LebensmittelchemieVolume 78, Issue S1 p. S1-125-S1-125 Abstract Methylketone – flüchtige Verbindungen aus der Lipidperoxidation S. Grebenteuch, Corresponding Author S. Grebenteuch [email protected] Technische Universität Berlin, Fachgebiet Lebensmittelchemie und Analytik, Berlin/D Institut für Lebensmittel- und Umweltforschung e.V. (ILU), Bad Belzig/D[email protected]Search for more papers by this authorL. W. Kroh, L. W. Kroh Technische Universität Berlin, Fachgebiet Lebensmittelchemie und Analytik, Berlin/DSearch for more papers by this authorS. Rohn, S. Rohn Technische Universität Berlin, Fachgebiet Lebensmittelchemie und Analytik, Berlin/D Institut für Lebensmittel- und Umweltforschung e.V. (ILU), Bad Belzig/DSearch for more papers by this author S. Grebenteuch, Corresponding Author S. Grebenteuch [email protected] Technische Universität Berlin, Fachgebiet Lebensmittelchemie und Analytik, Berlin/D Institut für Lebensmittel- und Umweltforschung e.V. (ILU), Bad Belzig/D[email protected]Search for more papers by this authorL. W. Kroh, L. W. Kroh Technische Universität Berlin, Fachgebiet Lebensmittelchemie und Analytik, Berlin/DSearch for more papers by this authorS. Rohn, S. Rohn Technische Universität Berlin, Fachgebiet Lebensmittelchemie und Analytik, Berlin/D Institut für Lebensmittel- und Umweltforschung e.V. (ILU), Bad Belzig/DSearch for more papers by this author First published: 01 March 2024 https://doi.org/10.1002/lemi.202452095AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Quellen 1Grebenteuch S.,Kanzler C., Klaußnitzer, S.; Kroh, L.W., Rohn S., The Formation of Methyl Ketones during Lipid Oxidation at Elevated Temperatures. Molecules 2021 26, 1104. https://doi.org/10.3390/molecules26041104 10.3390/molecules26041104 PubMedWeb of Science®Google Scholar Volume78, IssueS1Supplement: Abstracts der Vorträge der Regionalverbände und die der Posterflashtalks der AG JLCMarch/April 2024Pages S1-125-S1-125 ReferencesRelatedInformation

LebensmittelchemieVolume 77, Issue S3 p. S3-026-S3-026 Vorträe Neue Reaktionswege in der Lipidoxidation - Bildung von aromaaktiven Methylketonen S. Grebenteuch, S. Grebenteuch Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin/D Institut für Lebensmittel- und Umweltforschung e.V. (ILU), Papendorfer Weg 3, 14806 Bad BelzigSearch for more papers by this authorJula Buhmann, Jula Buhmann Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this authorL. W. Kroh, L. W. Kroh Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this authorS. Rohn, S. Rohn Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin/D Institut für Lebensmittel- und Umweltforschung e.V. (ILU), Papendorfer Weg 3, 14806 Bad BelzigSearch for more papers by this author S. Grebenteuch, S. Grebenteuch Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin/D Institut für Lebensmittel- und Umweltforschung e.V. (ILU), Papendorfer Weg 3, 14806 Bad BelzigSearch for more papers by this authorJula Buhmann, Jula Buhmann Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this authorL. W. Kroh, L. W. Kroh Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this authorS. Rohn, S. Rohn Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin/D Institut für Lebensmittel- und Umweltforschung e.V. (ILU), Papendorfer Weg 3, 14806 Bad BelzigSearch for more papers by this author First published: 01 August 2023 https://doi.org/10.1002/lemi.202359022AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Referenzen [1]van Boekel et al. Mol. Nutr. Food Res. 2010, 54, 1215–1247. [2]Jacobsen Oxidation in Foods and Beverages and Antioxidant Applications 2010, 122–142. [3]Frankel Lipid Oxidation: Oily Press Lipid Library Series, 2012, 67–98. Volume77, IssueS3Supplement: Abstracts der Vorträge, Posterflashtalks und Poster von den 51. Deutschen Lebensmittelchemietagen 2023August 2023Pages S3-026-S3-026 ReferencesRelatedInformation

The stabilization of fats and oils against oxidative lipid deterioration is still a great challenge. The synergistic interaction between phospholipids, L-ascorbate, and tocopherols have not yet been comprehensively understood. The mechanism of the synergistic antioxidant effect of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (PE) in mixtures with L-ascorbyl palmitate (AP) and alpha-tocopherol (alpha-Toc) was investigated in an ethyl linoleate model and sunflower oil at 110 C. The mixture of PE, AP, and alpha-Toc is stabilized through continuous regeneration of alpha-Toc from its oxidation product alpha-tocopherylquinone (alpha-TQ). This reaction is catalyzed by acids and proceeded through the formation of the alpha-tocopherone ion (T+) as an intermediate product. In addition to the direct reduction of T+ by AP, PE can also cause regeneration indirectly by reacting with dehydroascorbyl palmitate (DHAP) or other tricarbonyl compounds to form amino reductones. PE and AP undergo an amino-carbonyl reaction to form the condensate PE(AP)2.

The lipid oxidation of fats and oils leads to volatile organic compounds, having a decisive influence on the sensory quality of foods. To understand formation and degradation pathways and to evaluate the suitability of lipid-derived aldehydes as marker substances for the oxidative status of foods, the formation of secondary and tertiary lipid oxidation compounds was investigated with gas chromatography in rapeseed oils. After 120 min, up to 65 compounds were detected. In addition to secondary degradation products, tertiary products such as alkyl furans, ketones, and aldol condensation products were also found. The comparison of rapeseed oils, differing in their initial peroxide values, showed that the formation rate of secondary compounds was higher in pre-damaged oils. Simultaneously, a faster degradation, especially of unsaturated aldehydes, was observed. Consequently, the formation of tertiary products (e.g., alkyl furans, aldol adducts) from well-known lipid oxidation products (i.e., propanal, hexanal, 2-hexenal, and 2-nonenal) was investigated in model systems. The experiments showed that these compounds form the new substances in subsequent reactions, especially, when other compounds such as phospholipids are present. Hexanal and propanal are suitable as marker compounds in the early phase of lipid oxidation, but at an advanced stage they are subject to aldol condensation. Consequently, the detection of tertiary degradation products needs to be considered in advanced lipid oxidation.

LebensmittelchemieVolume 75, Issue S2 p. S077-S077 Poster Reaktionen zwischen sekundären Lipidoxidationsprodukten und Zuckerabbauprodukten S. Grebenteuch, S. Grebenteuch Berlin/DSearch for more papers by this authorS. Klaußnitzer, S. Klaußnitzer Berlin/DSearch for more papers by this authorL. W. Kroh, L. W. Kroh Berlin/DSearch for more papers by this authorProf. Dr. S. Rohn, Prof. Dr. S. Rohn Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this author S. Grebenteuch, S. Grebenteuch Berlin/DSearch for more papers by this authorS. Klaußnitzer, S. Klaußnitzer Berlin/DSearch for more papers by this authorL. W. Kroh, L. W. Kroh Berlin/DSearch for more papers by this authorProf. Dr. S. Rohn, Prof. Dr. S. Rohn Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this author First published: 30 August 2021 https://doi.org/10.1002/lemi.202158078AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume75, IssueS2Supplement: Vorträge und Poster des 49. Deutschen LebensmittelchemikertagsAugust/September 2021Pages S077-S077 RelatedInformation

Lipid oxidation and the resulting volatile organic compounds are the main reasons for a loss of food quality. In addition to typical compounds, such as alkanes, aldehydes and alcohols, methyl ketones like heptan-2-one, are repeatedly described as aroma-active substances in various foods. However, it is not yet clear from which precursors methyl ketones are formed and what influence amino compounds have on the formation mechanism. In this study, the formation of methyl ketones in selected food-relevant fats and oils, as well as in model systems with linoleic acid or pure secondary degradation products (alka-2,4-dienals, alken-2-als, hexanal, and 2-butyloct-2-enal), has been investigated. Elevated temperatures were chosen for simulating processing conditions such as baking, frying, or deep-frying. Up to seven methyl ketones in milk fat, vegetable oils, and selected model systems have been determined using static headspace gas chromatography-mass spectrometry (GC-MS). This study showed that methyl ketones are tertiary lipid oxidation products, as they are derived from secondary degradation products such as deca-2,4-dienal and oct-2-enal. The study further showed that the position of the double bond in the precursor compound determines the chain length of the methyl ketone and that amino compounds promote the formation of methyl ketones to a different degree. These compounds influence the profile of the products formed. As food naturally contains lipids as well as amino compounds, the proposed pathways are relevant for the formation of aroma-active methyl ketones in food.

Past investigations have shown high browning potential during the caramelization of sugar acids in comparison to reducing sugars. However, no approaches to elucidate the chemical mechanisms have been made. Therefore, this study aims to clarify the reasons for the high browning potential by measuring the mutarotation velocity and the elimination of CO2 during the heat treatment of uronic acids. Performed polarimetric experiments show that the mutarotation velocity of d-galacturonic acid exceeds that of d-galactose by a factor of nearly 4.5. However, the ring opening velocity is not the only parameter that differs between the two carbohydrate structures. Measurements of the release of CO2 of heated d-galacturonic acid at 60 °C show a steady increase, and after 48 h, 6% of degraded d-galacturonic acid has eliminated CO2. CO2 release was also found during the heating of pectin, indicating a decarboxylation reaction during thermal degradation. One of the degradation reactions postulated for the release of CO2 leads to α-ketoglutaraldehyde, which is responsible for the formation of several chromophoric substances.

In the present study, a novel and reliable analytical method was developed and validated for the simultaneous determination of 1,3,5-tris(2,3-dibromopropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TDBP-TAZTO) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) in environmental samples using high-performance liquid chromatography coupled to a tandem mass spectrometer. Firstly, for optimization of the liquid chromatography separation, mobile phases, oven temperatures, modifiers, and buffers were varied. Afterwards, the extraction efficiency of sediment and fish samples was tested with different techniques (pressurized liquid, solid-liquid, ultrasound-assisted, and Soxhlet extraction). Additionally, cleanup using modified multilayer silica gel (sediment) and gel permeation chromatography as well as Florisil® columns (fish) with several solvent mixtures were performed. The best results were obtained with the pressurized liquid extraction (optimal conditions: extraction solvent 100% toluene, extraction time 20 min, cycles two, extraction temperature 100 °C, and flushing volume 60%) compared to other solvent extraction methods. On the basis of this optimized analytical procedure, the method was validated with satisfactory values of correlation coefficient (R2) between 0.998 and 0.999 for both matrices in the calibration range of 2.0–502.0 μg kg−1 for TDBP-TAZTO and 16.6–770.6 μg kg−1 for TTBP-TAZ in sediment samples as well as 4.8–303.5 μg kg−1 and 47.4–742.5 μg kg−1 in fish samples (bream), respectively. Mean recoveries (n = 5) were calculated for both analytes with spiked matrices at one concentration level (100 μg kg−1) between 98 and 114% with intra-day relative standard deviations less than 11%. The inter-day precision (n = 15) was also acceptable for both compounds < 11%. It was found that the limit of detection and limit of quantification were in the range of 0.4–1.3 μg kg−1 for TDBP-TAZTO and 10–28 μg kg−1 for TTBP-TAZ in surface sediment samples and 7–25 μg kg−1 and 22–80 μg kg−1 in fish samples (bream), respectively. The results indicated that these analytical methods could provide reliable and efficient approaches for quantification of TDBP-TAZTO and TTBP-TAZ in sediment and fish samples.

Thermal degradation of modified pectin samples with varying molecular structure during storage was recently studied at 60 degrees C and 80% relative humidity (rh) for 28 days. Demethoxylation and depolymerisation were identified as main degradation reactions. The present paper aims on improving the understanding of the different depolymerisation reactions and their interplay with demethoxylation during storage. Therefore, thermal degradaton of acidic and alkaline demethoxylated pectins was studied at a further reduced rh of 40%. The alterations were examined in detail via molecular parameters and were reflected by differential scanning calorimetry and attenuated total reflectance Fourier-transformation infrared spectroscopy. The impact of thermal degradation on pectin particle structure was studied via particle surface area and microscopy. At low relative humidity (rh) demethoxylation and depolymerisation were reduced, and the formation of brown reaction products, resulting from further decomposition of intermediate uronides and neutral sugars, was restricted. By comparing thermal degradation at different humidity, eliminative decarboxylation was identified as the main depolymerisation reaction. Reduction of rh affected also the alteration of pectin material properties, particle surface reduction was less pronounced. Molecular alterations were stronger in case of acidic demethoxylated samples, and alterations of material properties were higher in case of alkaline demethoxylated samples.

Melanoidins are formed in foods during processing through the Maillard reaction between carbohydrates and amino compounds. The aim of this study was to draw conclusions about the formation mechanism and the structure of melanoidins formed at low water contents and low temperatures. In the Maillard reaction of d-glucose and γ-aminobutyric acid at low water contents 3-deoxyglucosone is the most important intermediate. Therefore, we used the reaction of 3-deoxyglucosone with γ-aminobutyric acid or β-alanine as a simplified model system. The degradation of 3-deoxyglucosone and the color formation of the formed melanoidins were determined. In addition, the reaction mixture was analyzed with high-resolution mass spectrometry and a Kendrick analysis was applied. Oligomers consisting of up to four molecules of 3-deoxyglucosone and three amino acids and their respective dehydration products with furanoidic structure were detected. The melanoidin structure of C-C linked monomeric units postulated by Kroh et al. could be confirmed.

In this study, the thermal decomposition of 1,3,5-tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione (TDBPTAZTO) and 2,4,6-tris-(2,4,6-tribromo-phenoxy)-1,3,5-triazine (TTBP-TAZ) were investigated for the first time by thermogravimetric analysis. Both compounds were thermal degraded between 225 and 350 degrees C (TDBP-TAZTO) as well as 300 and 400 degrees C (TTBP-TAZ). As a result, mass loss (%) of 98.5% for TTBP-TAZ and 95.4% for TDBP-TAZTO at 600 degrees C under N-2 were observed. The major pyrolytic degradation products of TTBP-TAZ were formed in a single step and identified by FTIR analysis as 2,4,6-tribromophenol and further bromine-substituted aromatic compounds. In comparison, TDBP-TAZTO was pyrolytic degraded in two steps, whereby on the first step the release of hydrogen bromide and 1,3,5-triallyl-1,3,5-triazine-2,4,6-trione could be detected. In the second minor step, isocyanic acid could be additionally identified. Subsequently, the obtained products of the TGA-FTIR measurements were used for a targeted search for mass fragments in mass spectrometry measurements. For TTBP-TAZ, only the degradation product 1,3,5-tribromobenzene could be detected by MS/MS analyzes. No comparable thermal degradation products, except hydrogen bromide, were observed in the MS/MS spectra of TDBP-TAZTO. Therefore, the search of further mass fragments was not possible compared to the findings of the TGA-FTIR measurements.

Yellow mealworm (Tenebrio molitor L.) represents a sustainable source of proteins and fatty acids for feed and food. Industrial production of mealworms necessitates optimized processing techniques, where drying as the first postharvest procedure is of utmost importance for the quality of the final product. This study examines the nutritional quality of mealworm larvae processed by rack oven drying, vacuum drying or freeze drying, respectively. Proximate composition and fatty acid profile were comparable between the dried larvae. In contrast, larvae color impressions and volatile compound profiles were very much dependent on processing procedure. High-temperature rack oven drying caused pronounced darkening with rather low content of volatiles, pointing toward the progress of Maillard reaction. On the other hand, vacuum drying or freeze drying led to enrichment of volatile Maillard reaction and lipid oxidation intermediates, whose actual sensory relevance needs to be clarified in the future. Beyond sensory and visual importance drying intermediates have to be considered with regard to their metal ion chelating ability; in particular for essential trace elements such as Zn2+. This study found comparable total zinc contents for the differently dried mealworm samples. However, dried larvae, in particular after rack oven drying, had only low zinc accessibility, which was between 20% and 40%. Therefore, bioaccessibility rather than total zinc has to be considered when their contribution to meeting the nutritional requirements for zinc in humans and animals is evaluated.

1,3,5-Tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione (TDBP-TAZTO) is an emerging brominated flame retardant which is widely used in several plastic materials (electric and electronic equipment, musical instruments, automotive components). However, until today, no photochemical studies as well as the identification of possible phototransformation products (PTPs) were described in literature. Therefore, in this study, UV-(C) and simulated sunlight irradiation experiments were performed to investigate the photolytic degradation of TDBP-TAZTO and to identify relevant PTPs for the first time. The UV-(C) irradiation experiments show that the photolysis reaction follows a first-order kinetic model. Based on this, the photolysis rate constant k as well as the half-life time t1/2 were calculated to be k = (41 ± 5 × 10−3) min−1 and t1/2 = (17 ± 2) min. In comparison, a minor degradation of TDBP-TAZTO and no formed phototransformation products were obtained under simulated sunlight. In order to clarify the photochemical behavior, different chemicals were added to investigate the influence on indirect photolysis: (i) H2O2 for generation of hydroxyl radicals and (ii) two quenchers (2-propanol, sodium azide) for scavenging oxygen species which were formed during the irradiation experiments. Herein, nine previously unknown PTPs of TDBP-TAZTO were detected under UV-(C) irradiation and identified by HPLC-(HR)MS. As a result, debromination, hydroxylation, and dehydrobromination reactions could be presumed as the main degradation pathways by high-resolution mass spectrometry. The direct as well as the OH radical-induced indirect photolysis were observed.

LebensmittelchemieVolume 73, Issue S1 p. S057-S057 Chemische Reaktionen in Lebensmitteln (CRL) Oligomerbildung von flüchtigen Verbindungen aus der Lipidoxidation F. M. Kabisch, F. M. Kabisch Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Fachgebiet Lebensmittelchemie und Analytik, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this authorS. Grebenteuch, S. Grebenteuch Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Fachgebiet Lebensmittelchemie und Analytik, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this authorL. W. Kroh, L. W. Kroh Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Fachgebiet Lebensmittelchemie und Analytik, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this author F. M. Kabisch, F. M. Kabisch Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Fachgebiet Lebensmittelchemie und Analytik, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this authorS. Grebenteuch, S. Grebenteuch Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Fachgebiet Lebensmittelchemie und Analytik, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this authorL. W. Kroh, L. W. Kroh Technische Universität Berlin, Institut für Lebensmitteltechnologie und Lebensmittelchemie, Fachgebiet Lebensmittelchemie und Analytik, Gustav-Meyer-Allee 25, 13355 Berlin/DSearch for more papers by this author First published: 05 May 2020 https://doi.org/10.1002/lemi.201951057AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume73, IssueS1Supplement: 48. Deutscher LebensmittelchemikertagSeptember 2019Pages S057-S057 RelatedInformation

Pectin powder is degraded during storage and transport by demethoxylation and depolymerisation. The degradation mechanisms and especially the influence of pre-treatments on the degradation reactions are not completely understood. In this study, commercial citrus pectin was modified by either acidic or alkaline demethoxylation. The modified pectins, as well as the commercial pectin, were thermally degraded during four weeks of storage at 60 degrees C and 80% relative humidity. Demethoxylation and depolymerisation as well as colour alterations were examined during degradation, and the course of the reactions was monitored. It was found that the type of pre-treatment during modification determined the material properties and, thus, the water uptake of the modified pectin powders. The resulting water availability in the samples was crucial to the extent of demethoxylation and to the type and intensity of depolymerisation since some of these reactions competed for the water in the climate chamber. The pre-treatment also determined the content of neutral sugars and sodium ions of the modified pectins. High contents of these components limited the extent of degradation in different ways. A previously assumed third depolymerisation mechanism of pectins, beside backbone hydrolysis and beta-elimination, was confirmed. (C) 2018 Elsevier Ltd. All rights reserved.

Rocket is rich in glucosinolates and valued for its hot and spicy taste. Here we report the structure elucidation, bioactivity, and stability of the mainly formed glucosinolate hydrolysis product, namely sativin, which was formerly thought to be 4-mercaptobutyl isothiocyanate. However, by NMR characterization we revealed that sativin is in fact 1,3-thiazepane-2-thione, a tautomer of 4-mercaptobutyl isothiocyanate with 7-membered ring structure and so far unknown. This finding was further substantiated by conformation sampling using molecular modeling and total enthalpy calculation with density functional theory. During aqueous heat treatment sativin in general was quite stable, while the isothiocyanates erucin and sulforaphane were labile, having half-lives of 132 min and 56 min (pH 5, 100 degrees C), respectively. Moreover, using a WST-1 assay, we found that sativin did not reduce cell viability of HepG2 cells in a range of 0.3-30 mu M, and, therefore, exhibited no cytotoxic effects in this cell line.