Changes in ascorbic acid, polyphenol content and antioxidant activity in minimally processed cactus pear fruits

Cactus pear fruits (Opuntia ficus indica Mill, cv. 'Gialla') were manually peeled, then placed in plastic boxes sealed with a film with high permeability to gases, and kept at 4degreesC for 9 days. After 3, 6 and 9 days, chemical, physical, microbiological and sensorial parameters, total phenols, vitamin C and antioxidant capacity were determined. In-package gas concentrations were measured almost daily. Vitamin C and antioxidant capacity remained unchanged, while polyphenols decreased after 6 days in storage. Of the chemical parameters, only pH and acidity changed significantly, without however, adversely affecting sensorial properties. Microbiological growth was limited and fungal colonies were never visually detected