Influence of Preparing Method on Antioxidant Activity and Polyphenols Content of Green Walnuts Comfiture

The present study reports on the proportion of endocarp, mesocarp and exocarp in green walnuts and on the total phenolic content and antioxidant activity of these fractions and of whole green walnuts (Juglans regia L.). The total phenolic content was determined by the Folin– Ciocalteu method and the antioxidant activity was assessed by the ability to quench the stable free radical 2,2'-diphenyl-1-picrylhydrazyl (DPPH). The highest total phenolic content was recorded in endocarp, followed by exocarp and mesocarp, while the antioxidant activity of these fractions kept the same order. Traditionally the comfitures are made only from endocarp but this procedure removes mesocarp and exocarp which become wastes. In order to recover these valuable fractions, in this study, besides the comfiture made only from endocarp (V1), a comfiture from green walnuts without exocarp (V2) and another one from whole green walnuts were made and analysed in terms of sensorial properties, content of polyphenols and antioxidant activity. The comfiture made only from endocarp was superior to the other variants in terms of phenolics content and antioxidant activity. However the comfiture made from green walnuts without exocarp proved to be acceptable in terms of sensory features, had high phenolic content and antioxidant activity and allowed reducing waste from 48.84% to 16.52%.