Effects of processing on anthocyanins,carotenoids and vitamin C in summer fruits and vegetables

The purpose of this study was to evaluate the effects of processing, i.e. heating (98 °C, 10 min), freezing (−20 °C) and freeze-drying on anthocyanins, carotenoids, and vitamin C in summer fruits and vegetables, i.e. cherries, nectarines, apricots, peaches, plums, carrots and red bell peppers. The commodities were collected from growers located in the Otago region (namely Cromwell, Roxburgh, Mosgiel and Clinton), New Zealand. The results revealed that each commodity contained different contents of phytochemicals. The content and the process stability of phytochemicals in each commodity were influenced by the geographical location of the growers. In general, a high content of phytochemicals was found in summer fruits and vegetables grown in Otago compared to those grown in the Northern Hemisphere, e.g. anthocyanins in cherries, nectarines, peaches and plums; total carotenoids in red bell peppers and nectarines and vitamin C in cherries, peaches, red bell peppers and carrots. Heating and freezing enhanced the release of membrane bound anthocyanins, resulting in higher content after processing compared to fresh commodities. In the commodities studied, with the exception of red bell peppers, the stability of ascorbic acid was increased if ascorbic acid oxidase was inactivated for example by heating.