Solid phase extraction (SPE) method for detection of irradiated meats

Solid phase extraction (SPE) has been proposed as an alternative to the currently used florisil column chromatography. The hydrocarbons formed from beef, pork and chicken irradiated with 0-10 kGy were determined by the SPE and quantified by GC/MS. The limit of detection for the hydrocarbons in irradiated meats was 0.5 kGy. The correlation between the irradiation dose and the concentrations of hydrocarbons in beef, pork and chicken was high that linear regression coefficients (r²) were 0.87-0.99. SPE method would be used as the rapid detection of irradiated meats.     

Analysis of radiolytic products of lipid in irradiated dried squids (Todarodes pacificus)

The lipid portion of dried squids (Todarodes pacificus) was extracted, and its hydrocarbons and 2-alkylcyclobutanones were separated using a florisil column. Both compounds were identified by gas chromatography and mass spectrometry and used to investigate the production of radiation-induced hydrocarbons and 2-alkylcyclobutanones. Concentrations of the hydrocarbons and 2-alkylcyclobutanones increased linearly with the radiation dosage. The major hydrocarbons in the irradiated dried squids were pentadecane and 1-tetradecene, which originated from palmitic acid. The amount of pentadecane was the highest among the radiation-induced hydrocarbons in the dried squids. The major 2-alkylcyclobutanone in the irradiated dried squids was 2-dodecylcyclobutanone, which was formed from the large amount of palmitic acid. 2-Tetradecylcyclobutanone, which may be produced from stearic acid in sample lipids, was also detected. Radiation-induced hydrocarbons and 2-alkylcyclobutanones were detected at > or = 0.5 kGy. These compounds were not detected in dried squids that were not irradiated. Radiation-induced hydrocarbons can be used as a detection marker for irradiated dried squids; however, the amount of 2-alkylcyclobutanones produced was not enough to be used as a marker. Radiolytic products of lipids, such as hydrocarbons or 2-alkylcyclobutanones. can be used to monitor food safety for consumers, ensuring proper irradiation labeling in foods and quarantine treatment in international trade.     

Analysis of radiation-induced hydrocarbons and 2-alkylcyclobutanones from dried shrimps (Penaeus aztecus)

We investigated the usefulness of hydrocarbons and 2-alkylcyclobutanones as markers for irradiated, dried shrimps. A method was developed to detect the irradiation of dried shrimps (Penaeus aztecus) by identifying radiation-induced hydrocarbons and 2-alkylcyclobutanones extracted from dried shrimps, which were separated by Florisil column chromatography and identified by a method using gas chromatography/mass spectrometry. Radiation-induced hydrocarbons and 2-alkylcyclobutanones are formed from the fatty acids of the irradiated fats. The quantity of the hydrocarbons and 2-alkylcyclobutanones formed from some fatty acids is related to the composition of fatty acids in a sample. The concentrations of hydrocarbons and 2-alkylcyclobutanones increased with radiation dose. The major hydrocarbons in the irradiated, dried shrimps were 1-tetradecene and pentadecane from palmitic acid; small amounts of heptadecane and 1-hexadecene from stearic acid; and 8-heptadecene and 1,7-hexadecadiene from oleic acid. 2-(5'-Tetradecenyl)cyclobutanone, one of the 2-alkylcyclobutanones, was present at the highest concentration. The radiation-induced hydrocarbons and 2-alkylcyclobutanones were detected at radiation doses of 0.5 kGy and greater. These compounds were not detected in nonirradiated, dried shrimps.     

Hydrocarbons detected in irradiated pork,bacon and ham

Hydrocarbons produced by γ-radiation of pork, bacon and ham were analyzed to determine how irradiation affects the production of the hydrocarbons and whether the hydrocarbons can be used for identifying post-irradiation of pork, bacon and ham. Hydrocarbons were determined by a sequential procedure of lipid extraction by hexane, Florisil column chromatography and gas chromatography. Hydrocarbons C17:1, C16:2, C17:2 and C16:3 were detected in pork, bacon and ham irradiated at 0.5 kGy or higher, but not in non-irradiated ones except C17:1. The detection levels in all the irradiated samples were in the order of C16:2, C17:1, C17:2 and C16:3 from the highest to the lowest.     

Detection of irradiated food: A review

The sale of irradiated food in the UK has been legal since the start of 1991 with the proviso that it must be labelled as such. At present there are no methods sufficiently accurate and reliable for the routine detection of irradiated food of all varieties. The current state of development of different physical, chemical and biological methods available is reviewed. These comprise electron paramagnetic resonance, luminescence, viscosity changes, detection of radiation-induced chemical species such as volatile hydrocarbons and o-tyrosine by chromatographic-mass spectrometric techniques, changes to DNA and changes in microflora.     

Application of electron paramagnetic resonance (EPR) spectroscopy for control of irradiated food

Four groups of foodstuffs were irradiated in a ⁶⁰Co source with doses from 0.3 to 10kGy and subsequently measured by EPR spectrometry at room temperature in air: (1) poultry bones and fins, scales and bones of carp. (2) seeds of selected fruits, (3) dehydrated mushrooms, and (4) a selected set of spices and herbs. Qualitative and, in some cases, quantitative data related to the absorbed dose of radiation were collected. In the irradiated bones from poultry and carp an asymmetric singlet (g_I = 2.0030, g_II =1.9973; ΔH_pp = 0.85 mT) was detected which was stable at room temperature and was similar to that previously found in irradiated mammalian bones. Another stable EPR signal (g₀ = 2.0024, ΔH_pp = 0.56 mT) was found in the fins and scales of carp which was about five times more intense in fins than in scales. In pips of pears irradiated with a dose of 3 kGy. a signal which was about twice as intense as the endogenous signal was recorded. A multicomponent EPR signal derived from the stones of dates differed from the endogenous signal even when a low dose (0-5 kGy) was applied. A multicomponent EPR signal is also observed in dried mushrooms irradiated with a dose of 3 kGy. In white mustard, paprika and chilli no native EPR signal exists and a radiation-induced stable EPR signal can still be observed after a period of 3 months. The radiation-induced EPR signal in black pepper was highly sensitive to moisture and disappeared, yet the native signal survived. The pilot experiments performed with irradiated stones of cherries, plums, lemons, apple pips, raspberries, cranberries, red currants, blackcurrants, gooseberries and tomatoes showed the induction of short-lived EPR signals of no practical use for the control of food irradiation.     

Hydrocarbons detected in irradiated and heat-treated eggs

Shell eggs were non-irradiated or irradiated at 0.5, 1 and 3 kGy, and boiled, fried or heated in ovens. Hydrocarbons were determined by a sequential procedure of lipid extraction by hexane, Florisil column chromatography and gas chromatography. Hydrocarbons 15:0, 14:1, 17:0, 16:1, 17:1, 16:2, 17:2 and 16:3 were detected in shell eggs irradiated at 0.5 kGy or higher, but not in non-irradiated ones except 15:0 and 17:0. Boiling non-irradiated or irradiated eggs for 40 min little affected detection levels of the hydrocarbons. Frying the egg yolk of the non-irradiated eggs for 5 min produced hydrocarbons 17:1 and 17:2 besides 15:0 and 17:0. Hydrocarbons 15:0, 17:0, 17:1, 17:2, 14:1 and 16:1 were detected in the egg yolk of the non-irradiated eggs while heating it in a cooking oven at 170°C for 60 min. The pattern of hydrocarbons detected in non-irradiated samples when heated was, however, notably different from that of irradiated ones; detection of hydrocarbons in shell eggs or egg products could, thus, identify their post-irradiation.     

Improved clean-up for the determination of lasalocid in 'difficult' food matrices

Methodology has been developed for the determination of lasalocid in analytically 'difficult' matrices such as processed and spiced foods. The procedure was based on an existing silica-based solid-phase extraction (SPE) clean-up to which was added a novel NH 2 SPE step before HPLC with fluorescence detection. Use of the additional step enabled the determination of lasalocid in matrices such as baby food, meat pies ('pasties'), etc. Analysis of these matrices was not possible using the standard clean-up on its own. Chromatography showed a massive reduction in the amount of co-extractives and interferences. Validation data were obtained down to the 10-40 μg kg -1 level for a range of products. Recoveries ranged from 74% at 10 μg kg -1 for pork sausages to 96% at 40 μg kg -1 for meat pies.     

A quick method for identifying radiolytic hydrocarbons in low‐fat‐containing food

BACKGROUND: As radiation‐induced alterations of the lipid fraction of foods are related to their initial fat content, concentrations of fat degradation products used as irradiation markers are expected to be lower when irradiating low‐fat‐containing foods. Thus the sensitivity required when applying analytical methods for identifying irradiation markers in foods eventually depends on their respective amounts of fat. The aim of this study was to perform the qualitative analysis of characteristic hydrocarbons resulting from irradiation of samples with a fat content as low as 25 g kg^?1. RESULTS: A rapid extraction using a small amount of ethyl acetate was the unique sample pretreatment required to accomplish the analysis of radiolytic markers by using on‐line coupling of reverse phase liquid chromatography and gas chromatography with mass spectrometry detection (RPLC/GC/MS). Efficient elimination of the large volumes (up to 2170 µL) directly transferred from LC to GC was achieved by optimising the operation mode of the through‐oven transfer adsorption/desorption system used as interface. CONCLUSION: The reported procedure allowed confirmation, in less than 65 min, of the occurrence of up to five irradiation markers, namely n‐pentadecane, 1‐hexadecene, 1,7‐hexadecadiene, n‐heptadecane and 8‐heptadecene, in cooked ham irradiated at doses as low as 2 kGy. © 2012 Society of Chemical Industry     

Comparison of efficiency of different sorbents used during clean-up of extracts for determination of polychlorinated biphenyls and pesticide residues in low-fat food

A model mixture (containing α-linolenic acid as interfering substance) for polychlorinated biphenyls (PCBs) and organochlorine pesticides determination was subjected to clean-up with various solid-phase extraction (SPE) columns. Octadecylsilyl (C-18), graphitised non-porous carbon (Envi-Carb), aminopropyl (NH₂), Florisil and Alumina SPE sorbents were evaluated. The relative sample clean-up provided by these SPE columns was evaluated using gas chromatography with electron capture detection (GC–ECD). The Florisil, Alumina and NH₂ columns were found to provide the most effective clean-up, removing the greatest amount of interfering substance, and simultaneously ensuring analyte recoveries higher than 70% for most compounds. The Envi-Carb and C-18 columns did little to eliminate matrix interferences. The developed clean-up procedure has been applied to real low-fat food samples, such as herring (Clupea harengus). Recoveries >78% with standard deviations (SD) <15% were obtained for all compounds under the selected conditions. Method quantification limits (MQLs) were in the 5–10 μg/kg range.     

Detection of radiation-induced hydrocarbons and 2-alkylcyclobutanones in irradiated perilla seeds

The method consists of the extraction of fat from perilla seeds, separation of hydrocarbons and 2-alkylcyclobutanones with florisil column chromatography, and identification of hydrocarbons and 2-alkylcyclobutanones by gas chromatography-mass spectroscopy (GC-MS). Concentrations of hydrocarbons and 2-alkylcyclobutanones increased with the irradiation dose. The major hydrocarbons in the irradiated perilla seeds were 8-heptadecene and 1,7-hexadecadiene from oleic acid and 6,9-heptadecadiene and 1,7,10-hexadecatriene from linoleic acid. One of the 2-alkylcyclobutanones, 2-(5'-tetradecenyl)cyclobutanone, was found in the highest concentration in the irradiated perilla seeds. Radiation-induced hydrocarbons in the perilla seeds were detected at doses of 0.5 kGy and higher, and radiation-induced 2-alkylcyclobutanones were detected at doses of 1 kGy and higher. These compounds were not detected in nonirradiated perilla seeds.     

Mass spectrometry‐based lipidomics in food science and nutritional health: A comprehensive review

With the advance in science and technology as well as the improvement of living standards, the function of food is no longer just to meet the needs of survival. Food science and its associated nutritional health issues have been increasingly debated. Lipids, as complex metabolites, play a key role both in food and human health. Taking advantages of mass spectrometry (MS) by combining its high sensitivity and accuracy with extensive selective determination of all lipid classes, MS‐based lipidomics has been employed to resolve the conundrum of addressing both qualitative and quantitative aspects of high‐abundance and low‐abundance lipids in complex food matrices. In this review, we systematically summarize current applications of MS‐based lipidomics in food field. First, common MS‐based lipidomics procedures are described. Second, the applications of MS‐based lipidomics in food science, including lipid composition characterization, adulteration, traceability, and other issues, are discussed. Third, the application of MS‐based lipidomics for nutritional health covering the influence of food on health and disease is introduced. Finally, future research trends and challenges are proposed. MS‐based lipidomics plays an important role in the field of food science, promoting continuous development of food science and integration of food knowledge with other disciplines. New methods of MS‐based lipidomics have been developed to improve accuracy and sensitivity of lipid analysis in food samples. These developments offer the possibility to fully characterize lipids in food samples, identify novel functional lipids, and better understand the role of food in promoting healt.     

Effects of processing and storage on the stability of free and esterified carotenoids of red peppers (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) and hot chilli peppers (<Emphasis Type="Italic">Capsicum frutescens</Emphasis> L.)

The stability of non-esterified carotenoids and carotenoid esters in paprika and chilli powder as affected by various processing treatments and storage conditions were studied. For this purpose, freshly harvested chilli and paprika pods were minced, immediately heated at 80, 90 and 100 °C for 5 and 10 min, respectively, and lyophilised. Alternatively, thermal treatment prior to mincing was applied. Processing resulted in a 25–34% loss of the initial carotenoid contents in chilli and 20–53% in paprika. Degradation of individual non-esterified carotenoids, mono- and diesters was monitored, generally showing an increased processing stability of mono- and diesters compared to their non-esterified counterparts. Capsanthin, capsorubin, zeaxanthin and β-cryptoxanthin mono- and diesters esterified with saturated fatty acids displayed similar stabilities, whereas susceptibility of the non-esterified pigments to degradation differed considerably. During storage over 4 months at ambient temperature pigment contents dropped by 16.7 and 9.6% in chilli and by 39.7 and 38.8% in paprika powders with and without illumination, respectively.     

Co-occurrence of aflatoxins,ochratoxin A and zearalenone in Capsicum powder samples available on the Spanish market

The aim of this study was to determine the co-occurrence of aflatoxins (AFs), ochratoxin A (OTA) and zearalenone (ZEA) in paprika and chilli samples purchased in Spain, using HPLC with fluorescence detection. The occurrence of mycotoxin in 64 paprika samples was 59% for AFs, 98% for OTA and 39% for ZEA, whereas in the 35 chilli samples, the contamination was 40% for AFs, 100% for OTA and 46% for ZEA. None of the samples had AFs levels higher than the legally allowable limits. Regarding the co-occurrence of mycotoxins, 75% of paprika samples and 65% of chilli samples contained more than one mycotoxin. Chilli samples generally had lower concentrations of AFB1, AFB2, total AFs and OTA than had paprika samples. The high incidence of OTA contamination suggests that additional legislation may be required to for these kinds of spices.     

Dose-dependent changes of chemical attributes in irradiated sausages

To determine the effects of irradiation on the chemical attributes of sausages, TBARS values, volatile compounds, gaseous compounds, and hydrocarbons of vacuum-packaged sausages were analyzed during 60 d of refrigerated storage. A sulfur-containing volatile (dimethyl disulfide), a gas (methane), and radiation-induced hydrocarbons (1-tetradecene, pentadecane, heptadecane, 8-heptadecene, eicosane, 1, 7-hexadecadiene, hexadecane) were mainly detected in irradiated sausages and the concentrations of these compounds were irradiation dose-dependent with R(2) = 0.9585, 0.9431, and 0.9091-0.9977, respectively. Especially methane and a few hydrocarbons were detected only in irradiated sausages and their amounts were dose-dependent. On the other hand, TBARS values, other off-odor volatiles (carbon disulfide, hexanal), and gases (carbon monoxide, carbon dioxide) were found both in irradiated and nonirradiated sausages. Therefore, it is suggested that radiation-induced hydrocarbons (1-tetradecene, pentadecane, heptadecane, 8-heptadecene, eicosane, 1, 7-hexadecadiene, hexadecane), dimethyl disulfide, and methane can be used as markers for irradiated sausages.     

热释光法在辐照食品检测中出现假阳性问题的探讨

目的探讨热释光法在辐照食品检测中出现假阳性的问题。方法按照标准EN1788-2001《食品与硅酸盐矿物隔绝的食品的辐射检验热致发光法》,采用热释光法对深海鱼加工产品进行辐照食品检测。结果与花椒粉等典型辐照样品不同,深海鱼加工产品虽然检测结果为阳性,但其谱图与典型辐照样品谱图存在一定差异。主要表现为一次发光曲线中,典型辐照样品谱图的发光峰下降舒缓,峰型符合正态分布;而深海鱼加工产品的发光峰下降陡峭,并不符合正态分布。据此,怀疑热释光法对深海鱼加工产品的检测分析结果实为假阳性。结论建议在对深海鱼产品进行辐照检测时,谨慎选用热释光法或采用其他检测方法如气相色谱分析碳氢化合物法进行复验。     

Determination of 1-phenylazo-2-naphthol (Sudan I) in chilli powder and in chilli-containing food products by GPC clean-up and HPLC with LC/MS confirmation

A simple and rapid method is reported for the routine determination 1-phenylazo-2-naphthol (Sudan I) in chilli powder and in chilli-containing food products. The method involved Soxtec extraction from the products followed by high-pressure gel permeation chromatographic clean-up collecting the appropriate fraction. Analysis of this fraction was by HPLC with UV/VIS detection. The limit of detection was 7 μg kg^-1 and the limit of quantification was 13 μg kg^-1. The identity of Sudan I in food products was established by electrospray LC/MS with MS/MS confirmation. From a small survey of 30 retail samples, 11 samples of crushed chilli, Italian pasta, chilli-snack and vegetable sauce contained levels of Sudan I ranging from 24 to 5591 μg kg^-1.     

The determination of aflatoxins in spices by immunoaffinity column extraction using HPLC

Seventy‐five samples of different spices marketed in Turkey were purchased from bazaars, herbal shops and supermarkets. Equal amounts of paprika, chilli, black peppers and cumin were purchased and used to test and compare the amount of aflatoxin contamination. Two different analytical methods were examined for their efficacy by adding a known amount of aflatoxin to the blank samples of paprika. Twenty‐seven paprika, all the chilli powder and four ground black pepper samples were contaminated with aflatoxin B₁ in the range of 0.5–116.4, 1.6–80.4 and 0.3–1.2 μg kg^?1 respectively. Twenty‐three (30%) paprika and chilli powder samples were above the regulatory limits used in the European Union. No aflatoxin contamination was detected in the cumin samples at a detection limit of 0.2 μg kg^?1.     

An overview of solid‐phase extraction of food flavor compounds and chemical residues

Abstract

Solid‐phase extraction (SPE) is a rapid and sensitive sample preparation technique whose use has increased considerably within the last decade. This emerging technology has successfully replaced many tedious conventional methods of isolation and extraction of various chemicals in food, environmental, pharmaceutical, and biological samples. Sample preparation and concentration via SPE can be achieved in a one‐step extraction, and the methodology is appropriate for isolating trace amounts of chemical compounds from complex matrices. This paper gives an overview on the use of SPE as a sample preparation tool for the isolation of flavor compounds and chemical residues in food. Applying SPE in the areas of food science and agriculture will be valuable in assuring the safety and quality of our food products.     

Detection of irradiated food using 2-alkylcyclobutanones as markers: verification of the european committee standardization method EN1785 for the detection of irradiated food containing lipids

2-Alkylcyclobutanones (ACBs) are specific radiolytic products in irradiated lipid-containing food and can be used to detect irradiation of foodstuffs. EN1785, a European Committee Standardization Method, can detect 2-dodecylcyclobutanone (DCB) and 2-tetradecylcyclobutanone (TCB), which are ACBs, using GC/MS, thereby allowing judgement as to whether foodstuffs have been irradiated. In this study, the performance of EN1785 as a qualitative test in a single laboratory was evaluated and its applicability to beef, pork, chicken and salmon was verified. In the performance evaluation test, lipids extracted from unirradiated food using the Soxhlet extraction method were used as negative samples. Further, negative samples, to which DCB and TCB were added at 0.05 μg/g lipid (equivalent to the amount generated in food when irradiated at 0.5 kGy or more), were used as positive samples. For each food type examined, 4 negative and 16 positive samples were analyzed by EN1785 to verify the method's ability to detect irradiation. All of the negative samples were judged negative and all of the positive samples were judged positive. Thus, the method should be able to detect irradiation in beef, pork chicken and salmon irradiated at 0.5 kGy or higher. Next, to confirm that this is the case, the same types of food examined above, both unirradiated and irradiated at doses of 0.5-4 kGy, were analyzed by the method. All of the unirradiated samples were judged negative and all of the irradiated samples were judged positive. In a laboratory different from the one where the aforementioned evaluation was conducted, a performance evaluation test was carried out. Blind coded samples, including unirradiated and irradiated samples, were then analyzed in the laboratory according to EN178S. Ten samples (2 unirradiated and 8 irradiated samples) were analyzed for each type of food and the verified method was found to be 100% accurate. Even after the irradiated foodstuffs had been frozen for 6-9 months, it was still possible to judge whether the foodstuffs had been irradiated or not using the EN1785 method.