【摘要】 维生素C是人类必需的重要水溶性抗氧化营养素之一,然而它也是一种热敏性的化合物,与许多其他热敏性营养素相似,在高温条件下容易造成热破坏,这令在传统的加热蒸发浓缩生产果蔬汁过程中,往往会造成产品中天然有效营养成分的热损失。因而探究在冷冻浓缩条件下果汁蔬菜汁维生素C的变化,作为一般热敏性有效成分的表征,对在加工过程中保存有效成分具有很大意义。本研究利用碘量法测量维生素C,对比冷冻浓缩和蒸发浓缩前后维生素C的含量变化及损失率。结果显示,相比于传统蒸发加工生产工艺,冷冻浓缩技术不仅能减少维生素C的损失,而且由于水的冷冻潜热只有蒸发潜热的约七分之一,因而具有很大的节能降耗潜力。是符合现代社会发展的绿色生产工艺,所生产的浓缩果疏汁能有效保留其原有的营养及风味。更多还原

【Abstract】 Vitamin C(VC) is an important human essential water soluble antioxidant nutrients, but its heat sensitive nature leads to thermal damage under high temperature conditions, such as evaporating concentration. Therefore, it is necessary to investigate whether the production of fruit and vegetable juice can reduce the loss of VC in freezing concentration. The iodometric method is used in this experiment to determine the VC level changes of a simulated fruit juice. The VC levels before and after freeze concentration and evaporating concentration are compared. The experimental data of this study shows that the average loss of VC during freeze concentration was around 1 %, nevertheless the traditional evaporation process was 3 %~18 %. Considering the freezing latent heat of water is only one-seventh of its evaporation latent heat, indicating that as novel processing technology, freeze concentration is a green production process, and promising in producing high quality concentrated fruit or vegetable juice to meet the modern life requirement.更多还原