差热分析法对食盐加碘剂碘酸钾的稳定性研究

Stability of the salt iodization agent potassium iodate： a differential thermal analysis

目的考察碘酸钾固体的热稳定性及其在氯化钠、维生素E、维生素C和亚铁氰化钾中的热稳定性。方法利用HER-2型差热仪对碘酸钾及其在氯化钠、维生素E、维生素C和亚铁氰化钾中的稳定性进行差热研究，得到差热曲线并进行分析。结果碘酸钾固体的分解温度为525℃；碘酸钾氯化钠混合时在300℃以下稳定；维生素C在170～200℃时不稳定，发生化学变化；碘酸钾和维生素C混合在145-160℃时会发生氧化还原反应；碘酸钾与维生素E混合，在300℃内稳定；亚铁氰化钾在300℃内稳定；加碘食盐在烹饪过程中，在温度范围内（300℃内）稳定。结论碘酸钾在525℃以下具有良好的稳定性，碘酸钾碘盐在烹饪过程中易与蔬菜中的维生素C发生反应而造成碘损失，所以在烹饪时应该在饭菜出锅前加入食用碘盐。

Objective To investigate the thermal stability of solid potassium iodate and potassium iodate as additive in the sodium chloride, vitamin E, Vitamin C and yellow prussiate. Methods HCR-2 type Differential Thermal Analyzer was used to carried out the differential thermal analysis of the potassium iodate and the potassium iodate in the sodium chloride, vitamin E, vitamin C and the yellow prussiate, and differential thermal curves were obtained and analyzed. Results The decomposition temperature of solid potassium iodate was 525 ℃ ; when mixed with sOdium chloride, potassium iodate was stable below 300 ℃; vitamin C was unstable at 170 - 200 ℃ and underwent chemical changes; iodate and vitamin C underwent oxidation-reduction reaction at 145 to 160 ＊C; potassium iodate with vitamin E at 300 ＊C was stable; yellow prussiate at 300 ~C was stable; iodized salt was stable at cooking temperature below 300 ℃. Conclusions The potassium iodate has good stability below 525 ℃, however, potassium iodate iodized salt in the cooking process is easy to react with vitamin C in vegetables causing iodine losses, so iodized salt should be added just before the dish is done.