Browsing by Author "Sakhno, Yu."

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The Influence of the Degree of Moisture and Temperature of Starch Heat Treatment on the Viscosity of Paste Solutions
(Ukrainian State University of Science and Technologies, 2025) Nikolenko, Mykola V.; Sakhno, Yu.; Myrhorodska-Terentieva, V. D.; Myrhorodska, K. D.; Terentiev, Vyacheslav V.
ENG: The possibilities of heat treatment of starch have not yet been fully utilized. The fact is that thermal treatment of starches can produce not only «split» starches, but also «cross-linked» starches, in which polycarbohydrate molecules are additionally bound by ether bonds. The latter can be formed by condensation of polycarbohydrate hydroxyl groups during starch heating without the use of additional chemical reagents. It has been suggested that the content of hydrate water in dry starch is an important factor because it can correlate with the number of intermolecular essential links of polycarbohydrate chains. Therefore, the purpose of the research is to determine the dependence of the viscosity of the paste solutions on the degree of initial humidity and the temperature of the heat treatment of starch. Studies have shown that there is a linear correlation between the kinematic viscosity of starch solutions and the hydrated water content in starch. The dependence of the viscosity of native starch paste solutions on the heat treatment temperature has the form of a convex curve, whereas for vacuum starch this dependence has the form of a rapidly declining exponential curve. It has been shown for the first time that preliminary vacuum dehydration of starch allows for a significant reduction in the temperature and time of starch dextrinization. FTIR studies of dehydrated starch spectra show a decrease in the number of intermolecular hydrogen bonds, which may be the main reason for the acceleration of their thermal degradation compared to starches with a higher degree of moisture.
Searching for the Chemical Component of the Starch Dehydration Process
(Ukrainian State University of Science and Technologies, 2026) Nikolenko, Mykola V.; Sakhno, Yu.; Myrhorodska-Terentieva, V. D.; Hrechka, Dmytro S.; Vashkevich, Olena Yu.
ENG: As is well known, the first stage of starch heat treatment is the dehydration process, which proceeds in a kinetic mode with a relatively high activation energy value of 40–60 kJ/mol. The reason for this may be both the energy-consuming process of hydrogen bond destruction in starch and the chemical reaction between the OH groups of polycarbohydrates with the formation of ester bonds. The aim of the study was to find evidence of the formation of such bonds during the heat treatment of corn starch. The studies were performed by FTIR spectroscopy in the temperature range of 60–2550C at a heating rate of 40C/min. It was found that the number of OH groups of polycarbohydrates gradually decreases during starch heating, while the water content and ether-bond signals, on the contrary, increase. An increase in water concentration was observed when starch was heated to a temperature of 1300C. It was concluded that these trends are well explained by the course of the condensation reaction between the OH groups of amylose and amylopectin molecules. For the first time, it was found that during prolonged drying of starch in a vacuum, even at a temperature of 500C, the crosslinking of polycarbohydrate molecules occurs due to the formation of ester bonds. It is noteworthy that such crosslinking occurs without the use of chemical reagents, but only by shifting the equilibrium of the condensation reaction as a result of the continuous removal of water from starch.