Effect of time, temperature and storage condition on the some of phyto-chemical and physicochemical traits of watercress (Nasturtium officinale L.) medicinal plant

The present study was aimed to study the effects of storing temperature (0 and 5°C) and packaging type (cellophane and plastic containers with air-gated) on storage life of watercress (Nasturtium officinal L.) leaves during 14 days storing. Changes in ascorbic acid, total phenolics, flavonoids and sugar content as well as antioxidant capacity were traced in this experiment. Storing resulted in a significant decrease in flavonoid content of watercress leaves and its level decreased from 46.4mg/g of dry weight to 36.2mg/g. Similarly, during 7 and 14 days storing, the ascorbic acid content of leaves significantly decreased from 68.1mg/100g of fresh weight to 63.5 and 55.1mg/100g of fresh weight, respectively. In the case of antioxidant capacity, the effects of storing time and packaging type were significant (p<0.01). During storage, total phenolics were significantly increased from 11.6 mg/g of fresh weight to 13.6 mg/g of fresh weight. In contrast, the effects of storing temperature and type of packaging on phenolic compounds were not significant. The leaves stored in air-gated containers had the higher water content and, in consequence, the better quality than that of those stored in cellophane containers. It can be concluded that the leaves stored in aerated containers and 0°C had the better quality due to the lower respiration.