Starch is an important raw material for various industries, including food, chemical, pharmaceutical, textile, etc. Analysis of scientific and technical publications indicates the advantage of heat treatment among various methods of modification of starches. The advantage of the process is that by changing its conditions, it is possible to obtain dextrins with different functional properties, that is, to expand the range of modified starches on the market, adapting to the specific needs of users.
As a result of microscopic studies, it was shown that the average size of starch particles decreases after heat treatment. The decrease in particle size is explained by their dehydration and a change in the degree of packing of biopolymer macromolecules due to their destruction and repolymerization.
Research using thermal methods of analysis and FTIR-spectroscopy showed that the condensation of hydroxyl groups of polysaccharides occurs in a wide temperature range and is not manifested by separate endo-effects on DSC curves. For the first time, a linear correlation was established between the values of the activation energies of the processes of dehydration and dextrinization of potato and corn starches, which indicates the independence of such processes from the botanical origin of starches.
X-ray diffraction studies showed that in the process of heat treatment of starch, there is an increase in the intensity of reflexes in the region of 2=10-20, which indicates the reorientation of crystallites and an increase in the degree of order of polysaccharide macromolecules during heating.
It was found that the kinetic curves of amylose leaching from starch are best described by the Kruger-Ziegler equation, which describes heterogeneous chemical processes with a time-varying diffusion coefficient. The apparent activation energy of the hydrothermal amylose leaching process decreases with increasing temperature. It was concluded that the decrease in the activation energy is due to the transition of the process from the kinetic to the diffusion mode. It was proposed for the first time to consider amylose leaching as a heterogeneous pseudochemical process.
It was established that the activation energy of the amylose leaching process decreases with increasing acidity of paste solutions, which is due to the effect of hydrogen ions on the strength of hydrogen bonds. The mechanism of such influence was studied by the method of quantum-chemical modeling.
To analyze MMR of amylose pastes, thin-layer chromatography with scanning of chromatographic spots and determination of color coordinates in the CIELab system was used. Profiles of changes in the total color difference of chromatographic spots in the direction of movement of the eluent front made it possible to characterize changes in the molecular weight of amylose after starch dextrinization. For the first time, it was proposed to divide heat-treated starches into two separate groups - with an increased and with a reduced degree of amylose polymerization.
The study of the dynamic viscosity of the pastes showed that with increasing liquidity, the viscosity of the pastes initially increases, and then at a liquidity of 9-12 s-1 it begins to gradually decrease, which is explained by the transition of tonal flow regime to pseudoplastic flow.
For the first time, the dependence of the efficiency and mechanism of starch dextrinization on the degree of their hydration was established: the lower the initial water content in starch, the greater the degree of cross-linking of its polysaccharides during heat treatment. For the first time, the process of starch modification by incorporation of calcium orthophosphate nanoparticles was investigated. It was established that the incorporation of starch allows reducing the temperature and time of heating starches to achieve the required viscosity indicators of their paste solutions.
The technological scheme of the production site for obtaining incorporated dextrins, which is proposed to be implemented at starch production enterprises, was developed. It is proposed to use wet starch as raw material. It was established that the method of obtaining incorporated dextrin proposed by us is economically beneficial.
A test report was received from Korsa LLC, which confirms the effectiveness of the proposed method of synthesis of incorporated dextrin and its compliance with the requirements of DSTU 4380:2005.
