2-(Hydroxymethyl)-N-nitrosothiazolidine-4-carboxylic Acid in Smoked Meats and Bacon and Conversion to 2-(Hydroxymethyl)-N-Nitrosothiazolidine During High-Heat Cooking

Concentrations of 2-(hydroxymethyl)-N-nitrosothiazolidine-4-carbox-ylic acid (HMNTCA) in a variety of smoked meats and bacon were determined by a newly developed method based on derivatization of HMNTCA with diazomethane and analysis by high performance liquid chromatography-thermal energy analyzer. Of samples analyzed, 4/8 raw bacon, 6/8 fried bacon, and 7/14 miscellaneous cured meat products contained 10–540 ppb of HMNTCA. Evidence suggested 2-(hydroxyrnethyl)-N-nitrosofhiazolidine in fried bacon likely originated by heat-induced decarboxylation of HMNTCA. Identity of HMNTCA in selected samples was confirmed by mass spectrometry.     

Polycyclic aromatic hydrocarbons in smoked cheese

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) represent a group of organic compounds containing two or more aromatic rings. Their control in the human food chain is required due to the mutagenic and carcinogenic potential, exhibited in vertebrates. In the present study, the occurrence of PAHs in 36 cheeses smoked by various processes was investigated. RESULTS: PAH concentrations (sum of 15 US EPA PAHs) found in samples smoked under controlled industrial conditions were at level 0.11 µg kg^?1, whereas in ‘home‐made’ cheeses, the PAH content was up to 10 times higher. A similar trend was observed for B[a]P, a marker compound representing carcinogenic PAHs. While its levels in commercial products prepared by controlled smoking technologies were close to the limit of quantification (0.03 µg kg^?1); in household samples, the B[a]P content ranged from 0.6 to 0.9 µg kg^?1. Significantly higher amounts of PAHs (up to three to six times) were found in surface layers as compared to internal parts of cheese. CONCLUSION: Although smoked cheese is a popular food, only several papers have focused on PAH levels in these products. This paper evaluates the contribution of different smoking technologies to PAH contamination of several cheeses and thus can help in a risk assessment associated with their consumption. Moreover, the study shows the concentration ratios of selected PAHs, from which the type of smoking technology can be indicated. The results obtained in this study also supported the suggestion of the EU Scientific Committee on Food to use benzo[a]pyrene as an indicator of the occurrence of higher‐molecular mass PAHs. Copyright © 2008 Society of Chemical Industry     

ε-(γ-Glutamyl)lysine Crosslink Distribution in Foods as Determined by Improved Method

Quantitative analysis of ε-(γ-glutamyl)lysine crosslink in 127 foods was achieved with a, preliminary separation by reverse phase-HPLC before o-phthalaldehyde derivatization to remove interfering peaks. ε-(γ-Glutamyl)lysine was detected in 96 foods and its contents ranged from 0.2 to 135 μmol/lOOg protein. High levels were found in fish paste products, processed fish, shellfish, meats and soybeans, and raw poultry organs. For fish and meats, the level of ε-(γ-glutamyl)lysine in processed foods and fish paste was relatively higher than that in raw materials. The improved procedure could be applied for screening materials with transglutaminase activities.     

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.     

Literature compilation of volatile N-nitrosamines in processed meat and poultry products - an update

ABSTRACT

A compilation of volatile N-nitrosamine levels in processed (e.g., cured, canned, smoked) meat and poultry products is presented. Over 1800 samples of processed meat products including bacon, ham, salami, sausage, and various other processed meat and poultry products have been examined for the presence of eight volatile N-nitrosamines. The database compiled from the literature is based on 25 references published for the period of 1985 to 2018 from 14 countries. N-nitrosodimethylamine (NDMA), N-nitrosopiperidine (NPIP), and N-nitrosopyrrolidine (NPYR), are the most frequently identified volatile N-nitrosamines occurring in processed meat and poultry products. N-nitrosodiethylamine (NDEA), and N-nitrosodibutylamine (NDBA) are also frequently observed to a lesser extent. The processed meat and poultry products with the highest levels of volatile N-nitrosamines were pork (fried, fat only eaten), poultry (fried), poultry (spiced, grilled), and bacon (fried).     

Effect of pre‐treatment and smoking process (cold and hot) on chemical,microbiological and sensory quality of mackerel (Scomber scombrus)

The sensory, hygienic, toxicological and nutritional profiles of hot‐ and cold‐smoked mackerel samples were studied with various pre‐treatments. The panellists assessed all smoked samples as barely to quite acceptable products whilst the product immersed in 120 g kg^?1 sodium chloride and 60 g kg^?1 fructose prior to smoking was assessed as very acceptable regarding its sensory characteristics. The available lysine in all hot smoked samples was reduced to the same extent (32%) whilst a very good correlation (r = 0.912) was observed between loss of available lysine and colour formation of the cold‐smoked products, indicating the high contribution of lysine in the interactions with carbonyls. Histamine was found in highly unacceptable levels even in the unprocessed samples (600 mg kg^?1) and strongly increased (2220 and 2250 mg kg^?1) in the cold‐ and hot‐smoked samples, respectively, due to all treatments. These are levels which would be expected to cause symptoms of scombrotoxin poisoning. Benzo(a)pyrene, fluoranthene and perylene were at high levels both in cold‐ (2.1, 4.3 ± 0.04 and 7.2 ± 0.05 µg kg^?1) and hot‐smoked samples (9.2, 7.8 ± 0.03 and 9.4 ± 0.14 µg kg^?1, respectively) and were, as expected, influenced by the temperature. The aerobic bacteria remained at acceptable levels, since salt and high temperature prevent bacterial growth. Copyright © 2004 Society of Chemical Industry     

Chemical and biochemical study of industrially produced San Simón da Costa smoked semi-hard cow's milk cheeses: Effects of storage under vacuum and different modified atmospheres

Two batches of smoked, semi-hard (ripened for 45 d) San Simón da Costa cow's milk cheeses with Protected Designation of Origin were used to investigate the chemical, biochemical, and sensorial parameters that may be affected by modified-atmosphere packaging. Cheeses were packaged for 45 d as follows: vacuum packaging, packaging in 100% N₂, packaging in a gas mixture of 20% CO₂/80% N₂, and packaging in a gas mixture of 50% CO₂/50% N₂. The San Simón da Costa cheeses were characterized by high contents of lactic, oxalic, and citric organic acids. The main free amino acids found were isoleucine, phenylalanine, serine, valine, lysine, and glutamic acid, and the most abundant volatile compounds included ethanol, diacetyl, 2-butanol, isopropyl alcohol, furfural, acetaldehyde, 2-butanone, acetone, and 2-methylfuran. Modified atmospheres appeared to alter the ripening processes by affecting lipolysis, as indicated by the lower concentrations of butyric and propionic acids compared with control cheeses. In addition, modified-atmosphere packaging altered the proteolysis processes, yielding higher amounts of branched-chain alcohols. The results revealed that storage under modified atmosphere contributes to the accumulation of several compounds probably derived from smoke, including aldehydes such as 2-furancarboxaldehyde (furfural), alcohols such as 2-methoxyphenol (guaiacol), ketones such as 2-cyclopenten-1-one, and esters such as methyl furancarboxylate, which were negatively correlated with flavor. Vacuum packaging was the most useful technique in terms of preserving the sensory quality of San Simón da Costa Protected Designation of Origin cheeses. Considering the current demands for packaged portions of food at the distribution and retail levels and the potential health risks associated with some smoke-derived compounds usually present in some smoked foods, the results obtained in this study may be of special interest to the cheese industry.     

Influence of smoking parameters on the concentration of polycyclic aromatic hydrocarbons (PAHs) in Danish smoked fish

A new method for the analysis of 25 polycyclic aromatic hydrocarbon (PAH) compounds in fish was developed, validated, and used for the quantification of PAHs in 180 industrially smoked fish products. The method included pressurized liquid extraction, gel-permeation chromatography (Bio-beads S-X3), solid-phase extraction (silica gel), and gas chromatography-mass spectrometry analysis. The sum concentration of 25 PAHs (∑PAH₂₅) was highest in smoked herring (n = 3) and mackerel fillets (n = 13), with an average concentration of 320 and 235 µg kg^?1, respectively. Lowest average ∑PAH₂₅ concentrations were obtained for indirectly smoked trout (26 µg kg^?1). Principal component analysis was used to correlate processing parameters to PAH concentrations and to identify the effects of these parameters. The analysis showed that for salmon hot-smoking conditions lead to higher ΣPAH₂₅ than cold smoking, and for other fish species direct smoking leads to higher ΣPAH₂₅ than indirect smoking. Also, the usage of common alder increases the PAH contamination compared with beech. The effects of smoking time, combustion temperatures, and two types of smoke-generating material on the ∑PAH₂₅ were also tested in a pilot plant study with smoked trout as a model fish. In addition to confirming that increased combustion temperatures and usage of common alder in comparison with beech increased ∑PAH₂₅, it was also revealed that the PAH concentration decreased in the order fish skin ? outer layer of the fish muscle > inner part of the fish muscle.     

What do we think we eat? Single tracing method across foodstuff of animal origin found in Greek market

In this study, analysis of 348 food products was performed based on a universal 16S rDNA marker. The purpose was to check whether the content of the product in particular species listed on the label corresponded with the actual composition of the product. All products were purchased from the local market and from national and international super-market chains and included dairy products and industrially processed packaged food from meat, poultry and fish. All products were grouped in seven groups: milk, food for pets, packaged yellow cheeses, packaged white cheeses, PDO cheeses, processed meats and frozen fish foodstuff. Mislabelled foods were found in all seven groups but the extent of adulteration differed between groups. The lowest percentage (15%) was found for packaged yellow cheeses whilst the highest (54%) for foods for pets. Mislabelling for milks was 26%, for packaged white cheeses 29%, for PDO cheeses 26%, for frozen fish products 35% and for processed meats 34%. These alarming findings, combined with those retrieved from the literature, raise significant concern in the monitoring methods employed for supervision worldwide. It is urgent for the authorities to address the adequacy of labelling, to improve and extent monitoring methods and redefine penalising policies against food fraud. On the other hand, the food industry should assume its responsibilities and establish its own accurate and extensive control and inspection mechanisms. Otherwise, there is a growing risk of losing the trust of consumers as well as a large percentage of profits.     

Dioxins,furans and non-ortho-PCBs in Canadian total diet foods 1992–1999 and 1985–1988

In the period from 1985 to 1999, about 600 samples of total diet foods from Canadian cites were analysed for dioxins, furans and non-ortho-PCBs. Toxic equivalent (TEQ) concentrations on a lipid basis were found to be the highest in dairy and beef products followed by poultry and pork. These levels decreased over the 15-year period of sampling, particularly those for fluid milk, less so for poultry and pork and little or no change for beef. Calculation of the human daily intake for the years 1985–1988 showed values a little less than 1?pg of TEQ₂₀₀₅ polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran per kg body weight, falling progressively to less than 0.5?pg of TEQ in 1999. These estimates are lower than the 2.3?pg of TEQ currently recommended by the WHO. The main categories of foods contributing to the TEQ were animal meats and dairy products, with lesser amounts from fish and other foods.     

N-NITROSOPROLINE AND N-NITROSOSARCOSINE IN ESTONIAN FOODSTUFFS

The N-nitrosoamino acids (NNA) N-nitrosoproline (NPRO) and N-nitrososarcosine (NSAR) are precursors of the carcinogenic N-nitrosamines. Methodology using gas chromatography for their determination and data on their contents in 52 food products are presented. Food products consisted of smoked meats (12), smoked (9) and boiled (11) sausage, cheese (10), fish (7) and beer (3). Results showed that NNA formed during processing, particularly in meat, where levels of NPRO were as high as 353μg/kg. The compounds accumulated in the adipose tissue and surface portion of the product. Smoking caused increased formation of NPRO, while the use of liquid smoke minimized it. NPRO in meat products in natural casings was higher than in synthetic ones, and frying of boiled sausage and hams further enchanced NPRO formation. Like meat, smoked cheese and fish showed consistently higher NNA levels than the non-smoked products. These data indicate means of reducing NNA contents in foods by modification of processing techniques .     

Polycyclic aromatic hydrocarbons in traditionally smoked meat products from the Baltic states

A total of 77 traditionally smoked meat samples produced in Latvia, Lithuania, and Estonia were tested for the occurrence of four EU regulated polycyclic aromatic hydrocarbons (PAHs). Levels of PAHs exceeding the EU maximum levels for benzo[a]pyrene and for the sum of four PAHs (PAH4) were detected in 46% and 48% of the samples originating from Latvia. The detected BaP levels in smoked meats ranged from 0.05 to 166 μg kg^?1, while the PAH4 content ranged from 0.42 to 628 μg kg^?1. The mean dietary exposure to PAHs was estimated at the levels of 5.4 ng BaP/kg bw/day and 36 ng PAH4/kg bw/day. The margin of exposure (MOE) approach was utilised to assess the risks to Latvian consumers due to PAHs and the obtained MOEs were in a range of 7205–24,434, thus indicating a potential concern for consumer health for specific population groups.     

Reactive dicarbonyl compounds and 5-(hydroxymethyl)-2-furfural in carbonated beverages containing high fructose corn syrup

α-Dicarbonyl compounds, namely glyoxal (GO), methylglyoxal (MGO) and 3-deoxyglucosone (3-DOG), as well as 5-(hydroxymethyl)-2-furfural (5-HMF) were found and measured in carbonated soft drinks (CSD). It was realized that high fructose corn syrup (HFCS) in regular CSDs was the major source of α-dicarbonyl compounds in beverages after comparison of levels in regular and diet CSDs. In two most commonly used HFCS formulas, 42% and 55% HFCS, the highest level of dicarbonyl found was 3-DOG, followed by MGO, and then GO. The stability of dicarbonyls in CSDs containing HFCS and (−)-epigallocatechin gallate (EGCG) which were incubated at 35 and 45 °C was investigated. It was found that EGCG decreased from 1 mg/mL to 0.5 and 0.3 mg/mL for 35 and 45 °C, respectively, in 16 days storage. Moreover, the reactions of EGCG with MGO, 3-DOG and 5-HMF were observed from the comparison of storage CSDs with and without EGCG under acidic conditions.     

Rapid determination of benzo(a)pyrene in processed meat and fish samples by second-derivative constant-energy synchronous fluorescence spectrometry

A simple, rapid and cost-effective method has been established for the determination of the quantity of benzo(a)pyrene (BaP), one of the most carcinogenic polycyclic aromatic hydrocarbons (PAHs), in roasted, smoked and charcoal grilled foods. Second-derivative constant-energy synchronous fluorescence spectrometry (DCESFS) improves the spectral resolution and selectivity of the fluorescence method. By using this method, processed meat, fish and some other food samples were analysed without resorting to complex pre-separation and purification procedures. The method was found to have a recovery of 97.7%?±?4.3%. The limit of detection (LOD) for BaP was 0.14?µg?kg^–1, far below the regulatory limit (1.0?µg?kg^–1) for BaP in food samples specified by the European Union. A certified reference material (Coconut oil, BCR®-458) was used to confirm the validity of the proposed method. The results suggest that the measurements are in a good agreement with the certified BaP concentrations (5.4% deviation). The results obtained by the proposed method for analysing BaP in food samples correlated well with those obtained by GC/MS.     

Identification of aroma-active compounds in Cheddar cheese imparted by wood smoke

Cheddar cheese is the most popular cheese in the United States, and the demand for specialty categories of cheese, such as smoked cheese, are rising. The objective of this study was to characterize the flavor differences among Cheddar cheeses smoked with hickory, cherry, or apple woods, and to identify important aroma-active compounds contributing to these differences. First, the aroma-active compound profiles of hickory, cherry, and apple wood smokes were analyzed by solid-phase microextraction (SPME) gas chromatography-olfactometry (GCO) and gas chromatography-mass spectrometry (GC-MS). Subsequently, commercial Cheddar cheeses smoked with hickory, cherry, or apple woods, as well as an unsmoked control, were evaluated by a trained sensory panel and by SPME GCO and GC-MS to identify aroma-active compounds. Selected compounds were quantified with external standard curves. Seventy-eight aroma-active compounds were identified in wood smokes. Compounds included phenolics, carbonyls, and furans. The trained panel identified distinct sensory attributes and intensities among the 3 cheeses exposed to different wood smokes (P < 0.05). Hickory smoked cheeses had the highest intensities of flavors associated with characteristic “smokiness” including smoke aroma, overall smoke flavor intensity, and meaty, smoky flavor. Cherry wood smoked cheeses were distinguished by the presence of a fruity flavor. Apple wood smoked cheeses were characterized by the presence of a waxy, green flavor. Ninety-nine aroma-active compounds were identified in smoked cheeses. Phenol, guaiacol, 4-methylguaiacol, and syringol were identified as the most important compounds contributing to characteristic “smokiness.” Benzyl alcohol contributed to the fruity flavor in cherry wood smoked cheeses, and 2-methyl-2-butenal and 2-ethylfuran were responsible for the waxy, green flavor identified in apple wood smoked cheeses. These smoke flavor compounds, in addition to diacetyl and acetoin, were deemed important to the flavor of cheeses in this study. Results from this study identified volatile aroma-active compounds contributing to differences in sensory perception among Cheddar cheeses smoked with different wood sources.     

Determination of polycyclic aromatic hydrocarbons (PAHs) in commonly consumed Nigerian smoked/grilled fish and meat

Smoking and/or grilling, when carried out with traditional methods involving direct contact with wood combustion fumes, is responsible for high contamination levels with carcinogenic polycyclic aromatic hydrocarbons (PAHs). The aim of this work was to investigate the PAH content of different smoked or grilled meat and fish products commonly consumed in Nigeria. A rapid method involving microwave-assisted saponification and simultaneous extraction followed by solid-phase extraction (SPE), high-performance liquid chromatography (HPLC) separation and spectrofluorometric detection was employed. Samples that were smoked or grilled using traditional systems, which use a wood fire, were heavily contaminated with benzo[a]pyrene (BaP) at levels ranging from 2.4 to 31.2 µg kg^?1 wet weight. Considerably lower contamination levels were found in samples smoked or grilled in the laboratory using a charcoal fire (BaP from 0.7 to 2.8 µg kg^?1 wet weight). The health risk associated with a daily consumption of 100 g of these products was also evaluated using the margin of exposure (MOE) approach. MOE values lower than 10,000 were obtained for all smoked/grilled commercial samples, indicating a potential concern for consumer health.     

液熏斑点叉尾鲴鱼肉中熏液渗透及苯并(a)芘检测

采用修正吉布斯法和盐酸羟胺法对液熏前后熏液中酚类物质和羰基化合物含量进行比较.采用高效液相色谱法对烟熏鱼和液熏鲴鱼中苯并(a)芘含量进行检测.结果表明,鱼肉液熏处理后,羰基化合物的渗透与鱼肉烟熏色泽之间具有显著相关性(P>0.9),酚类物质的渗透,对鱼肉具有很好的抗氧化作用.液熏细鱼时,取熏液质量浓度为3%,熏制2～6h为宜.液熏鮰鱼中苯并(a)芘含量为1.00μg/kg,符合国际食品卫生要求.     

Occurrence of polycyclic aromatic hydrocarbons in smoked cheese

The presence of polycyclic aromatic hydrocarbons (PAH) in smoked cheeses of different origin was studied. The samples were subjected to an initial extraction of fat and an alkaline treatment, extracted with cyclohexane, cleaned up by means of solid-phase extraction tubes, and analyzed by gas chromatography/mass spectrometry (GC/MS) operating in selective ion-monitoring mode (SIM). The results revealed the presence of numerous polycyclic aromatic hydrocarbons in the exterior zone of the samples, some of them with methyl groups. In all cases, the concentrations of compounds of low molecular weight were much higher than those of high molecular weight. Polycyclic aromatic hydrocarbons with varying degrees of carcinogenicity were identified, including benzo(a)pyrene in concentrations, which, although they did not exceed the limit established for this compound in the rind of ripened cheeses, do exceed the limit of 0.03 microg/kg fixed for other foods smoked with smoke flavorings. Significant differences in the number and concentration of PAH in smoked cheese also were observed from rind to interior, the rind being the most contaminated zone.     

Volatile components of raw and smoked black bream (Brama raii) and rainbow trout (Oncorhynchus mykiss) studied by means of solid phase microextraction and gas chromatography/mass spectrometry

Solid phase microextraction followed by gas chromatography/mass spectrometry of raw and smoked black bream and rainbow trout was carried out. The volatile components of the raw fish belong to a limited number of groups of compounds. Raw black bream has a higher presence of acids than raw trout, while the latter contains more alcohols, hydrocarbons, esters and phenol derivatives; both contain similar concentrations of saturated aldehydes. The volatiles of the smoked fish basically comprise the compounds also detected in the raw fish together with others produced during the processing. Smoke components detected in both smoked fish species were mainly phenol, guaiacol and syringol derivatives, ketones, acetic acid and some polycyclic aromatic hydrocarbons. Smoked black bream contained a higher number and higher concentrations of smoke components than smoked rainbow trout. Large variations in concentrations of smoke components in the smoked fish samples indicated that the smoking process had not been totally homogeneous. The presence of autoxidatively derived compounds, such as unsaturated aldehydes, was mainly detected in some smoked bream samples, showing that this degradation process is not occurring homogeneously. The usefulness of the applied techniques for the study of volatile components of raw and smoked fish is shown. © 2002 Society of Chemical Industry