Institut für Lebensmittelchemie

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/8

Browse

Now showing 1 - 7 of 7

Analysis of acrylamide in vegetable chips after derivatization with 2-mercaptobenzoic acid by liquid chromatography–mass spectrometry
(2022) Oellig, Claudia; Gottstein, Eva; Granvogl, Michael
Since many years, acrylamide (AA) is a well-known toxicologically relevant processing contaminant (“food-borne toxicant”). However, only during the recent years, high levels of acrylamide have been reported in vegetable chips. In the present study, AA was quantitated via a modified derivatization procedure with 2-mercaptobenzoic acid based on stable isotope dilution analysis and liquid chromatography–mass spectrometry. Extraction with a modified QuEChERS (quick, easy, cheap, efficient, rugged, safe) method, defatting with n -hexane, and a solid phase extraction clean-up with strong cation-exchange material were performed prior to the derivatization step. Limits of detection and quantitation (LoD and LoQ) were 12 and 41 µg of AA/kg of vegetable chips (estimated via signal-to-noise ratios of 3:1 and 10:1, respectively), and thus below the LoQ of 50 µg/kg requested by the European Food Safety Authority. Recovery rates between 92 and 101% at four spiking levels with a good precision expressed as a relative standard deviation < 7% were determined. With this method at hand, a survey of the current AA amounts in 38 vegetable chips from the worldwide market was performed, showing a remarkable variability between the different vegetables, but also between different products of the same vegetable. Thereby, the AA amounts ranged between 77.3 and 3090 µg/kg, with an average of 954 µg/kg which was distinctly higher in comparison to commercially available potato chips also analyzed in the present study (12 samples, range: 117–832 µg/kg, average: 449 µg/kg). While for sweet potato and parsnip relatively low AA amounts were found, beetroot and carrot showed rather high contents.
Analysis of mono-, di-, triacylglycerols, and fatty acids in food emulsifiers by high-performance liquid chromatography–mass spectrometry
(2021) Schick, Dinah; Link, Katharina; Schwack, Wolfgang; Granvogl, Michael; Oellig, Claudia
Mono- and diacylglycerols (MG/DG) of fatty acids (FA), known as emulsifiers of the type E 471, are food additives used to adjust techno-functional properties of various foodstuffs. These emulsifiers, however, are not defined single compounds but comprise, in addition to MG and DG, other constituents such as FA, triacylglycerols (TG), and glycerol. Although the emulsifiers’ compositions affect techno-functional properties of the food, knowledge of the composition is scarcely available, and the emulsifiers and their dosage are generally chosen empirically. Thus, a simple and rather inexpensive method for the simultaneous determination of FA, 1-MG, 2-MG, 1,2-DG, 1,3-DG, and TG by high-performance liquid chromatography–mass spectrometry including a straightforward quantitation strategy has been developed. Reversed-phase chromatography with gradient elution offered adequate separation of 29 considered analytes within 21 peaks, while mass-selective detection provided their unequivocal identification. The quantitation strategy based on calibration just with the C16:0 representatives of each lipid class and a corresponding response factor system has proven to provide reliable results. The determined concentrations of different mixtures comprising varying compositions and concentrations of C16:0, C18:0, and C18:1 components of each lipid class deviated < 20% (n = 351) from the respective target concentrations. Limits of decision were determined to 0.3–0.8 mg/L and limits of quantitation to 0.8–1.7 mg/L, expressed as C16:0 representatives. Application of the method to various E 471 emulsifiers provided detailed data on their chemical compositions, and calculated FA compositions matched very well those determined by common methods such as gas chromatography with flame ionization detection.
Chlorinated paraffin screening in chocolate products and infant formula by planar solid phase extraction
(2026) Geyer, Sandra; Kaffenberger, Patrick; Steliopoulos, Panagiotis; Oellig, Claudia; Geyer, Sandra; Institute of Food Chemistry, Department of Food Chemistry and Analytical Chemistry, University of Hohenheim, Garbenstraße 28, 70599, Stuttgart, Germany; Kaffenberger, Patrick; Institute of Food Chemistry, Department of Food Chemistry and Analytical Chemistry, University of Hohenheim, Garbenstraße 28, 70599, Stuttgart, Germany; Steliopoulos, Panagiotis; Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weißenburger Straße 3, 76187, Karlsruhe, Germany; Oellig, Claudia; Institute of Food Chemistry, Department of Food Chemistry and Analytical Chemistry, University of Hohenheim, Garbenstraße 28, 70599, Stuttgart, Germany
A planar solid phase extraction with visual light detection (pSPE–Vis) was developed to screen chlorinated paraffins (CP) in chocolate products and infant formula. The analysis of selected persistent organic pollutants, such as polychlorinated biphenyls, excluded co-elution with CP. Separation and detection of CP in the target zone were obtained after simple-to-perform sample preparation, including a sulfuric acid treatment. The validation study for CP showed recoveries near 100%, a limit of decision of 7.8 ng g −1 , and a limit of detection of 15.7 ng g −1 sample. The analysis of 63 samples from the German market revealed CP up to 260 ng g −1 in chocolate products and 54 ng g −1 in infant formula, which underlines the need for CP monitoring in food. The results are comparable with literature data and were evaluated in an interlaboratory test. The pSPE–Vis method is a cost-effective tool for total CP screening. Developed for initial screening, the method enables the detection of CP-contaminated samples, supporting their prioritization for more detailed follow-up analysis by HRMS.
Identification and quantification of dicarboxylic fatty acids in head tissue of farmed Nile tilapia (Oreochromis niloticus)
(2021) Lehnert, Katja; Rashid, Mamun M.; Barman, Benoy Kumar; Vetter, Walter
Nile tilapia (Oreochromis niloticus) was grown in Bangladesh with four different feeding treatments as part of a project that aims to produce fish in a cost-effective way for low-income consumers in developing countries. Fillet and head tissue was analysed because both tissues were destined for human consumption. Gas chromatography with mass spectrometry (GC/MS) analyses of transesterified fatty acid methyl ester extracts indicated the presence of ~ 50 fatty acids. Major fatty acids in fillet and head tissue were palmitic acid and oleic acid. Both linoleic acid and polyunsaturated fatty acids with three or more double bonds were presented in quantities > 10% of total fatty acids in fillet, but lower in head tissue. Erucic acid levels were below the newly proposed tolerable daily intake in the European Union, based on the consumption of 200 g fillet per day. Moreover, further analysis produced evidence for the presence of the dicarboxylic fatty acid azelaic acid (nonanedioic acid, Di9:0) in head tissue. To verify this uncommon finding, countercurrent chromatography was used to isolate Di9:0 and other dicarboxylic acids from a technical standard followed by its quantification. Di9:0 contributed to 0.4–1.3% of the fatty acid profile in head tissue, but was not detected in fillet. Fish fed with increasing quantities of flaxseed indicated that linoleic acid was the likely precursor of Di9:0 in the head tissue samples.
Quantification of tocochromanols in vitamin E dietary supplements by instrumental thin-layer chromatography
(2022) Kröpfl, Alexander; Schweizer, Sina; Vetter, Walter
A variety of vitamin E dietary supplement capsules (DSC) based on different natural oils or synthesis products are currently found on the market whose vitamin contents need to be controlled before and after marketing. Here, we present an instrumental thin-layer chromatography (TLC) method which allows a direct determination of all tocopherols (T) and tocotrienols (T3) as well as α-tocopherol acetate simultaneously in one run with short analysis time. For this purpose, contents of the DSC were extracted, applied on silica gel 60 plates, and developed with n-hexane/ethyl acetate/acetic acid, 90:10:2 (v/v/v) as mobile phase. The UV scan of the plate at 293 nm was used for quantification based on the peak height. Following the scan, the plate was treated with 10% sulphuric acid in methanol which led to characteristic yellow-to-brown colouring of the tocochromanol spots which allowed to distinguish tocochromanols from matrix components with similar Rf values. In most cases, determined vitamin E contents matched well with the information listed on the label of the investigated DSC samples. The method is fast, easy to perform and gently treats the analytes as it requires no thermal treatment prior to quantification, which makes it suitable as a screening method.
Sterols in fresh and preserved button mushroom (Agaricus bisporus) products
(2025) Sommer, Katrin; Vetter, Walter
Mushrooms are highly valued but also very perishable foods. As a consequence, various types of preserved mushroom products are available in retail stores. Common preservation techniques include pickling in brine and drying. Such processes might cause a partial transformation of unstable products like ergosterol, which is the most relevant sterol in mushrooms. In this study, gas chromatography with mass spectrometry (GC/MS) was used to examine the levels of ergosterol and other, lower abundant sterols in dried and pickled button mushrooms ( Agaricus bisporus ) from German retail. Multivariate analysis of the free sterol fraction was used to verify significantly lower ergosterol contents in the preserved products (pickled: 280 ± 30 mg/100 g dry weight, dried: 190 ± 20 mg/100 g dry weight) compared to fresh button mushrooms (610 ± 20 mg/100 g dry weight). In addition, the contribution of ergosterol to the total sterol content in dried button mushroom samples (84 ± 1%) was comparable to fresh samples (87 ± 1%) but significantly lower in the pickled products (78 ± 1%). Storage experiments with pure ergosterol standards in solution indicated a full degradation of ergosterol and the formation of seven transformation products at room temperature storage within 9 days.
Valuable furan fatty acids in soybeans and soy products
(2020) Müller, Franziska; Hogg, Melanie; Vetter, Walter
Furan fatty acids (FuFAs) are valuable minor compounds in our food with excellent antioxidant properties. Naturally occurring FuFAs are characterised by a central furan moiety with one or two methyl groups in β-/β’-position of the heterocycle (monomethyl- or M-FuFAs and dimethyl- or D-FuFAs). Comparably high concentrations of D-/M-FuFAs were reported in soybeans, but soy is often consumed as a processed product, such as full-fat soy flour and flakes, soy drink, tofu and texturised soy protein (TSP). Due to the chemical lability of D-/M-FuFAs, e.g. in the presence of light or oxygen, a degradation during the processing is possible. For this purpose, freshly harvested soybeans (n = 4) and differently processed soybean products (n = 22) were analysed on FuFAs. Three FuFAs, i.e. 11-(3,4-dimethyl-5-pentylfuran-2-yl)-undecanoic acid (11D5), 9-(3,4-dimethyl-5-pentylfuran-2-yl)-nonanoic acid (9D5), and 9-(3-methyl-5-pentylfuran-2-yl)-nonanoic acid (9M5), were identified and quantified in all fresh soybeans and most of the processed soy products (n = 20). A trend towards lower D-/M-FuFA contents in higher processed products was observable. Lower FuFA concentrations were usually accompanied with a decrease of the share of the less stable D-FuFAs (9D5, 11D5) in favour of the M-FuFA 9M5. Furthermore, one or two 3,4-nonmethylated furan fatty acids (N-FuFAs), i.e. 8-(5-hexylfuran-2-yl)-octanoic acid (8F6) and partly 7-(5-heptylfuran-2-yl)-heptanoic acid (7F7), were detected in all processed products, but not in the freshly harvested soybeans. Our results indicate that D-/M-/N-FuFAs may serve as suitable markers for both, careful manufacturing processes and adequate storage conditions of soy products.

Browse

Browsing Institut für Lebensmittelchemie by Journal "European food research and technology"