[Evaluation of the nanosize and stability of aqueous dispersions of iodinecontaining conjugates based on carriers of plant origin, promising for iodine enrichment of foods].

The high proportion of iodine deficiency diseases in the structure of general morbidity determines the relevance of creating new nontoxic iodine-containing compounds and improving the processes of iodization of foods of mass consumption. In recent years, to solve this problem, a number of iodine-containing compounds based on natural polymers have been proposed, including pectin (iodinepectin), casein (iodine-casein), inulin (iodine-inulin). It seems promising to create iodine-containing conjugates for food industry not only based on natural polymers, which are not individual compounds, but also based on low-molecular plant metabolites that have a high potential for correcting public health. The attention of researchers is attracted, in particular, by the glycosides of Stevia rebaudiana, which have positively proven themselves in the food industry for many years. Current trends in the development of industrial production of iodine-fortified products also include requirements for the compatibility of iodine-containing concentrates with food industry technologies, especially in the formation of time-stable micro-heterogeneous aqueous dispersions. In connection with the above, the purpose of the research was to confirm the formation of an iodine conjugate with a low molecular weight metabolite of Stevia rebaudiana (glycoside rebaudioside A) by infrared (IR) spectroscopy; and to assess the resistance to sedimentation of its aqueous micro-heterogeneous dispersions (iodine-glycoside) comparatively with iodine compounds with natural plant polymeric carriers - pectin (iodine-pectin) and inulin (iodine-inulin) by the method of nanostructural analysis. Material and methods . The IR spectra of the compounds were recorded on a Fourier spectrometer. Measurement of particle sizes in dispersions of iodine-containing substances was carried out on a laser analyzer, wave length 375 nm, in a quartz cuvette (7 ml) after 0, 2, 4, 6, 10, 24, 72 and 144 h. To prepare dispersions, a weighed portion of iodine-pectin (105 mg) was mixed in 100 cm3 of water (600 rpm) at a temperature of 35-40 °C for 60-70 min, weighed portions of iodine-glycoside (120 mg) and iodine-inulin (49.7 mg) were dissolved in 100 cm3 of water at room temperature (23 °C) for 3-4 min. Results . An IR spectroscopy study of the interaction of iodine with rebaudioside A indicated the stabilization of molecular iodine by the functional groups of the glycoside, leading to the formation of a stable iodine-glycoside conjugate. Assessment of the aqueous dispersions of particles of this conjugate by nanostructural analysis showed that the substance iodine-glycoside formed a stable microheterogeneous dispersion with a particle diameter of about 300 nm, which didn't undergo sedimentation during the entire observation period (6 days). Aqueous dispersions of the iodine-inulin with a particle size of 10 nm were comparable with true solutions and remained also stable throughout the entire observation period. Particles of the iodine-containing compound iodine-pectin formed moderately stable aquatic dispersed systems, the time of complete sedimentation of which was 6-10 h. Conclusion . The study of the IR spectra of rebaudioside A and the synthesized sample iodine-glycoside made it possible to confirm the conclusion about the inclusion of iodine molecules in the structure of glycoside molecules. Micro-heterogeneous stable dispersions of this conjugate, as well as iodine-inulin substances, can be convenient concentrates for enriching milk with iodine. Rapid aggregation of particles of iodine-pectin substances in concentrates can prevent their uniform distribution in the target environment, which reduces the effectiveness of industrial technologies for iodine-fortified foods for the mass prevention of endemic goiter.