A ternary system of α-tocopherol with phosphatidylethanolamine and l-ascorbyl palmitate in bulk oils provides antioxidant synergy through stabilization and regeneration of α-tocopherol.

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 α-tocopherol (α-Toc) was investigated in an ethyl linoleate model and sunflower oil at 110 °C.

Formation of Secondary and Tertiary Volatile Compounds Resulting from the Lipid Oxidation of Rapeseed Oil.

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.

Influence of the Carboxylic Function on the Degradation of d-Galacturonic Acid and Its Polymers.

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 CO during the heat treatment of uronic acids.

The Formation of Methyl Ketones during Lipid Oxidation at Elevated Temperatures.

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.

Development and validation of a liquid chromatography-mass spectrometry method for simultaneous analysis of triazine-based brominated flame retardants in environmental samples.

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).

Basic Structure of Melanoidins Formed in the Maillard Reaction of 3-Deoxyglucosone and γ-Aminobutyric Acid.

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.

1,3,5-Tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione: kinetic studies and phototransformation products.

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.

Effect of Different Drying Methods on Nutrient Quality of the Yellow Mealworm ( L.).

Yellow mealworm ( 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.

2-Deoxyglucosone: A New C-α-Dicarbonyl Compound in the Maillard Reaction of d-Fructose with γ-Aminobutyric Acid.

In this study, α-dicarbonyl compounds consisting of a backbone with six carbon atoms resulting from the Maillard reaction of d-fructose with γ-aminobutyric acid were determined. The reaction was carried out under mild reaction conditions at 50 °C and water contents between 0 and 90%. A thus far unknown α-dicarbonyl compound was found as the main product in the first 24 h at water contents below 50%.

Formation of Phenolic Compounds from d-Galacturonic Acid.

Aqueous d-galacturonic acid (d-GalA) model systems treated at 130 °C at different pH values show an intense color formation, whereas other reducing sugars, such as d-galactose (d-Gal), scarcely react. GC-MS measurements revealed the presence of several phenolic compounds: e.g.

NMR analyses of complex d-glucose anomerization.

Analyzing the H NMR spectrum of d-glucose, the resonance frequencies of the anomeric protons of five d-glucose anomers could be determined in dependence on temperature. Besides, the relative concentrations of all cyclic d-glucose anomers could be quantified. Based on that, thermodynamic parameters were calculated.

General acid/base catalysis of sugar anomerization.

Based on theoretical and mechanistical considerations, an equation is presented that describes the observed rate of a pH sensitive reaction. In contrast to the commonly used catalytic catenary, the new approach enables the calculation of non-biased thermodynamic activation parameters. Applying this model, the general acid/base catalysis of the ring opening of β-d-fructopyranose was analyzed polarimetrically.

The major glucosinolate hydrolysis product in rocket (Eruca sativa L.), sativin, is 1,3-thiazepane-2-thione: Elucidation of structure, bioactivity, and stability compared to other rocket isothiocyanates.

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.

Assessment of the bacterial impact on the post-mortem formation of zinc protoporphyrin IX in pork meat.

The post-mortem accumulation of the heme biosynthesis metabolite zinc protoporphyrin IX (ZnPP) in porcine muscle is associated with both a meat-inherent and a bacterial enzymatic reaction during meat storage. To estimate the bacterial impact on ZnPP formation, meat and meat-like media were investigated by HPLC-FLD (and MALDI-TOF-MS) after inoculation with a representative microorganism (P. fluorescens).

Investigating the causes of low detectability of pesticides in fruits and vegetables analysed by high-performance liquid chromatography - Time-of-flight.

Because of the high number of possible pesticide residues and their chemical complexity, it is necessary to develop methods which cover a broad range of pesticides. In this work, a qualitative multi-screening method for pesticides was developed by use of HPLC-ESI-Q-TOF. 110 pesticides were chosen for the creation of a personal compound database and library (PCDL).

Simultaneous formation of 3-deoxy-d-threo-hexo-2-ulose and 3-deoxy-d-erythro-hexo-2-ulose during the degradation of d-glucose derived Amadori rearrangement products: Mechanistic considerations.

Analyzing classical model reaction systems of Amadori rearrangement products (ARP) it became apparent that the formation of 3-deoxy-d-threo-hexo-2-ulose (3-deoxygalactosone, 3-DGal) during the degradation of ARPs is highly dependent on pH and the amino acid residue of the respective ARP. Based on a detailed analysis of the NMR chemical shifts of the sugar moieties of different ARPs, it could be derived that the formation of 3-DGal is sensitive to the stability of a co-operative hydrogen bond network which involves HO-C3, the deprotonated carboxyl functionality and the protonated amino nitrogen of the amino acid substituent. Participating in this bond network, HO-C3 is partially protonated which facilitates the elimination of water at C3.

Brassica vegetables as sources of epithionitriles: Novel secondary products formed during cooking.

The epithionitriles, 1-cyano-2,3-epithiopropane, in particular, and 1-cyano-3,4-epithiobutane, are important, but yet underestimated glucosinolate hydrolysis products that are released instead of the cancer preventative isothiocyanates in Brassica vegetables, such as cabbage, broccoli, or pak choi. Here, we characterized the reactivity of 1-cyano-2,3-epithiopropane under aqueous heat treatment conditions and compared our findings to those of the related epithionitriles 1-cyano-3,4-epithiobutane and 1-cyano-4,5-epithiopentane. In contrast to the other epithionitriles, 1-cyano-2,3-epithiopropane is highly reactive.

Formation of Reactive Intermediates, Color, and Antioxidant Activity in the Maillard Reaction of Maltose in Comparison to d-Glucose.

In this study, the Maillard reaction of maltose and d-glucose in the presence of l-alanine was investigated in aqueous solution at 130 °C and pH 5. The reactivity of both carbohydrates was compared in regards of their degradation, browning, and antioxidant activity. In order to identify relevant differences in the reaction pathways, the concentrations of selected intermediates such as 1,2-dicarbonyl compounds, furans, furanones, and pyranones were determined.

Influence of l-pyroglutamic acid on the color formation process of non-enzymatic browning reactions.

Heating aqueous d-glucose model reactions with l-glutamine and l-alanine yielded similar colored solutions. However, size-exclusion chromatography (SEC) revealed that both non-enzymatic browning reactions proceeded differently. Due to a fast occurring cyclization of l-glutamine to pyroglutamic acid, the typical amino-carbonyl reaction was slowed down.

Browning Potential of C-α-Dicarbonyl Compounds under Maillard Conditions.

In this work, the three major C-α-dicarbonyl compounds glucosone (GLUC), 1-deoxyglucosone (1-DG), and 3-deoxyglucosone (3-DG) were synthesized and examined under Maillard conditions (aqueous solutions with the addition of l-alanine at 130 °C and pH 5/8). For the first time, the resulting color formation, antioxidant activity, and generation of short-chained α-dicarbonyls were investigated and compared to incubations of d-glucose and d-fructose. An additive effect on the formation of color, an antagonistic effect on the generation of α-dicarbonyl compounds, and a synergistic effect on the antioxidant activity could be observed for the 1-DG/GLUC combination.

Antioxidant Properties of Heterocyclic Intermediates of the Maillard Reaction and Structurally Related Compounds.

It is well established that a wide range of reductones is formed in the course of the Maillard reaction and that these substances contribute to the oxidative stability of food. The aim of this study was to analyze 12 important heterocyclic intermediates with and without reductone structure as well as structurally related substances under equal conditions to compare their antioxidant properties in detail. For this purpose, five methods were selected including photometrical methods such as the trolox equivalent antioxidant capacity assay and an electron paramagnetic resonance spectroscopic method.

Technological characteristics and selected bioactive compounds of Opuntia dillenii cactus fruit juice following the impact of pulsed electric field pre-treatment.

Selected technological characteristics and bioactive compounds of juice pressed directly from the mash of whole Opuntia dillenii cactus fruits have been investigated. The impact of pulsed electric fields (PEF) for a non-thermal disintegration on the important juice characteristics has been evaluated in comparison to microwave heating and use of pectinases. Results showed that the cactus juice exhibited desirable technological characteristics.

Structure-reactivity relationship of Amadori rearrangement products compared to related ketoses.

Structure-reactivity relationships of Amadori rearrangement products compared to their related ketoses were derived from multiple NMR spectroscopic techniques. Besides structure elucidation of six Amadori rearrangement products derived from d-glucose and d-galactose with l-alanine, l-phenylalanine and l-proline, especially quantitative (13)C selective saturation transfer NMR spectroscopy was applied to deduce information on isomeric systems. It could be shown exemplarily that the Amadori compound N-(1-deoxy-d-fructos-1-yl)-l-proline exhibits much higher isomerisation rates than d-fructose, which can be explained by C-1 substituent mediated intramolecular catalysis.

Model Studies on the Antioxidative Effect of Polyphenols in Thermally Treated D-Glucose/L-Alanine Solutions with Added Metal Ions.

The influence of different polyphenolic compounds (PPs) on the Maillard reaction in a d-glucose/l-alanine model system with or without metal ions was studied under various reaction conditions. At temperatures up to 100 °C the PPs showed pro-oxidative effects due to their reducing effects on metal ions. This can be explained by a combined redox cycling mechanism of metals and PPs that promotes oxidation in the Maillard reaction.