摘要
通过测定变化前后的维生素C的紫外吸收光谱,发现利用其差别的程度,即用330nm处的OD值(opticaldensity)可判断有效维生素C的变化情况。模拟食品加工中的一些条件,运用此法及I2定量法考察了有效维生素C的稳定性。结果观察到:碱性下有效维生素C通过形成新的物质而被破坏;虽然溶液中还原态维生素C在自然状态下不断损失,且第10d后损失速度加快,但20d内有效维生素C保存还较多;中性盐对有效维生素C有保护作用,而氨基酸与维生素C作用产生色变,加速维生素C的破坏;冻藏能保护维生素C,加热则破坏维生素C;由氧化剂I2介导氧化形成的氧化态维生素C极不稳定。
The ultraviolet absorptions of vitamin C and its changeable products were studied, it was found that the change of effective vitamin C can be determined by the optical density at 330 nm (OD330), In some imitative conditions of food processing, the stability of effective vitamin C was tested. Vitamin C was destroyed by forming a new unstable compound in basic condition. The level of reduced vitamin C dissolved in water decreased with the days going and declined more rapidly after 10 days , but the greater part of vitamin C was still effective in 20 days. The cold storage and neutral salt might play a role in protecting vitamin C. The heating and amino acids accelerated the change of vitamin C. Oxidized vitamin C formed by the oxidation of I2, was very unstable.
关键词
维生素C
定量法
稳定性
研究
effective vitamin C
ultraviolet absorption
iodometry
stability