The analysis of trans fatty acid profiles in deep frying palm oil and chicken fillets with an improved gas chromatography method

An improved gas chromatography method for the simultaneous separation of 52 fatty acids (FAs) has been developed. For both oleic acid and linoleic acid, a good resolution was achieved for their positional and geometrical (cis/trans) isomers. This method was validated to be precise, accurate and sensitive. With this method, the FAs profiles in palm oil and chicken fillets were analyzed. In general, small changes were observed in the composition of FAs and formation of trans isomers after 8 h frying at the temperature lower than 200 °C. However, with extreme deep-frying process, the thermal degradation and TFAs formation in frying oil increased in direct proportion to frying temperature and time. Moreover, the FAs composition of fried chicken fillets was found to be mostly in correspondence with that of the frying oil, which might be due to the oil absorption or interaction between the frying oils and frying materials.     

A reliable and sensitive time-resolved fluorescent immunochromatographic assay (TRFICA) for ochratoxin A in agro-products

Immunochromatographic assays (ICAs) are considered as a suitable diagnostic tool for the detection of mycotoxins. Mycotoxins and especially, ochratoxin A are analytes with more demanding sensitivity requirements. To enhance the sensitivity of current immunochromatographic assays for ochratoxin A (OTA), a novel sensitive ICA was developed in this study. In the assay, microspheres enclosing fluorescent europium (III) [Eu(III)] nanoparticles (EuNPs) were used as a label for OTA monoclonal antibody (OTA-mAb) conjugation. Accordingly, assay was called time-resolved fluorescent immunochromatographic assay (TRFICA). The test strip was composed of three parts: a sample pad, nitrocellulose membrane and an absorbent pad. As for detection, a proper concentration of conjugated microspheres was pipetted into the microtube and sample extract was added to it. Then the strip was inserted into the tube and the fluid flow along the strip. The TRFICA results were obtained in 8 min and read by a portable TRFICA strip reader. The established method allows quantitative determination of OTA with limit of detection as low as 1.0 μg kg⁻¹ in the samples. For validation, spiked samples including wheat, maize, soybean and rice were respectively assayed by TRFICA and a standard high performance liquid chromatography equipped with a fluorescence detector (HPLC-FLD), and good agreement of results was obtained between two methods.     

Current major degradation methods for aflatoxins: A review

BackgroundAflatoxins are strong cancerogenic compounds predominantly produced by certain strains of the Aspergillus genus. Due to their extreme stability in different conditions, it is very difficult to remove them completely in human diet and animal feeds. In this way aflatoxins are triggering numerous healthy problems (such as liver cancer) and thus becoming a huge burden to the hygiene system and food industry worldwide.Scope and approachTherefore, seeking for an effective technique to degrade aflatoxins to a threshold level has been a “hot-topic” among researchers. Traditional methods to detoxify aflatoxins include physical and chemical treatments, such as an extrusion cooking process and ammoniation, respectively. Meanwhile a bio-degradation by microorganisms gains its popularity due to its friendliness to both environment and body health. Natural phytochemicals (plant extracts) which have great capability to remove aflatoxins without causing any damage on human and animals come out as an improvement.Key findings and conclusionHowever, a fully and systematically discussion of the methods of detoxification for aflatoxins is still not available. Therefore, in the present review we briefly enumerate several traditional strategies, update newly methods, particularly the potential use of natural phytochemicals, and discuss some mechanisms during the detoxification period, summarizing merits and demerits of these methods. We suggest that this important information and our humble opinions could help researchers to understand the degradation of methods for aflatoxins.     

Discriminant analysis of Mediterranean pine nuts (Pinus pinea L.) from Chilean plantations by near infrared spectroscopy (NIRS)

Pinus pinea L. is one of the most important nut species in the world given the high nutritional and culinary value of its seed, the pine nuts, with increasing demand. The objective of this study was to assess the potential of visible and near infrared spectroscopy (VIS + NIRS) to analyse different sample presentations and to discriminate geographical origins of Mediterranean pine nut grown in Chile. Pine nuts were collected from 76 adult trees in three growth macrozones previously defined for stone pine in Chile. Original spectroscopic data were obtained by means of a Foss NIRSystems 6500 SYII spectrophotometer using a transport module. Reflectance was employed in the wavelength range of 400–2500 nm. The best means of sampling for the pine nuts used in this study were also studied. After analysing the spectroscopic data, discriminant models were obtained by means of discriminant partial least square (DPLS) with all samples. For the three macrozones previously identified, 87.8% of samples was correctly classified in the cross validation stage with the best model for pine nuts spectra analysis, obtained with shelled intact pine nuts. Results indicate that NIRS technology is capable of differentiating between pine nut samples of different geographical origins with errors ranging between 12.2 and 9.2%, and demonstrate the potential of VIS + NIRS technology as a rapid and accurate method for predicting the geographical origin of Mediterranean pine nuts.     

A survey of the incidence and level of aflatoxin contamination in a range of locally and imported processed foods on Malawian retail market

Samples of locally (Malawian) processed and imported maize- and groundnut-based food products (peanut butters, roasted groundnuts, peanut based therapeutic foods, instant baby cereals, maize puffs and de-hulled maize flour) were collected from popular markets of Lilongwe City, Malawi. The samples were analysed in order to determine the frequency and extent of aflatoxin contamination, using immuno-affinity column and reversed-phase liquid chromatography with post-column photochemical derivatization and fluorescence detection. No aflatoxins were detected in all samples of imported baby cereal and locally processed de-hulled maize flour. However, all locally processed maize based baby foods had aflatoxins above EU maximum tolerable level of 0.1 μg/kg. In 75% of locally processed maize puffs, aflatoxins were detected at levels of up to 2 μg/kg. Peanut based therapeutic foods had aflatoxin level between 1.6 and 2.9 μg/kg, exceeding the EU tolerable maximum level (0.1 μg/kg) set for food for health purposes. Locally processed peanut butters had aflatoxins levels in the range of 34.2–115.6 μg/kg, which was significantly higher than their imported counterparts (<0.2–4.3 μg/kg). Samples of locally processed skinned and de-skinned roasted groundnuts had aflatoxins in range of 0.5–2.5 μg/kg and 0.6–36.9 μg/kg, respectively. These results highlight the need for rigorous monitoring of aflatoxins in commercially available processed products in order to reduce likely health risks associated with dietary aflatoxin intake.     

Diminution of aflatoxin B1 production caused by an active packaging containing cinnamon essential oil

The antifungal and antimycotoxigenic action of an active package containing cinnamon essential oil have been evaluated against the mold Aspergillus flavus on the aflatoxin B1 production. Two independent experiments were carried out, the first one with cinnamon on a paper diffusion disc placed in vapor phase and the second one with an active PP (Polypropylene) films containing the essential oil. The culture media, exposure time, closure of the Petri dish and cinnamon concentration were evaluated. The first experiment revealed an important reduction on mycotoxin, even when the mold grew, and the action remained for 15 days. The second experiment highlighted the importance of cinnamon concentration on the antimycotoxigenic action, achieving a strong reduction with the sub-inhibitory concentration (2% of cinnamon) and a complete reduction with fungicidal concentration (4% and 6% cinnamon). The UPLC system coupled to a fluorescence detector was optimized for analysis of aflatoxin B1.     

化学计量学与三酰甘油酯在食用油保真中的研究进展

食用植物油保真检测技术是食用植物油打假和保证人民身体健康的重要手段。三酰甘油酯是占食用植物油90%以上的主要成分,但是我国目前的检测技术仅能检测三酰甘油酯酰基链结构,即通过甲酯化方式检测脂肪酸含量,该方法不能真实反映三酰甘油酯的结构和含量。本文综述国内外最新的三酰甘油酯分析技术和化学计量学分析三酰甘油酯指纹谱的食用植物油保真检测技术研究进展,为保障我国食用植物油安全消费提供重要的技术支撑。     

HPLC determination of ochratoxin A in high consumption Tunisian foods

Samples (180) of high consumption food commodities from various regions of Tunisia were analysed to determine ochratoxin A contamination levels. A high performance liquid chromatography method for ochratoxin A determination was optimized. Samples were extracted with acetonitrile/water (80:20, v/v) solution and purified by immunoaffinity column. Average recoveries at 0.5 and 2 ng/g levels ranged from 84 ± 3.1 to 94 ± 1.2% with a between-day coefficient of variation (RSDR) of 3.8%. The method detection limit was 0.1 ng/g and ochratoxin identity was confirmed by methyl ester formation. The whole procedure was simple and fast if compared with other existing procedures. Performed analysis indicates that 45% of monitored samples were contaminated with levels ranging from 0.11 to 33.9 ng/g. The most contaminated commodities were barley, sorghum and wheat.     

Multimycotoxin analysis of sorghum (Sorghum bicolor L. Moench) and finger millet (Eleusine coracana L. Garten) from Ethiopia

The natural contamination of sorghum and finger millet by toxigenic fungi and associated mycotoxins has been studied. All the tested sorghum and finger millet samples were found to be contaminated by Fusarium and Aspergillus species. Sorghum was considerably more likely to be contaminated by both genera than finger millet. Penicillium, Alternaria, Rhizopus and Epicoccum species were also present in both grains albeit at lower frequencies. Multimycotoxin analysis using LC–MS/MS revealed the contamination of sorghum and finger millet by 84 and 62 metabolites, respectively. The prevalence of major mycotoxins was lower than 15% in sorghum except zearalenone that occurred in one third of the samples at average level of 44 μg/kg. In finger millet major mycotoxins occurred at a prevalence of 6–52% with zearalenone being the dominant and occurring at average level of 76 μg/kg. Aflatoxins B₁, B₂, G₁, G₂ and M₁ were detected in at least one sorghum sample while only aflatoxins B₁ and G₁ were present in finger millet samples. The average aflatoxins B₁ and G₁ concentrations in sorghum have been higher than European standards. But the level of B₂, G₂ and M₁ in sorghum and that of B₁ and G₁ in finger millet have been lower. Apart from aflatoxin precursors and other Fusarium metabolites, a broad range of additional metabolites were detected in sorghum and finger millet.     

Development of a colloidal gold strip for rapid detection of ochratoxin A with mimotope peptide

Ochratoxin A (OTA), a mycotoxin mainly produced by some Aspergillus and Penicillium species, is found in cereals, coffee, wine, pork and grapes. The kidney and liver are the target organs of OTA, resulting in teratogenicity, carcinogenicity, and mutagenicity. To avoid the risk of OTA consumption, raw materials should be identified and removed from distribution. Current procedures for detection of OTA are time-consuming and involve sophisticated equipment. Furthermore, materials containing OTA is a biohazard for manufacturers and consumers. In this study, a rapid, inexpensive, and user-friendly lateral flow strip assay ideally suited for on site testing of OTA was developed. Moreover, mimotope peptide capable of mimicking OTA by panning from a M13 phage-displayed random seven-peptide was used instead of OTA–protein conjugate. Ten ppb of OTA was detected in 10 min by this new strip. The results indicated that a rapid method without using the mycotoxin, but using mimotope peptides was developed to screen OTA; related methods also can be developed to screen other mycotoxins.