|MadSci Network: Chemistry|
Lemon juice loses about 50% of its vitamin C during heat treatment, while broccoli loses about 25% of its vitamin C during heat treatment. There are several factors that help explain this. The biggest factor is surface area. The vitamin C in lemon juice is in the solution and more exposed to the heat than the vitamin C in the broccoli, which is still in the cells of the broccoli and not exposed to the same intensity of heat for the same period of time. Other factors include the severity of the heat treatment and the type of container used. In general, the more severe the heat treatment, the more vitamin C that is lost. References: USDA Food Composition Tables (www.usda.gov) Karmas and Harris, Nutritional Evaluation of Food Processing, 3rd edition., 1988
Try the links in the MadSci Library for more information on Chemistry.