探究酸度、温度、放置时间对维生素C稳定性的影响

Exploration of the influence of acidity,temperature and standing time on the stability of vitamin C

用直接碘量法测定维生素 C 在不同 PH 值，不同温度以及不同放置时间下维生素 C 含量的变化。结果表明在pH 值为2～5时，维生素 C 比较稳定；反之，无论是强酸性还是强碱性条件下，维生素 C 含量均随时间的延长而显著减少。维生素 C 的含量随温度升高也会显著减少。另外，在水溶液中，维生素 C 的含量随放置时间增长而显著减少，如在30℃时，其半衰期为52.9 h。该研究为人们日常的生活中合理地存储、食用维生素 C 提供一定的参考价值。

Direct iodimetry is used to detect the change of the vitamin C in different PH, temperatures and standing times. The results show that vitamin C is relatively stable in pH 2 ～ 5; on the other hand, whether in strong acid or alkaline conditions, vi-tamin C content significantly decreases with the extension of standing time. The content of vitamin C will significantly reduce with the increase of temperature. In addition, in water solution, the vitamin C content decreases significantly with the extension of stand-ing time, such as at 30 ℃ , with a half-life of 52. 9 h. The research has certain reference value for people＇s daily life in reasonable storing and taking vitamin C.