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Vol. 20 (2017 year), No. 3, DOI: 10.21443/1560-9278-2017-20-3

Cherepanov I. S., Sergeeva K. A.
Melanoidin formation in ethanolic monosaccharide – arylamine – copper (II) systems

Results of studying of melanoidin formation regularities at interaction of D-glucose and D-xylose with p-amino benzoic acid (PABA) in acidic ethanolic media have been presented; features of the chosen threefold systems are, firstly, existence of the low-active amino-compound of benzene series, secondly, presence of catalytic amounts of the biogenic metal. Regularities of melanoidins structure formation from similar systems are almost not studied, at the same time some important biological properties are predicted for them that demands research of reactions' kinetics and development of techniques of their directional synthesis. Studying has been carried out by synthetic methods in total with a sample drawing technique with UV-Vis-spectrophotometry filing and engaging of FTIR-spectroscopy. Based on electronic spectra analysis more intensive melanoidin formation in case of reaction from D-xylose has been shown, this can be bound to steric hindrance and to ability of aldopentoses to give more reactionary capable intermediates in comparison with aldohexoses. The accelerating role of copper (II) ions as the complexing center catalyzing both formation and degradation of the intermediate products at different reaction stages has been confirmed, at the same time the accelerating action is considerably shown since copper ion concentrations about 60 mg/l, but Cu(II) chelation degree by final products is low. The effect of solvent has been noted, in particular the influence of ethanol on nature of amino-carbonyl interactions manifested in strengthening of carbohydrates tendency to re-cyclization, it also probably accelerates melanoidin formation. The data obtained have shown the percent of carbohydrates direct destruction (caramelization) in the presented conditions is insignificant, that allows developing based on the present researches target synthetic techniques for melanoidin products' preparation.

(in English, стр.6, fig. 6, tables. 1, ref 6, Adobe PDF, Adobe PDF 0 Kb)

Vol. 25 (2022 year), No. 3, DOI: 10.21443/1560-9278-2022-25-3

Cherepanov I. S. , Mukhdarova E. Sh.
Study of D-glucose influence on L-ascorbic acid destruction in aqueous-ethanolic media

The study of ascorbic acid transformation processes in aqueous – ethanolic systems is an important area of research in food chemistry, and therefore recently there has been an increased interest in studying the possibility of stabilizing ascorbic acid in the form of O-derivatives by the biologically active substances. The paper examines the behavior of ascorbic acid – D-glucose double systems in aqueous-ethanolic media of various compositions (96 % EtOH, 40 % EtOH) under thermal degradation conditions compared to systems without carbohydrate additives. It has been shown that in 40 % ethanol, degradation processes develop faster compared to reactions in 96 % ethanol; in dual systems, regardless of solvent composition, ascorbic acid reacts faster than carbohydrate-free systems. Based on electronic and vibrational spectroscopy data, the joint participation of ascorbic acid and monosaccharide in thermodestruction reactions has been established, which is accompanied by the sequential formation of dehydroascorbic acid derivatives. These derivatives are L-gulono-?-lactones with different degrees of substitution, containing no endiol fragments of ascorbic acid, and as a result do not have antioxidant properties. As a result of the studies, the absence of ascorbic acid stabilization by D-glucose in the form of O-derivatives in the studied double systems is shown, which is probably due to the formation of thermodynamically stable of dehydroascorbic acid derivatives during the reactions, even in low-water systems. Further studies are planned in the direction of choosing the optimal conditions that allow isolating ascorbic acid derivatives (or molecular complexes) with reducing properties, which will make it possible to obtain products with antioxidant functionality.

(in Russian, стр.10, fig. 9, tables. 0, ref 20, AdobePDF, AdobePDF 0 Kb)