IMPORT-SUBSTITUTING FOOD ADDITIVE E316 (SODIUM ISOASCORBATE): PRODUCTION PATTERNS

Sodium isoascorbate is one of the most popular antioxidants in food industry. Russia imports it from abroad. Thus, import substitution requires a thorough research into the patterns of isoascorbate technology production and development. The mass fraction of the main substance in the solution and crystals of the target product was determined by iodometric titration. It was established that the rate of oxidative degradation of sodium isoascorbate solutions is from 0.01%/h at 25°C to 0.80%/h at 82°C, depending on the temperature and duration of the process, as well as contact with metal and oxygen of the air. The experiment substantiated the choice of metal equipment and the temperature limit of 60°C. The equivalent pH values during the interaction of isoascorbic acid solutions with sodium hydroxide, carbonate, and sodium bicarbonate solutions were 7.5, 7.0, and 5.6, respectively. The author also defined the influence of equilibrium concentrations of aqueous solutions of isoascorbic acid and sodium isoascorbate on temperature. The optimal method was to add a solution of sodium hydroxide into a solution of isoascorbic acid with a ratio between the masses of sodium hydroxide solution, crystalline isoascorbic acid, and prepared water, respectively, 1:2.11:6.13. The solution obtained at such ratios had a supersaturation coefficient of 1.05 at a temperature of 60°C. The experiment revealed the time required to establish equilibrium in the crystallizing system and the dependence of the solubility of sodium isoasorbate on the mass fraction of ethyl alcohol in solution. It was proposed to separate the target product from the solution by isohydric crystallization followed by isothermal crystallization, followed by washing the crystals with ethyl alcohol. According to the proposed technology, sodium isoascorbate was obtained with a mass fraction of the basic substance of at least 99.0%. The obtained data can be used in the development of industrial technology for the production of sodium isoascorbate.