Inhibition of enzymatic browning by natural leafy vegetable extracts and keeping quality of fresh and dried apple rings

Fresh Red Delicious apple slices were dipped in natural leafy vegetable extracts (LVE) from cabbage, celery, mallow and fenugreek, and blanched in steam for 7 min. The effects of this treatment and of drying on chemical composition, colour, pigments (anthocyanins, carotenoids and chlorophylls), ascorbic acid content, and sensory properties of apple rings were investigated. Cabbage, celery and fenugreek were effective browning inhibitors in both fresh (LVE-dipped) and dried apples (LVE-dried). Results indicated that the treatment with cabbage, celery and fenugreek extracts inhibited the polyphenoloxidase activity after LVE-dipping to 97.35, 97.46 and 98.32%, respectively. Dried LVE-treated apple rings had the highest values for: rehydration ratio, coefficient of rehydration, drying ratio and the moisture content of rehydrated sample compared with steam-blanched and untreated samples. Results of the sensory evaluation indicated that apple rings dried after treatment with cabbage and celery extracts were the best products relative to others. Ochratoxin A and aflatoxins (B 1 , B 2 , G 1 and G 2 ) were not found in all dried samples investigated.