values of electric oven-heated-cooked smoked meat were lower that gas oven-heated-cooked smoked meat.     

Inhibitory effects of pomegranate seed extract on the formation of heterocyclic aromatic amines in beef and chicken meatballs after cooking by four different methods

Beef and chicken meatballs with a 0.5% (w/w) pomegranate seed extract were cooked using four different cooking methods (oven roasting, pan cooking, charcoal-barbecue, and deep-fat frying) and six heterocyclic aromatic amines; IQ, MeIQx, 4,8-DiMeIQx, PhIP, norharman, and harman were observed. In the beef meatballs, the highest inhibitory effects of pomegranate seed extract on heterocyclic aromatic amines formation were 68% for PhIP, 24% for norharman, 18% for harman, 45% for IQ, and 57% for MeIQx. Total heterocyclic aromatic amine formation was reduced by 39% and 46% in beef meatballs cooked by charcoal-barbecue and deep-fat frying, respectively. In the chicken meatballs, the highest inhibitory effects were 75% for PhIP, 57% for norharman, 28% for harman, 46% for IQ, and 49% for MeIQx. When the pomegranate seed extract was added to the chicken meatballs cooked by deep-fat frying, the total heterocyclic aromatic amine formation was inhibited by 49%, in contrast the total heterocyclic aromatic amine contents after oven roasting increased by 70%.     

肉制品加工过程中harman和norharman形成机制研究进展

1-甲基-9H.-吡啶[3,4-b]吲哚(harman)和9H-吡啶[3,4-b]吲哚(norharman)是肉制品加工过程中形成的一类具有潜在毒性的β-咔啉生物碱,主要在高温体系下通过氨基酸裂解形成.本文概述肉制品加工过程中harman和norharman的形成机制,重点阐述加工方式对harman、norharman的作用规律,分析harman、norharman的前体物、生成途径及抑制措施,为肉制品加工工艺的革新和营养健康肉制品的开发提供基础.     

N-Nitrosothiazolidine and N-Nitrosothiazolidine-4-Carboxylic Acid in Smoked Meats and Fish

Various smoked meats including raw and fried bacon and both unsmoked and smoked (uncured) fish were analyzed for NThZ and NTCA. Most meat samples, bacons, and a few smoked fish contained traces of NThZ and considerably high (up to 13,700 ppb) levels of NTCA. Preliminary results indicated that raw bacons processed by old-fashioned direct smoking methods contained the highest (> 1,000 ppb) level of NTCA. Formation of NThZ from the NTCA present in smoked bacon increased with an increase in frying temperature as well as with frying time. NTCA level in the raw bacon and the cooking conditions seemed to be the most important factors involved in the formation of NThZ in the fried bacon. The reason for finding only insignificant levels of NThZ in smoked fish could not be established conclusively.     

Identification and occurrence of 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid: the main β-carboline alkaloid in smoked foods

Tetrahydro-β-carboline alkaloids are biologically active compounds that occur in foodstuffs. 1,2,3,4-Tetrahydro-β-carboline-3-carboxylic acid, a tetrahydro-β-carboline derived from a Pictet–Spengler condensation reaction among l-tryptophan and formaldehyde, was identified by GC–MS as its N-methoxycarbonyl methyl ester derivative in smoked fish, sausage and cheese. The occurrence of this β-carboline was determined by RP-HPLC-fluorescence in numerous commercially available samples of these products and the concentrations ranges were 0.03–12.2 μg/g, 0.07–6.06 μg/g and 0.01–14.8 μg/g in smoked fish, smoked cheeses and smoked sausages and meats, respectively. These results showed that 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid is the main β-carboline in such products. Smoked foods contained a higher relative amount (2–7 fold) of this compound in their exterior part exposed to the smoke than in their interior counterpart suggesting a reaction involving formaldehyde from smoke and tryptophan. Smoked products appear to be one of the food stuffs with the highest amount of this particular tetrahydro-β-carboline.     

The evaluation in the Ames test of the mutagenicity of tetrahydro-beta-carboline-3-carboxylic acids from smoked foods.

This paper reports the evaluation of five tetrahydro-beta-carboline carboxylic acids, formed from the interaction of woodsmoke carbonyls and tryptophan, for mutagenicity in the Ames test. Three of the compounds tested have been detected recently in smoked foods at levels in the micrograms/kg or mg/kg range. None of the compounds induced mutagenicity in TA 97, TA 98 or TA 100 strains of Salmonella typhimurium either with or without prior activation. However, tetrahydro-beta-carboline-3-carboxylic acid, and to a lesser extent 1-methyl-tetrahydro-beta-carboline-3-carboxylic acid were toxic to the strains of Salmonella typhimurium used. The inability of these beta-carbolines to induce mutation contrasts markedly with the mutagenicity of some beta-carbolines found in grilled meat products.     

Studies on the occurrence and formation of 2-(hydroxymethyl)-N-nitrosothiazolidine-4-carboxylic acid (HMNTCA) and 2-(hydroxymethyl)-N-nitrosothiazolidine (HMNTHZ) in various cured smoked meats,fish and cheese

Abstract : Because of the carcinogenic nature of many N-nitroso compounds, there is concern about their presence in foods. This paper presents some data on the levels of two non-volatile compounds (2-(hydroxymethyl)-N-nitrosothiazolidine-4-carboxylic acid (HMNTCA) and 2-(hydroxymethyl)-N-nitrosothiazolidine (HMNTHZ)) in various smoked foods such as 25 cured meats, eight smoked fish and seafoods, 15 smoked poultry products, and 17 smoked cheeses. All samples were negative for HMNTHZ, but 11 of the cured meats, six poultry products and two smoked fish contained HMNTCA at levels of 10–260 μg kg^?1. Upon frying, appreciable levels of HMNTHZ were formed in only one of 10 samples of cured meat products. The smoked cheeses were all negative for HMNTCA.     

Occurrence of heterocyclic amines in cooked meat products

Heterocyclic amines (HCAs), potent mutagens and a risk factor for human cancers, are produced in meats cooked at high temperature. The aim of this study was to determine the HCA content in cooked meat products (beef, chicken, pork, fish) prepared by various cooking methods (pan frying, oven broiling, and oven baking at 170 to 230 °C) that are preferred by U.S. meat consumers. The primary HCAs in these samples were PhIP (2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine) (1.49-10.89 ng/g), MeIQx (2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline) (not detected-4.0 ng/g), and DiMeIQx (2-amino-3,4,8-trimethyl-imidazo [4,5-f]quinoxaline) (not detected-3.57 ng/g). Type and content of HCAs in cooked meat samples were highly dependent on cooking conditions. The total HCA content in well-done meat was 3.5 times higher than that of medium-rare meat. Fried pork (13.91 ng/g) had higher levels of total HCAs than fried beef (8.92 ng/g) and fried chicken (7.00 ng/g). Among the samples, fried bacon contained the highest total HCA content (17.59 ng/g).     

熟肉制品中杂环胺的形成与抑制研究进展

杂环胺是熟肉制品中最常见的危害物,其种类繁多,形成途径复杂,抑制机制也不尽相同。本文介绍了2 类杂环胺的结构,主要阐述喹啉和喹喔啉类、2-氨基-1-甲基-6-苯基咪唑[4,5-b]吡啶、β-咔啉类（1-甲基-9H-吡啶[4,3-b]吲哚（1-methyl-9H-pyrido[4,3-b]indole,harman）、9H-吡啶[4,3-b]吲哚（9H-pyrido[4,3-b]indole,norharman））以及结合态杂环胺的形成途径,归纳减少杂环胺形成的措施及机理（控制加工条件和前体物、添加外源物质清除自由基和中间体、抑制美拉德反应等）,并对目前的研究现状进行概括。     

烹调肉制品中杂环胺的检测技术和控制手段研究进展

杂环胺是烹调肉和鱼等高蛋白食物过程中形成的一类致癌致突变化合物。本文概述烹调肉制品中杂环胺的前处理方法和检测技术,并重点阐述肉制品加工过程中产生杂环胺的控制手段。     

Formation of heterocyclic amines during cooking of duck meat

Heterocyclic amines (HAs) are an important class of food mutagens and carcinogens produced in meat cooked at high temperature. In the present study, the effects of various cooking methods: boiling, microwave cooking, charcoal-grilling, roasting, deep-frying and pan-frying on the formation of HAs in duck breast were studied. The various HAs formed during cooking were isolated by solid-phase extraction and analysed by HPLC. Results showed that both the varieties and contents of HAs and the cooking loss of duck breast increase along with increasing cooking temperature and time. Pan-fried duck breasts contained the highest amount of total HAs, followed by charcoal-grilling, deep-frying, roasting, microwave cooking and boiling. 9H-pyrido[3,4-b]indole (norharman) and 1-methyl-9H-pyrido[3,4-b]indole (harman) were detected in all of the cooked duck meat, with levels in the range of 0.1–33?ng?g^?1. 2-Amino-1-methyl-6-phenylimidazo[4,5-f]pyridine (PhIP) was formed easily in duck meat cooked by pan-frying and charcoal-grilling in the range of 0.9–17.8?ng?g^?1. 2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) was identified in duck meat cooked by charcoal-grilling and pan-frying, in the range of 0.4–4.2?ng?g^?1. 2-Amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx) was detected in amounts below 4.5?ng?g^?1 in duck meat cooked by charcoal-grilling, roasting, deep-frying and pan-frying. The other HAs were detected in amounts below 10?ng?g^?1. Colour development increased with cooking temperature, but no correlation with HAs’ content was observed.     

Microstructure and protein digestibility of beef: The effect of cooking conditions as used in stews and curries

Beef meat was cooked at 373 K for 10 and 30 min to investigate the effect of the cooking conditions generally used during beef stew and curry preparation on protein digestibility. The cooked meats, along with a raw control, were digested using an in vitro digestion model to simulate gastric and small-intestinal conditions. Samples taken at different digestion times were analyzed using SDS-PAGE, RP-HPLC, ninhydrin assays for amino N and transmission electron microscopy. Simulated gastric conditions quickly led to the loss of basic sarcomere structure in raw meat myofibrils whereas the sarcomere structure of the compact cooked meat myofibrils remained intact after 30 min of gastric digestion. Prolonged cooking of meat (30 min) resulted in incomplete digestion of small MW (<10 kDa) peptides, as observed from SDS-PAGE. This agreed with the amount of ninhydrin-reactive amino N released during digestion, which decreased with an increase in cooking time. The RP-HPLC peak areas of the major identified amino acids (tryptophan, tyrosine and phenylalanine) also decreased with an increase in cooking time. This suggested the formation of “limit peptides” during prolonged cooking of beef, which were not further broken down into free amino acids by digestive enzymes and therefore might not be bioavailable.     

Effect of cooking method on carnosine and its homologues, pentosidine and thiobarbituric acid-reactive substance contents in beef and turkey meat

Commercial samples of beef and turkey meat were prepared by commonly used cooking methods with standard cooking times: (1) broiled at 200 °C for 10 min, (2) broiled at a medium temperature (140 °C) for 10 min, (3) cooked by microwave (MW) for 3 min and then grilled (MW/grill) for 7 min, (4) cooked in a domestic microwave oven for 10 min, and (5) boiled in water for 10 min. The raw and cooked meats were then analysed to determine the carnosine, anserine, homocarnosine, pentosidine, and thiobarbituric acid-reactive substance (TBARS) contents. It was observed that boiling beef caused a loss of approximately 50% of the carnosine, probably because of the high water solubility of carnosine and its homologues; cooking by microwave caused a medium loss of the anti-oxidants of approximately 20%; cooking by MW/grill led to a reduction in carnosine of approximately 10%. As far as the anserine and homocarnosine contents were concerned, a greater loss was observed for the boiling method (approximately 70%) while, for the other cooking methods, the value ranged from 30% to 70%. The data oscillate more for the turkey meat: the minimum carnosine decrease was observed in the cases of MW/grill and broiling at high temperature (25%). Analogously, the anserine and homocarnosine contents decreased slightly in the case of MW/grill and broiling at a high temperature (2-7%) and by 10-30% in the other cases. No analysed meat sample showed any traces of pentosidine above the instrumental determination limits. The cooked beef showed an increased TBARS value compared to the raw meat, and the highest values were found when the beef was broiled at a high temperature, cooked by microwave or boiled in water. The TBARS value of the turkey meat decreased for all the cooking methods in comparison to the TBARS value of the fresh meat.     

N-nitrosamines and residual nitrite in cured meats from the Dutch market

A total of 140 samples of 16 kinds of cured meats were analyzed for contents of residual nitrite and N-nitrosamines. Nitrite was determined by reaction with sulfanilamide/naphthylethylenediamine and colorimetric measurement. N-nitrosamines were isolated from the samples by vacuum distillation and determined by gas-chromatography with chemiluminescence detection (GC-TEA). In six samples no nitrite was detectable (less than 1 mg NaNO2/kg), the remaining samples contained 1-140 mg NaNO2/kg, median value 6.8 mg/kg. In 46 samples (33%) no N-nitrosamines were detected, i.e. less than 0.1-0.5 microgram/kg of the individual nitrosamines, depending upon their structure. N-nitrosodimethylamine (NDMA) was the nitrosamine present most frequently, in 75 samples, contents were 0.1-0.9 microgram/kg, mean 0.3 microgram/kg. Other N-nitrosamines found were: N-nitrosopiperidine (NPIP), 10 times, 0.3-25 micrograms/kg; N-nitrosodiethylamine (NDEA), three times, 0.2-0.9 microgram/kg; N-nitrosopyrrolidine (NPYR), three times, 1.3-4.2 micrograms/kg; N-nitrosomorpholine, once, 0.7 microgram/kg and N-nitrosothiazolidine (NTHZ), 36 times, 0.5-91 micrograms/kg, mean 5.7 micrograms/kg. NTHZ was found most often and with the highest contents in smoked products. Frying of bacon and cured, smoked pork bellies led to substantially increased levels of NPYR in both products, and for the pork bellies also of NTHZ. In five samples of cured, smoked pork bellies after frying NTHZ-contents of 3.6-490 micrograms/kg (mean 179) were found. No correlation between residual nitrite levels and N-nitrosamine contents could be established. Investigations during the nineteen seventies gave much higher levels for NDMA, NDEA, NPIP and NPYR in Dutch cured meats than now found; at that time NTHZ was not measured.     

Effects of salt and some antioxidants upon the TBA numbers of meat

The effects of salt alone (2%) or coated with α-tocopherol or with Tenox 4 (BHA-citric acid-propylene glycol) or in a mixture containing BHA and BHT with salt on the TBA numbers of raw and cooked beef were determined after holding for 0 or 2 days at 4°C. Salt accelerated lipid oxidation both during cooking and subsequent storage. The α-tocopherol-coated salt also increased lipid oxidation, but only during storage after cooking. Both Tenox 4-coated salt and the mixture of BHA and BHT with salt completely inhibited lipid oxidation in cooked meat, both during cooking and upon subsequent storage. Results suggest that selected antioxidants can be used to inhibit the development of warmed-over flavor (WOF) in cooked meats.     

Evaluation of the effects of selected plant-derived nutraceuticals on the quality and shelf-life stability of raw and cooked pork sausages

The effect of lutein (200 μg/g meat), sesamol (250 μg/g meat), ellagic acid (300 μg/g meat) and olive leaf extract (200 μg/g meat) on total viable counts (TVC), pH, water holding capacity (WHC), cooking loss, lipid oxidation (thiobarbituric acid-reactive substances, TBARs), colour stability, texture and sensory evaluation of fresh and cooked pork sausages stored in aerobic or modified atmosphere packs (MAP) was investigated. Addition of sesamol, ellagic acid and olive leaf extract reduced (P < 0.001) lipid oxidation in all packaged raw and cooked pork sausages. Antioxidant potency followed the order: sesamol 250 > ellagic acid 300 > olive leaf extract 200 > lutein 200 for both raw and cooked pork sausages. Addition of sesamol increased (P < 0.001) WHC on days 2 and 12 of MAP storage. Meat addition of lutein, sesamol, ellagic acid and olive leaf extract had no detrimental effect on pH, cooking losses, TVCs, tenderness, juiciness, texture or product flavour. Lutein, sesamol, ellagic acid and olive leaf extract were effective as natural functional ingredients in suppressing lipid oxidation and have the potential to be incorporated into functional raw and cooked pork sausages.