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Vol. 18 (2015 year), No. 1
Kuchina Yu. A., Dolgopyatova N. V., Novikov V. Yu., Konovalova I. N., Prinsteva M. Yu., Sagaidachny V. A.
Thermal decomposition of natural polysaccharides:
Chitin and chitosan
The results of the thermal analysis of shrimp’s chitin and chitosan have been presented (samples of polysaccharide differed by the deacetylation degree have been studied). The thermal analysis has been carried out by differential thermogravimetry and differential scanning calorimetry. Activation energy of process of chitin and chitosan thermal destruction has been calculated
(in Russian, стр.6, fig. 5, tables. 1, ref 6, Adobe PDF, Adobe PDF 0 Kb)
Vol. 18 (2015 year), No. 1
Novikov V. Yu., Derkach S. R., Shironina A. Yu., Mukhin V. A.
Kinetics of the enzymatic hydrolysis of hydrobiont tissue proteins:
Effect of the enzyme introduction
Kinetic laws of enzyme hydrolyze for Atlantic cod tissues have been studied. Enzyme specimen produced from hepatopancreas of Kamchatka crab Paralithodes camtschatica was used for carrying out hydrolyzes (proteolysis). A new method of protein hydrolyzate production based on multiple enzyme injection (over equal time intervals) into a reactive system has been worked out. It has been shown that this method assures increase of maximum degree of hydrolyze. A kinetic model describing the mechanism for enzyme hydrolysis of fish protein in the proposed technology has been developed. The model is based on the existence of easily and hardly hydrolyzed protein fractions. In the frame of the obtained kinetic model, the second-order constants of intermediate stage rates of proteolysis have been calculated. The content of free amino acids increases 2-fold, and dispersity of aqueous dispersions increases for the hydrolysates obtained in the multiple injection process in comparison with hydrolysate obtained in a traditional single-stage process.
(in Russian, стр.10, fig. 5, tables. 5, ref 13, Adobe PDF, Adobe PDF 0 Kb)
Vol. 19 (2016 year), No. 3, DOI: 10.21443/1560-9278-2016-3
Novikov V. Yu., Dolgopyatova N. V., Konovalova I. N., Kuchina Yu. A.
Properties of aqueous dispersion of chitosan and chondroitin sulfate complex derived from aquatic organisms
Investigation of production of chondroitin sulfate, chitosan and polyelectrolyte complexes based on them received from the local marine raw materials is relevant from the point of view of developing a comprehensive waste-free technology for natural raw materials processing. The objects of study are chitosan derived from the shell of the Kamchatka crab Paralithodes camtschaticus and chondroitin sulfate derived from cartilage of salmon Salmon salar. To determine the surface tension of polyelectrolyte complex solutions and dispersions the Wilhelmy method has been used, the effective radius of particle dispersion has been calculated by light scattering, measurements of effective viscosity have been carried out under shear deformation. The conditions of formation, surface and rheological properties of the chitosan and chondroitin sulfate complex extracted from aquatic organisms in the Barents Sea have been studied. Obtaining conditions and molar ratios of these polyelectrolytes in which the aqueous dispersion of the complex remains stable for a long time have been established. It has been found that by addition of chondroitin sulfate solution to chitosan solution in molar ratios of 1 : 3; 1 : 6 the dispersion of the polyelectrolyte complex stable for 2 to 3 days has been formed. The polyelectrolyte complex dispersions behave as non-Newtonian pseudoplastic liquid. When the molar ratio of the mixed solution is 1 : 1 (regardless of the sequence of mixing) suspension of the polyelectrolyte complex has been formed, then there is precipitation. Equilibrium surface tension of the aqueous dispersion of the polyelectrolyte complex is higher than that of solutions of chondroitin sulfate and chitosan. The effective radius of particles in the complex dispersion has been determined. The effective radius of the particles in the complex dispersion depends on the molar ratio of chondroitin sulfate : chitosan. A qualitative scheme of formation of polyelectrolyte complex from chitosan and chondroitin sulfate as an insoluble precipitate and as a form of stable aqueous dispersion has been proposed. Aqueous dispersions based on chitosan and chondroitin sulfate complex can be used to stabilize suspensions, emulsions, to create foods with a therapeutic and prophylactic properties
(in Russian, стр.8, fig. 4, tables. 1, ref 13, Adobe PDF, Adobe PDF 0 Kb)
Vol. 20 (2017 year), No. 1, DOI: 10.21443/1560-9278-2017-20-1/1
Derkach S. R., Berestova G. I., Novikov V. Yu.,Kolotova D. S., Brichka K. M., Simonsen G
Chemical composition of Pechora Sea crude oil
The physicochemical properties of the Pechora Sea shelf oil and its chemical composition have been studied using the methods of refractometry, titrimetry, viscometry, rheometry and standard methods for the analysis of oil and petroleum products. The fractionation of oil is held at atmospheric pressure, some fractions boiling at the temperature below and above 211 °C have been received. Chemical structural-group composition of oil and its components has been investigated using a Fourier infrared (IR) spectroscopy method. The density of oil has been obtained, it is equal to 24.2 API. The chemical composition analysis shows that water content in the investigated oil sample is about 0.03 % (by weight). The oil sample contains hydrocarbons (including alkanes, naphthenes, arenes) and asphaltenes with resins; their content is equal to 89 and 10 % (by weight) respectively. Alkane content is about 66 %, including alkanes of normal structure – about 37 %. The solidification temperature of oil sample is equal to –43 °C. This low temperature testifies obliquely low content of solid alkanes (paraffin). Bearing in mind the content of asphaltenes with resins we can refer the investigated oil sample to resinous oils. On the other hand spectral coefficient values (aromaticity quotient and aliphaticity quotient) show that oil sample belongs to naphthenic oils. According to the data of Fourier IR spectroscopy contents of naphthenes and arenes are 5.9 and 17.8 % respectively. Thus, the obtained data of chemical structural-group composition of crude oil and its fractions indicate that this oil belongs to the heavy resinous naphthenic oils. The rheological parameters obtained at the shear deformation conditions characterize the crude oil as a visco-plastic medium.
(in Russian, стр.10, fig. 3, tables. 5, ref 14, Adobe PDF, Adobe PDF 0 Kb)
Vol. 20 (2017 year), No. 3, DOI: 10.21443/1560-9278-2017-20-3
Novikov V. Yu., Konovalova I. N., Kuchina Yu. A., Dolgopyatova N. V., Cherkun Yu. A.
Hydration mechanism of heterogeneous alkaline deacetylation of chitin
In the work the hypothesis has been proposed explaining the features of the kinetics of chitin/chitosan alkali deacetylation reaction in highly concentrated solutions of sodium hydroxide, which almost completely stops after 30–60 min after the start of the reaction and does not provide a fully deacetylated product – chitosan. Analysis of the known publications explaining the observed decline in the deacetylation reaction rate has been executed, and some new experimental results confirming the authors' conclusions have been presented. It has been shown that water present in the reaction mixture renders the greatest influence on the kinetics of chitin deacetylation, and can lead to hydration as chitin molecules and ions alkalis as well. The hypothesis has been offered according to which in the reaction mixture there is the dynamic balance between hydrated alkali ions, molecules of chitin and formed acetate ion, which can shift depending on the concentration of the reacting particles. It has been suggested that in concentrated alkali solutions water is present almost entirely or partly in the form of hydrate shells of alkali ions, and to a lesser extent in the form of "free" water. Apparently, the limiting stage of the deacetylation reaction is the hydration of chitin macromolecules by water molecules, which are released during nucleophile replacing hydroxyl ions by acetyl radicals binding with chitin amino groups. Acetate ion is a product of the deacetylation reaction. Acetate ion hydration energy is less than hydration energy of hydroxyl ion, so the acetate ion is less hydrated, as a result some water is released. In these conditions, hydration of chitin macromolecules occurs in the local area around the chitin molecules, where the high water concentration is created after deacetylation. The alkali concentration in all reaction volume remains practically constant
(in English, стр.10, fig. 5, tables. 1, ref 31, Adobe PDF, Adobe PDF 0 Kb)
Vol. 24 (2021 year), No. 4, DOI: 10.21443/1560-9278-2021-24-4
Novikov V. Yu., Rysakova K. S., Baryshnikov A. V.
Application of the linear method of discriminant analysis of reflectance spectra in the near infrared region for the species identification of fish of the Salmonidae family
It is well known that fish belonging to the Salmonidae family differ in their nutritional value. Anatomical and morphological features of different salmon species have a certain similarity; therefore, representatives of this family are most often falsified. Assortment falsification of products from fish of this family is usually carried out by replacing more valuable species with cheaper ones with a reduced nutritional value. Most often, counterfeiting of Atlantic salmon (salmon) by Far Eastern ones (chum salmon, pink salmon, chinook salmon, coho salmon) is found. Near infrared spectroscopy (NIR) is now increasingly used for identification and authentication of closely related organisms, in some cases being a rapid method replacing genetic analysis. We have obtained diffusion reflectance spectra of NIR radiation for three species of fish from the Northern Basin belonging to the salmon family. The best classification by fish species has been obtained by analyzing the NIR spectra of pre-dried fat-free muscle tissue samples. In case of wet samples, the observed differences are less significant, up to insignificant differences in individual values from neighboring clusters. The possibility of using the method of linear discriminant analysis of the NIR reflection spectra of muscle proteins for the species identification of fish has been shown.
(in Russian, стр.10, fig. 5, tables. 2, ref 22, AdobePDF, AdobePDF 0 Kb)