Exposure assessment of epoxy fatty acids through consumption of specific foods available in Belgium.

Epoxy fatty acids (EFAs) are secondary oxidation products formed from unsaturated fatty acid hydroperoxides. Seventeen food categories were analysed for C18 monoEFAs of food products available on the Belgian market. A quantitative exposure assessment was performed based on deterministic and probabilistic approaches combining these concentration data with consumption data obtained from the Belgian National Food Consumption Survey of 2004. A preliminary evaluation of any potential risk related to the intake of the studied EFAs through the studied foods was performed by applying the threshold of toxicological concern (TTC) concept. Three food categories out of 17 foods, mayonnaise, butter-margarine and ready-to-eat meals were found to contribute most to the intake of EFAs. According to probabilistic determination, these foods had P50 intakes of 0.4085, 0.3328 and 0.2997 mg kg-1 bw day-1 respectively. They had P99.5 intakes of 3.7183, 2.7921 and 38.6068 mg kg-1 bw day-1 respectively. The intake below the TTC was from the consumption of cooked meat, smoked salmon and raw cured ham, with P50 intakes of 0.0006, 0.0007 and 0.0011 mg kg-1 bw day-1 respectively, and the other foods were above the TTC. Based on the TTC concept, a risk to human health could be identified related to the consumption of cheese, snacks foods, plant oils, French fries, dry nuts, chips, cured minced raw meat, cookies, fresh and frozen salmon and bacon.

Impact of Lipid and Protein Co-oxidation on Digestibility of Dairy Proteins in Oil-in-Water (O/W) Emulsions.

Enrichment of polyunsaturated fatty acids (PUFAs) is a growing trend in the food industry. However, PUFAs are known to be susceptible to lipid oxidation. It has been shown that oxidizing lipids react with proteins present in the food and that as a result polymeric protein complexes are produced. Therefore, the aim of this work was to investigate the impact of lipid and protein co-oxidation on protein digestibility. Casein and whey protein (6 mg/mL) based emulsions with 1% oil with different levels of PUFAs were subjected to respectively autoxidation and photo-oxidation. Upon autoxidation at 70 °C, protein digestibility of whey protein based emulsions containing fish oil decreased to 47.7 ± 0.8% after 48 h, whereas in the controls without oil 67.8 ± 0.7% was observed. Upon photo-oxidation at 4 °C during 30 days, mainly casein-based emulsions containing fish oil were affected: the digestibility amounted to 43.9 ± 1.2%, whereas in the control casein solutions without oil, 72.6 ± 0.2% of the proteins were digestible. Emulsions containing oils with high PUFA levels were more prone to lipid oxidation and thus upon progressive oxidation showed a higher impact on protein digestibility.

Exposure assessment of Malondialdehyde, 4-Hydroxy-2-(E)-Nonenal and 4-Hydroxy-2-(E)-Hexenal through specific foods available in Belgium.

Malondialdehyde (MDA), 4-Hydroxy-2-(E)-Nonenal (HNE) and 4-Hydroxy-2-(E)-Hexenal (HHE) are reactive aldehydes found in foods and are formed due to decomposition of polyunsaturated fatty acid hydroperoxides. In the present study, sixteen food categories were analyzed for the aforementioned aldehydes and in combination with consumption data obtained from a national representative sample of the Belgian population, a quantitative exposure assessment was performed. MDA was detected above the detection limit in 84% of the analyzed samples while HNE and HHE in 63% and 16% of the samples respectively. Consumption of dry nuts, fried snacks, French fries and cured minced meat products were found to contribute the most to the intake of MDA and HNE. Intake of HHE from the foods analyzed was found not to be significant. An evaluation of any potential risk related to the intake of the studied aldehydes through the studied foods was performed by applying the threshold of toxicological concern concept. No risk to human health could be identified related to the consumption of these foods for the vast majority of the consumers, with the only exception of a small proportion (3.8%) of those who consume cured and minced raw meat, that could be at risk.

Spoilage potential of psychrotrophic lactic acid bacteria (LAB) species: Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium, on sweet bell pepper (SBP) simulation medium under different gas compositions.

Sweet bell peppers are a significant constituent of retail, chilled-stored and packaged food products like fresh salads, marinades and ready-to-eat (RTE) meals. Previously, through general screening of the Belgian market and by means of source tracking analysis in a plant manufacturing minimally processed, vegetable salads the susceptibility of fresh-cut sweet bell peppers to lactic acid bacterium (LAB) contamination was substantiated. The determination of the metabolic profiles of Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium, two major psychrotrophic, spoilage-related LAB species, on sweet bell pepper (SBP) simulation medium under different packaging conditions - 1.) vacuum: 100% N2, 2.) air: 21% O2, 79% N2, 3.) MAP1: 30% CO2, 70% N2 and 4.) MAP2: 50% O2, 50% CO2 - facilitated a better understanding of the spoilage potential of these microbes as well as the presumptive contribution of O2 in the spectrum of produced volatile organic compounds (VOCs) associated with poor organoleptic properties of food products. Generally, none of the applied gas compositions inhibited the growth of the 4 L. gelidum subsp. gasicomitatum isolates, however the presence of O2 resulted in buttery off-odors by inducing primarily the accumulation of diacetyl and pungent "vinegar" smell due to acetic acid. The 3 tested isolates of L. piscium varied greatly among their growth dynamics and inhibition at MAP2. They exhibited either weak spoilage profile or very offensive metabolism confirming significant intraspecies diversity.

Development and validation of a gas chromatography-flame ionization detection method for the determination of epoxy fatty acids in food matrices.

A reliable and suitable method for the determination of epoxy fatty acids in various food matrices based on the Bligh and Dyer lipid extraction procedure was developed and validated. The method involves the use of a methylated epoxy fatty acid as internal standard (IS), extraction of the analytes from the matrices followed by room temperature methylation, a three-step solid phase extraction (SPE) separation of the fatty acid methyl esters (FAMEs), and detection with gas chromatography-flame ionization detection (GC-FID). The method was validated in four different food matrices chosen as model systems, namely, vegetable oils, unprocessed pork, fried potato crisps, and infant formula. The extraction technique allows the method to be applied for routine analysis of a large amount of samples. Intraday repeatability ranged from 1 to 19%, and interday reproducibility ranged from 2 to 9%. The limit of quantification (LOQ) ranged from 3.32 to 20.47 µg g(-1) of sample with recoveries ranging from 94 to 115%. The results verify the accuracy and reproducibility of the analytical technique and its ability to provide reliable quantification of epoxy fatty acids. Finally, levels of epoxy fatty acids in several food products on the Belgian market were screened and are presented.

Improved gas chromatography-flame ionization detector analytical method for the analysis of epoxy fatty acids.

In this study an improved method for analysis of epoxy fatty acids is reported. Data obtained from analysis of polar fatty acids has previously been presented, but due to the high number of compounds that co-elute in the polar fraction, the resultant chromatograms are complex which may lead to compromising the accuracy of the data. A three steps separation of fatty acid methyl esters (FAMEs) by solid-phase extraction (SPE) on a silica gel column to remove hydroxy fatty acid interferences was proposed. This approach is opposed to a two step separation procedure that has been often used to prevent analytical interferences caused by non-altered fatty acids. A gas chromatograph with a flame ionization detector (GC-FID) equipped with a polar CP-Sil 88™ column was used. Quantification was based on the use of methyl nonadecanoate (C19:0), as an internal standard. Individual mono epoxy fatty acids were well separated without co-eluting compounds. The optimized method was finally applied to screen epoxy fatty acids in 37 fresh oil samples. Results obtained for the total epoxy fatty acids were in the range 0.03-2mgg(-1) of oil with repeatability coefficient of variation (CV) ranging from 2.8 to 9.9% for duplicate analysis showing that the results obtained are repeatable.

Malondialdehyde measurement in oxidized foods: evaluation of the spectrophotometric thiobarbituric acid reactive substances (TBARS) test in various foods.

The ability of the spectrophotometric thiobarbituric acid reactive substances (TBARS) test to determine malondialdehyde (MDA) in various food matrices was evaluated. MDA was extracted from the foods; the extract reacted with thiobarbituric acid (TBA); and the formed TBA-MDA adduct was measured spectrophotometricaly at 532 nm. In parallel, the TBA-MDA adduct was analyzed with high-performance liquid chromatography (HPLC) coupled with fluorescence detection. Oils and unprocessed and uncooked meat and fish products did not exhibit any significant difference in the amount of MDA measured by the two methods, indicating that the major substance reacting with TBA and forming an adduct that absorbs at 532 nm was MDA. However, in products such as dry nuts, pork sausages, cooked fish, and gouda cheese, an overestimation of MDA was observed, indicating that TBARS test was unsuitable for accurate determination of MDA. Furthermore, the results in the present work suggest that the overestimation of MDA by the TBARS test as it was applied is related to the interference of other than secondary lipid oxidation products.