Effects of level of nitrogen fertilizer, processing conditions and period of storage of frozen broccoli and cauliflower on vitamin C retention

Directly after harvesting, broccoli contained 116.3-116.4 mg of vitamin C in 100 g of fresh matter, and cauliflower contained 60.5-64.7 mg. Increasing the amount of nitrogen fertilizer from 80 to 120 kg N ha(-1) decreased the content of vitamin C only in cauliflower (by 7%), at the same time raising the level of nitrates by 44% in broccoli and by 33% in cauliflower. During the course of processing, the greatest losses in vitamin C content occurred during blanching: in broccoli by 41-42% and in cauliflower by 28-32%. Freezing resulted in little change of the vitamin C content, which was reduced by 15-18% in broccoli and by 6-13% in cauliflower during freeze-storage. After 12 months of storage, the level of vitamin C was 54.9-57.4 mg per 100 g of frozen product in broccoli and 38.5-41.9 mg per 100 g in cauliflower, being slightly higher at a storage temperature of -30 degrees C than at -20 degrees C. Copyright (C) 1996 Elsevier Science Ltd