Співвідношення прямої мови та слів автора в художній німецькомовній прозі

Стилістична картина художнього твору, а також стилістичний потенціал прямої мови багато в чому залежать від того, у якому кількісному та структурному співвідношенні перебувають мова оповідача і мова персонажів. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/1773

Revealing the main factors and two-way interactions contributing to food discolouration caused by iron-catechol complexation

Fortification of food with iron is considered to be an effective approach to counter the global health problem caused by iron deficiency. However, reactivity of iron with the catechol moiety of food phenolics leads to discolouration and impairs bioavailability. In this study, we investigated the interplay between intrinsic and extrinsic factors on food discolouration caused by iron-catechol complexation. To this end, a three-level fractional factorial design was implemented. Absorbance spectra were analysed using statistical methods, including PCA, HCA, and ANOVA. Furthermore, a direct link between absorbance spectra and stoichiometry of the iron-catechol complexes was confirmed by ESI-Q-TOF-MS. All statistical methods confirm that the main effects affecting discolouration were type of iron salt, pH, and temperature. Additionally, several two-way interactions, such as type of iron salt × pH, pH × temperature, and type of iron salt × concentration significantly affected iron-catechol complexation. Our findings provide insight into iron-phenolic complexation-mediated discolouration, and facilitate the design of iron-fortified foods.</p

Unravelling discolouration caused by iron-flavonoid interactions: Complexation, oxidation, and formation of networks

Iron-flavonoid interactions in iron-fortified foods lead to undesirable discolouration. This study aimed to investigate iron-mediated complexation, oxidation, and resulting discolouration of flavonoids by spectrophotometric and mass spectrometric techniques. At pH 6.5, iron complexation to the 3–4 or 4–5 site instantly resulted in bathochromic shifting of the π → π* transition bands, and complexation to the 3ʹ-4ʹ site (i.e. catechol moiety) induced a π → dπ transition band. Over time, iron-mediated oxidative degradation and coupling reactions led to the formation of hydroxybenzoic acid derivatives and dehydrodimers, respectively resulting in a decrease or increase in discolouration. Additionally, we employed XRD, SEM, and TEM to reveal the formation of insoluble black metal-phenolic networks (MPNs). This integrated study on iron-mediated complexation and oxidation of flavonoids showed that the presence of the C2–C3 double bond in combination with the catechol moiety and either the 4-carbonyl or 3-hydroxyl increased the intensity of discolouration, extent of oxidation, and formation of MPNs

Bacterial lipoxygenases: Biochemical characteristics, molecular structure and potential applications

Lipoxygenases (LOXs) are enzymes that catalyze dioxygenation of polyunsaturated fatty acids into fatty acid hydroperoxides. The formed fatty acid hydroperoxides are of interest as they can readily be transformed to a number of value-added compounds. LOXs are widely distributed in both eukaryotic and prokaryotic organisms, including humans, animals, plants, fungi and bacteria. Compared to eukaryotic enzymes, bacterial enzymes are typically easier to produce at industrial scale in a heterologous host. However, many bacterial LOXs were only identified relatively recently and their structure and biochemical characteristics have not been extensively studied. A better understanding of bacterial LOXs' structure and characteristics will lead to the wider application of these enzymes in industrial processes. This review focuses on recent findings on the biochemical characteristics of bacterial LOXs in relation to their molecular structure. The basis of LOX catalysis as well as emerging determinants explaining the regio- and enantioselectivity of different LOXs are also summarized and critically reviewed. Clustering and phylogenetic analyses of bacterial LOX sequences were performed. Finally, the improvement of bacterial LOXs by mutagenesis approaches and their application in chemical synthesis are discussed

Interaction of iron(III) with taste enhancers: Potential of Fe(III) salts with inosine monophosphate or guanosine monophosphate for food fortification

Iron interactions in iron-fortified savory concentrates lead to undesirable discoloration, even when poorly-water soluble iron salts such as ferric pyrophosphate (Fe4PP3) are used. This is the first study to comprehensively investigate the interaction of Fe(III) with three common taste enhancers: glutamate (Glu), inosine monophosphate (IMP), and guanosine monophosphate (GMP). The stability of the complexes of Fe(III) with IMP or GMP is higher compared to that with Glu. Neutrality of IMP or GMP species with Fe(III) at pH 3–8 resulted in precipitation. This property was exploited to synthesize Fe(III) salts of IMP or GMP (i.e. Fe2IMP3 and Fe2GMP3) by aqueous chemical precipitation. Iron dissolution from Fe2IMP3 and Fe2GMP3 was up to twenty-fold higher at gastric pH (1–3), indicative of better bio-accessibility, and up to fifteen-fold lower at food pH (3–7), indicative of decreased reactivity in food, compared to Fe4PP3. Consequently, Fe2IMP3 and Fe2GMP3, compared to Fe4PP3, led to less discoloration in combination with the poorly soluble phenolics that are commonly present in savory concentrates. We conclude that Fe(III) salts of IMP or GMP can potentially serve as iron fortificants due to their increased solubility at gastric pH (1–3), decreased iron dissolution at food pH (3–7), and decreased reactivity at food pH

Interactions of Natural Flavones with Iron Are Affected by 7-O-Glycosylation, but Not by Additional 6″-O-Acylation

In iron-fortified bouillon, reactivity of the iron ion with (acylated) flavone glycosides from herbs can affect product color and bioavailability of iron. This study investigates the influence of 7-O-glycosylation and additional 6″-O-acetylation or 6″-O-malonylation of flavones on their interaction with iron. Nine (6″-O-acylated) flavone 7-O-apiosylglucosides were purified from celery (Apium graveolens), and their structures were elucidated by mass spectrometry (MS) and nuclear magnetic resonance (NMR). In the presence of iron, a bathochromic shift and darker color were observed for the 7-O-apiosylglucosides compared to the aglycon of flavones that only possess the 4-5 site. Thus, the ability of iron to coordinate to the flavone 4-5 site is increased by 7-O-glycosylation. For flavones with an additional 3′-4′ site, less discoloration was observed for the 7-O-apiosylglucoside compared to the aglycon. Additional 6″-O-acylation did not affect the color. These findings indicate that model systems used to study discoloration in iron-fortified foods should also comprise (acylated) glycosides of flavonoids

Design and characterization of Ca-Fe(III) pyrophosphate salts with tunable pH-dependent solubility for dual-fortification of foods

Food-fortification using poorly water-soluble mineral-containing compounds is a common approach to deliver iron. However, it comes with the challenge of ensuring iron bio-accessibility and limiting iron-phenolic interactions that can change organoleptic properties. Mixed Ca-Fe(III) pyrophosphate salts with the general formula Ca2(1-x)Fe4x(P2O7)(1+2x) were designed as a system for simultaneous delivery of iron and calcium. The salts were synthesized via a co-precipitation method and characterized by TEM-EDX, XRD, and FT-IR. All mixed salts with 0.14 ≤ x ≤ 0.35 yielded homogenous amorphous particles. The iron dissolution from these mixed salts showed a fourfold increase at gastric pH compared to Fe(III) pyrophosphate. In the food-relevant pH range, the salts with x ≤ 0.15 showed up to an eight-fold decrease in iron solubility. Despite this, reactivity of the mixed salts in tea was similar to that of FePP. Our results indicate that these mixed salts are potential dual-fortificants with tunable iron content and solubility