Lehnard A
Z Lebensm Unters Forsch. 1979 Aug;169(2):82-7. doi: 10.1007/BF01359512.
Spectrophotometric determinations of vitamin C were carried out on different kinds of vegetable products in raw state, after steam-cooking and freezedrying. Indicators used were in part 2,6-dichlorophenol-indophenol (DIP) and in part N-bromosuccinimide (NBS) and starch iodide, which at the same time allows a determination of other reducing interfering substances. The amount of L-dehydroascorbic acid (DAS), which together with L-ascorbic acid (AS) becomes vitamin C or total-vitamin C (VC), proved to be of special interest. During homogenisation of the vegetable samples in oxalic oxid solution AS was not oxidized. Other precautions like cooling or on oxygen-free atmosphere were not required. DAS was not found in raw vegetable products or after cooking. A high proportion of interfering substances especially when estimating VC was considered the cause for the normally measured amount of DAS. In freeze-dried samples of vegetable products a small amount DAS could be identified depending on the freezing process.
对不同种类的生鲜蔬菜产品、蒸煮后的蔬菜产品以及冷冻干燥后的蔬菜产品进行了维生素C的分光光度测定。所使用的指示剂部分为2,6 - 二氯酚靛酚（DIP），部分为N - 溴代琥珀酰亚胺（NBS）和淀粉碘化物，同时这也能测定其他还原性干扰物质。L - 脱氢抗坏血酸（DAS）的含量特别令人关注，它与L - 抗坏血酸（AS）共同构成维生素C或总维生素C（VC）。在蔬菜样品于草酸氧化溶液中匀浆的过程中，AS未被氧化。无需采取其他诸如冷却或在无氧氛围下等预防措施。生鲜蔬菜产品或烹饪后的蔬菜产品中未发现DAS。在估算VC时，大量干扰物质被认为是通常测得的DAS含量的原因。在蔬菜产品的冷冻干燥样品中，根据冷冻过程的不同，可鉴定出少量DAS。
