The binding ability of alpha-lactalbumin and beta-lactoglobulin to mutagenic heterocyclic amines.

The binding ability of bovine milk proteins with mutagenic heterocyclic amines was investigated. Binding was determined with 2 mg of beta-lactoglobulin and 20 micrograms of heterocyclic amine in .4 ml of pH 7.4, 50 mM phosphate buffer, at 37 degrees C, in a shaker for 10 min. The unbound heterocyclic amine in protein-free ultrafiltrate was analyzed by HPLC method. The binding of alpha-lactalbumin, beta-lactoglobulin A and beta-lactoglobulin B were 90.44, 81.38, and 89.18%, respectively, with 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole; 37.85, 34.04, and 43.90%, respectively, with 3-amino-1-methyl-5H-pyrido[4,3-b]indole; and 49.11, 43.25, and 57.44%, respectively, with 2-amino-6-methyldipyrido[1,2-a:3',2'-d] imidazole. Binding of beta-lactoglobulin and alpha-lactalbumin to 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and 3-amino-1-methyl-5H-pyrido [4,3-b]-indole was higher at pH conditions above 7.4, and binding was lost at pH less than 5.5. Maximum binding of both proteins to 2-amino-6-methyl-dipyrido[1,2-a:3',2'-d]imidazole was at pH 7.4, and binding was inhibited at pH conditions above 8.5 and less than 6.5.     

Lack of formation of heterocyclic amines in fumes from frying French fries

The formation of heterocyclic amines (HAs) in the fumes from frying French fries in soybean oil or lard was studied. A high-pressure liquid chromatography method was used to determine the various HAs in fumes. Results showed that the yields of fumes produced from soybean oil when heated alone for 2 or 4 h were higher than from lard; however, a reversed trend was found when frying French fries in soybean oil and lard. Most fumes from soybean oil and lard while frying French fries were adsorbed onto the condensation apparatus, while the other portions were adsorbed onto the wool and glass beads, which were incorporated in our experimental design for collecting the fumes. The fumes from soybean oil when heated alone were found to contain three HAs, namely, 2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx), 2-amino-3-methylimidazo[4,5-f ]quinoline (IQ), and 1-methyl-9H-pyrido[4,3-b ]indole (Harman), whereas two more HAs, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and 3-amino-1,4-dimethyl-5H-pyrido[4,3-b ]indole (Trp-P-1), were generated in lard. Lard was more susceptible to the formation of HAs than soybean oil when both were heated alone. No HAs were detected in the fumes from French fries fried in soybean oil and lard.     

Antimutagenicity and binding of lactic acid bacteria from a Chinese cheese to mutagenic pyrolyzates

The microbiological characteristics of Nai Ge Da, a traditional cheese in China, was investigated. The lactic acid bacteria species were identified as Streptococcus cremoris, Streptococcus lactis ssp. diacetylactis, Streptococcus faecalis, and Leuconostoc paramesenteroides, Leuconostoc dextranicum, and Leuconostoc mesenteroides. Streptococcus cremoris, and Leuconostoc paramesenteroides were the dominant strains. The antimutagenicities and binding of strains of S. cremoris and S. lactic ssp. diacetylactis to mutagenic pyrolyzates was investigated. The lyophilized cells of strains showed the highest inhibitory effect on the 3-amino-1,4-dimethyl-[5H]pyrido[4,3-b] indol (Trp-P-1) and 3-amino-1-methyl-[5H]pyrido[4,3-b] indol (Trp-P-2), but many strains had no significant inhibition against 2-amino-6-methyldipyrido[1,2-a:3',2'-d] imidazole (Glu-P-1). The Trp-P-1 and Trp-P-2 were effectively bound to all bacterial cells, but binding of Glu-P-1 to cells was not effective. Among the strains tested, S. cremoris C-25 not only indicated highest binding to Trp-P-1 and Trp-P-2, but it also it had a 25.36% binding ability with Glu-P-1. When all strains were autoclaved for 15 min at 120 degrees C, binding ability to mutagens was reduced by 3 to 19%. The decrease of binding ability of S. cremoris C-25 was much less, being only 2%. After heating at 80 degrees C for 3 h, the binding ability of all strains to mutagenic pyrolyzates was not much different from those of parent viable cells.     

Binding of heterocyclic amines by yeast cells and their fractions

The binding of mutagenic pyrolysis products to cells of 50 yeast strains and their cell fractions was investigated. Cells of all yeast strains effectively bound 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). Cell walls (CW), and cell wall glucan and mannan (5 mg in each case) showed the highest binding of Trp-P-1 (50 μg ml^?1); glucan adsorbed virtually all of the Trp-P-1. Cytoplasm also showed some binding but was much less effective. Glucans also bound well with 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo 4,5-quinoxaline (MeIQX) much more than CW, but 2-amino-5-phenylpyridine (Phe-P-1) and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MelQ) were not effectively bound. The quantity of IQ, MeIQ, Phe-P-1 and MeIQX bound was dependent on the strain of yeast. The mutagenic pyrolysis products bound to cells were effectively extracted by aqueous methanol, ammonia (50 g litre^?1) and alcohol, but not by water. The binding was pH dependent and inhibited by metal salts. When yeast cells were heated to 100° for 15 min, the binding of Trp-P-1 decreased by about 30% but Saccharomyces cerevisiae 50 heated to 100° did not differ much from untreated cells in its binding ability.     

PURIFICATION AND PROPERTIES OF DESMUTAGENIC FACTOR FROM BROCCOLI (BRASSICA OLERANCEA VAR. ITALICA PLENCK) FOR MUTAGENIC PRINCIPLE OF TRYPTOPHAN PYROLYSATE

A desmutagenic factor which inhibited the mutagenicity of the mutagens, Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole), Trp-P-2 (3-amino-1-methyl)-5H-pyrido[4,3-b]indole), ethidiumbromide and 2-aminoanthracene, was purified from broccoli (Brassica olerancea var. italica plenck). The factor was not sedimented by ultra-centrifugation at 200,000 xg for 2 h. It adsorbed to a DEAE-cellulose column and was eluted with low concentration of potassium chloride. The purified factor exhibited a heme-like protein absorption spectrum with a Soret band at 403 nm and α and β bands at 640 and 504 nm, respectively. The molecualr weight was estimated to be approximately 53,000 by SDS-gel electrophoresis.     

Binding of mutagens by fractions of the cell wall skeleton of lactic acid bacteria on mutagens

The binding effect of cells and cell fractions, cell wall skeleton, cytoplasm, whole cells, and cell wall skeleton treated by lysozyme and alpha-amylase at 37 degrees C for 5 h, on Trp-P-1 (3-amino-1,4-dimethyl-[5H]pyrido [4,3-b]indole) and Trp-P-2 (3-amino-1-methyl-[5H]-pyrido[4,3-b]indole) were investigated. The cell and cell wall skeleton of Streptococcus cremoris Z-25 had greater binding activity, but cytoplasm and extract of cell wall skeleton did not bind Trp-P-1 and Trp-P-2. When the cells or cell wall skeleton were treated with lysozyme and alpha-amylase, unbound Trp-P-1 and Trp-P-2 concentrations were greater than that of the untreated control. It is possible that cell walls may be involved in the binding of mutagenic pyrolyzates to lactic acid bacteria. The cell wall skeleton of S. cremoris Z-25, Lactobacillus acidophilus IFO 13951, and Bifidobacterium bifidum IFO 14252 showed binding of Trp-P-1, 2-amino-6-methyldipyrido(1,2-a:3',2'- d)imidazole, 2-amino-5-phenylpyridine, 2-amino-3-methylimidazo(4,5-f)quinoline, 2-amino-3,4-dimethylimidazo(4,5-f) quinoline, and 2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline. The cell wall skeleton of S. cremoris group and Streptococcus lactis also showed the binding activity with A N-nitrosodimethylamine. The binding of Trp-P-1 to cell walls was very high, and the binding of mutagenic pyrolyzates was variable with different bacterial species. The peptidoglycan complex and polysaccharides liberated from cell wall skeleton of S. cremoris Z-25 showed strong binding of Trp-P-2. Peptidoglycans has a binding effect of about 19.86 micrograms/mg; polysaccharides had a binding effect of 14 micrograms/mg.     

Effects of various additives on the formation of heterocyclic amines in fried fish fibre

The effects of various additives on the formation of heterocyclic amines (HAs) in fried fish fibre (Trachinooephlus myops) were studied. Fried fish fibre was prepared by boiling raw snake fish, followed by deboning, eviscerating, separating of fish meat and pressing. The fish meat was subjected to frying, during which treatment the additives, such as sugar, monosodium glutamate (MSG), antioxidants and edible oil, were added. The HAs were analyzed by high-performance liquid chromatography (HPLC) with diode-array detection. Results showed that the formation of HAs was retarded after the addition of a high level of sugar (19%), and the amount of 9H-pyrido-[4,3-b]indole (Norharman), 1-methyl-9H-pyrido-[4,3-b]indole (Harman), 2-amino-9H-pyrido[2,3-b]indole (AαC) or 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC) also decreased to a minimum. The total amount of HAs rose with increasing levels of MSG, and the individual HAs, Norharman, Harman, AαC and MeAαC showed the same trend. Antioxidants, such as vitamin C, α-tocopherol and BHT (Butylated hydroxytoluene), did not show any consistent effect of concentration on HAs formation. Coconut oil contributed to the highest levels of HAs formation, followed by lard and soybean oil.     

植物多酚抑制热加工肉制品中杂环胺形成机制研究进展

杂环胺（heterocyclic amines,HAs）是肉制品热加工过程中产生的一类具有极强致畸致癌活性的有毒化合物,其中2-氨基-3-甲基咪唑并[4,5-f]喹啉（2-amino-3-methyl-imidazo[4,5-f]-quinoline,IQ）和2-氨基-3,4-二甲基咪唑并[4,5-f]喹啉（2-amino-3,4-dimethyl-imidazo[4,5-f]-quinoline,MeIQ）,2-氨基-1-甲基-6-苯基咪唑并[4,5-b]吡啶（2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine,PhIP）,1-甲基-9H-吡啶并[3,4-b]吲哚（1-methyl-9Hpyrido[3,4-b]indole,Harman）和9H-吡啶并[3,4-b]吲哚（9H-pyrido[3,4-b]indole,Norharman）3类HAs在热加工肉制品中较为常见且分布广泛。本文即围绕上述3类HAs,简要分析其形成的途径及机制,并详细阐述外源添加植物多酚抑制HAs形成的作用机制,最后依据现有研究归纳总结出多酚化合物抑制HAs与其化...     

3种熏烤鸡肉制品中杂环胺含量的检测与比较

目的 以3种熏烤鸡肉制品(鸡胗、鸡翅、鸡爪)为研究对象, 通过高效液相色谱测定其中5种杂环胺类物质(heterocyclic aromatic amines, HAAs), 即2-氨基-3-甲基咪唑并[4,5-f]喹啉(2-Amino-3- methylimidazo(4,5-f)quinoline, IQ)、2-氨基-1-甲基-6-苯基-咪唑并[4,5-b]吡啶(2-Amino-1-methyl- 6-phenylimidazo(4,5-b)pyridine, PhIP)、9H-吡啶并[4,3-b]吲哚(9H-pyrido[4,3-b]indole, Norharman)、1-甲基-9H-吡啶并[4,3-b]吲哚(1-methyl-9H-pyrido[4,3-b]indol, Harman)、2-氨基-9H-吡啶并[2,3-b]吲哚(2-amine-9H-pyrido[2,3-b]indol, AaC)的含量并进行比较。方法 采用二元流动相乙腈/醋酸-醋酸铵(pH=3.4)进行梯度洗脱, 其中乙腈/醋酸-醋酸铵随时间配比为: 0 min: 10%/90%; 10 min: 20%/80%; 25 min: 50%/50%; 35 min: 10%/90%。紫外检测波长263 nm; 荧光激发波长/发射波长随时间改变为0 min: 300/440 nm; 17 min: 315/390 nm; 21 min: 335/410 nm。结果 在3种鸡肉熏烤制品中提取的5种杂环胺类物质中, PhIP的含量最高, 且在鸡胗中最为显著, 高达152.38 ng/g, 工业化生产的鸡胗中PhIP含量仅为4.23 ng/g; 各产品中Harman的含量最低, 且在鸡爪产品及工业化生产的鸡翅产品中未检出; 熏烤的鸡肉制品中提取的IQ、PhIP、Norharman、Harman、AaC的含量均高于工业化产品。结论 工业化生产的鸡胗、鸡翅、鸡爪中的5种HAAs的含量均低于3家传统熏烤产品的含量, 传统熏烤条件下鸡肉制品的食用安全系数相对较低, 工业化产品的安全性相对较高。     

花椒叶提取物对烤牛肉饼杂环胺形成的影响

以牛肉和花椒叶为研究对象,研究花椒叶提取物（Zanthoxylum bungeanum Maxim. leaf extract,ZME）添加量（0.015%、0.030%、0.045%）对烤牛肉饼中杂环胺（heterocyclic amines,HAs）形成的影响。结果表明,与对照组相比,ZME能够显著抑制烤牛肉饼中总HAs的形成（P＜0.05）,对其最大抑制率为39.87%,但对不同种类HAs形成的影响不同。其中,添加0.045% ZME对2-氨基-1-甲基-6-苯基咪唑并[4,5-b]吡啶、2-氨基-3-甲基咪唑并[4,5-f]喹啉、2-氨基-3,4-二甲基咪唑并[4,5-f]喹啉、1-甲基-9H-吡啶并[3,4-b]吲哚和2-氨基-9H-吡啶并[2,3-b]吲哚的抑制率分别达到71.76%、78.02%、49.07%、35.82%和100%;而0.045% ZME却促进2-氨基-3,8-二甲基咪唑并[4,5-f]喹喔啉和9H-吡啶并[3,4-b]吲哚的形成。进一步分析ZME对烤牛肉饼中HAs前体物的影响,结果显示前体物的消耗随着ZME添加量的增加呈降低趋势,相关性分析表明HAs的形成与多种游离氨基酸的消耗显著相关。上述结果表明ZME能显著抑制烤牛肉饼中HAs的形成,为其提高加工食品安全性及更广泛的应用提供理论依据。     

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。     

Formation of heterocyclic amines in fried fish fiber during processing and storage

The formation of heterocyclic amines (HAs) in fried fish fiber during processing and storage was studied. Fried fish fiber was prepared by boiling of raw fish, followed by eviscerating, pressing, chopping, and then the fish meat was subjected to frying, during which the various additives such as sugar, soybean sauce, and edible oil were added. The various HAs in fried fish fiber were analyzed by high-performance liquid chromatography with photodiode-array detection. Only four HAs, Norharman, Harman, 2-amino-9H-pyrido[2,3-b]indole, and 2-amino-3-methyl-9H-pyrido[2,3-b]indole were detected in fried fish fiber. The amount of HAs increased with increasing frying temperature. Amino acids might play a more important role for HA formation than reducing sugar during processing of fried fish fiber. During storage, the HAs increased with increasing storage temperature when the fried fish fiber was packed in an aluminum foil bag. However, the relationship between storage temperature and HAs formation was not consistent when the fried fish fiber was packed in a plastic bag.     

Variation in milk protein concentrations associated with genetic polymorphism and environmental factors

Concentrations of alpha s-casein, beta-casein, kappa-casein, beta-lactoglobulin, alpha-lactalbumin, serum albumin, and immunoglobulin in milk from 1888 Holstein cows were determined monthly over the lactation period. Cows were phenotyped for genetic variants of alpha s1-casein, beta-casein, kappa-casein, and beta-lactoglobulin. Least squares analyses showed variations in individual proteins due to parity number, month of test, stage of lactation, somatic cell count, fat content, milk yield, and phenotypes of cows for milk proteins. beta-Casein declined and serum proteins increased with advancing age of cows. Concentration of individual proteins decreased during the first 2 to 3 mo in lactation and then increased as lactation progressed. alpha s1-Casein variants significantly affected concentrations of alpha s-casein (BC greater than BB greater than AB) and beta-lactoglobulin (AB greater than BB greater than BC). Variant B for beta-casein is associated with lower alpha s-casein, beta-lactoglobulin, immunoglobulins, and higher beta-casein and alpha-lactalbumin concentrations than variant A1, A2, or A3. Milk from BB kappa-casein, and BB beta-lactoglobulin cows contained more alpha s-casein, kappa-casein, and less beta-lactoglobulin than milk from AA cows for the two proteins. Concentrations of all proteins were negatively correlated with milk production. Increased somatic cell counts were associated with lower beta-casein and higher concentrations of other proteins. Fat content of milk was positively correlated with the three casein fractions and beta-lactoglobulin.     

Environmental factors affecting plasmin activity in milk

A total of 367 milk samples were collected from 43 individual Holstein cows during 1 yr. Samples were analyzed for plasmin activity, total casein, alpha s-casein (alpha s1-casein + alpha s2-casein), beta-casein, kappa-casein, and SCC. Least squares analyses showed that SCC in milk were positively related (r = .62) to plasmin activity. An increase of SCC from 100,000 to 1,300,000/ml was associated with a 2.3-fold increase in plasmin activity (100 vs. 230 x 10(-6) units/ml). Increased plasmin activity was associated with advancing stage of lactation and older cows after appropriate adjustments were made for the effects of milk yield and SCC. Milk samples obtained in fall and winter were higher, but not significantly, in plasmin activity. Plasmin activity was also associated with major casein components and milk pH. Correlations coefficients between plasmin and alpha s-casein, beta-casein, and pH were -.14, -.27, and .19.     

Formation of heterocyclic amines in a model system during heating

The formation of heterocyclic amines (HAs) in a model system during heating at 100, 150, or 200 degrees C for varied lengths of time was studied. The following systems were used: (i) phenylalanine, (ii) creatinine, (iii) phenylalanine and glucose, (iv) phenylalanine and creatinine, (v) glucose and creatinine, and (vi) phenylalanine, glucose, and creatinine. Results showed that HAs could only be found in both systems of glucose and creatinine, and of phenylalanine, glucose, and creatinine. Both 2-amino-9H-pyrido-[2,3-b]indole (AalphaC) and 2-amino-3-methyl-9H-pyrido-[2,3-b]indole (MeAalphaC) were observed in the former system, and the formation rate of AalphaC was higher than MeAalphaC. For the latter system, 2-amino-3-dimethylimidazo[4,5-f]quinoxaline (IQx), 9H-pyrido-[4,3-b]indole (Norharman), 1-methyl-9H-pyrido-[4,3-b]indole (Harman), AalphaC, and MeAalphaC were present. The formation rate of AalphaC was the highest at 200 degrees C, followed by MeAalphaC, Harman, Norharman, and IQx. In addition, the varieties of HAs increased both with increasing heating time and temperature. The amounts of HAs formed were less in the model system of glucose and creatinine than that of phenylalanine, glucose, and creatinine. The same trend was also observed for the formation rate of HAs. At 150 or 200 degrees C, the amounts of IQx, Harman, Norharman, AalphaC, and MeAalphaC increased in the initial period of heating and then reached a plateau. The results of this study provided a basic understanding of the conditions that result in the formation of HAs during cooking of meat and fish products.     

Two food-borne heterocyclic amines: metabolism and DNA adduct formation of amino-alpha-carbolines

The amino-alpha-carbolines 2-amino-9H-pyrido[2,3-b]indole (AalphaC) and 2-amino-3-methyl-9H-pyrido-[2,3-b]indole (MeAalphaC) are two mutagenic and carcinogenic heterocyclic amines formed during ordinary cooking. Amino-alpha-carbolines can be formed in model systems by pyrolyzing tryptophan or proteins of animal or vegetable origin, furthermore they are found in many cooked foods, such as fish, meat, and chicken. The specific mutagenicity of the amino-alpha-carbolines are lower in the Ames Salmonella assay than other heterocyclic amines, but in rodent studies the carcinogenicity of the amino-alpha-carbolines are comparable to other heterocyclic amines. The metabolic pathways of the amino-alpha-carbolines have been studied in vitro and in vivo, and the detoxified phase I and phase II metabolites characterized and quantified. The metabolic activation of the amino-alpha-carbolines and the formation of DNA-adducts have also been studied. Characteristic for the amino-alpha-carbolines are that relatively large amounts of these compounds in rat and human hepatic microsomes are activated to potent carcinogenic compounds compared with other heterocyclic amines, but further in vivo studies of the amino-alpha-carbolines are needed to highlight these indications. In this review, the main characteristics with focus on the metabolism and the DNA-adduct formation of the amino-alpha-carbolines are described and compared with other heterocyclic amines.     

Influence of fructooligosaccharides and garlic on formation of heterocyclic amines in fried ground beef patties

The effects of fructooligosaccharide (FOS) and garlic on the formation of 15 heterocyclic amines (HCAs) were evaluated in fried beef patties. The HCAs were extracted from the fried meat samples and purified using a solid-phase extraction method and then analyzed on a liquid chromatography-mass spectrometry. Among the 15 HCAs, 3-amino-1, 4-dimethyl-5H-pyrido-[4,3-b]indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido [4,3-b]indole (Trp-P-2), 2-amino-6-methyldipyrido [1,2-a:3′,2′-d]imidazole (Glu-P-1), 2-aminodipyrido [1,2-a:3′,2′-d]imidazole (Glu-P-2), 9H-pyrido [3,4-b]indole (norharman), 1-methyl-9H-pyrido [3,4-b]indole (harman), 2-amino-9H-pyrido [2,3-b]indole (AαC), 2-amino-3,8 dimethylimidazo [4,5-f]-quinoxaline (MeIQx), and 2-amino-1-methyl-6-phenylimidazo [4,5-b]-pyridine (PhIP) were detected in all of the cooked beef patties. Analysis of variance revealed that the addition of 1 or 3 g of FOS significantly reduced the formation of total amino-carboline type HCAs in the cooked beef patties, and adding the 1 or 3 g of FOS to ground beef patties reduced levels of PhIP and MeIQx (amino-imidazo-azaarenes; AIAs) in the patties. When it is compared with the HCA formation in control, additions of minced garlic (5.0, 10.0, and 15.0 g) to the ground beef patties (100 g) reduced HCA formation in the range of 14 to 100%.     

Preconcentration and Simultaneous Determination of Heterocyclic Aromatic Amines in Grilled Pork Samples by Ion-Pair-Based Surfactant-Assisted Dispersive Liquid-Liquid Microextraction and High-Performance Liquid Chromatography

An effective ion-pair-based surfactant-assisted dispersive liquid-liquid microextraction combined with high-performance liquid chromatography (HPLC) has been evaluated for the extraction and preconcentration of four heterocyclic aromatic amines (i.e., 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQ); 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx); 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP); and 1-methyl-9H-pyrido[3,4-B]indole (Harmane)). In the extraction method, sodium dodecyl sulfate (SDS) was used as both ion-pairing and disperser agent and 1-octanol was selected as extraction solvent. The effects of various parameters on the extraction efficiency such as kind and concentration of surfactant, kind and volume of extraction, salt addition, vortex extraction, and centrifugation time were investigated. Under the selected condition, the method provided high enrichment factor in the ranged of 124–145. Good linearity was 0.01–1000 μg kg^?1 with the correlation coefficient (R ²)?>?0.999. The limit of detection was 0.01 μg kg^?1 for all compounds. The matrix match calibration was used for quantitation of the target analytes in grilled pork samples. The proposed method was successfully applied to analysis of heterocyclic aromatic amines in grilled pork samples where good recoveries were obtained in the range of 90 and 106 %.     

Effects of traditional chinese cooking methods on formation of heterocyclic aromatic amines in lamb patties

Different amounts of the potent mutagenic and/or carcinogenic heterocyclic aromatic amines (HAAs) are formed in muscle-based foods under different cooking methods. HAAs (9 varieties) in lamb patties cooked using traditional Chinese cooking methods (roasting, frying, panfrying, and stewing in seasonings) were investigated. The total HAAs contents in roasted, fried, pan-fried, and stewed patties were 4.39-123.15 ng/g, 3.59-43.24 ng/g, 0.71-10.05 ng/g, and 51.07-120.32 ng/g, respectively. Amounts of HAAs increased as cooking time increased. 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) was the dominant HAAs in deep roasted and fried samples, while 1-methyl- 9H-pyrido [3,4-b] indole (Harman) and 9H-pyrido [3,4-b] indole (Norharman) were the main HAAs in pan-fried and stewed samples. Types and contents of HAAs formed at different cooking times using different methods are unique. Stewing in seasoning generated a higher HAAs content than the high-temperature cooking methods roasting, frying, and pan-frying.     

Studies on antimutagenic effect of milk cultured with lactic acid bacteria on the Trp-P2-induced mutagenicity to TA98 strain of Salmonella typhimurium.

The inhibitory effects of cultured milk using 76 strains of lactic acid bacteria isolated from milk products were investigated on the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P2), a tryptophan pyrolysate for Salmonella typhimurium TA98. Each cultured milk sample displayed its characteristic antimutagenic effect against the mutagenicity of Trp-P2. The milk cultured with Lactobacillus acidophilus LA106 (LA2) showed the highest inhibition of 82.1% among the strains used. Milk samples cultured with Lactococcus lactis subsp. lactis, Lll103 (10-3) and Lll102 (KM) also exhibited higher inhibition percentages.