Role of protease and oxidase activities involved in some technological aspects of the globe artichoke processing and storage

The present review has summarized the main aspects related to the role of the principal endogenous enzymatic activities (proteases and oxidases) involved during processing and storage of the globe artichoke, one of the most important vegetable crops in the Mediterranean Basin, whose edible inflorescences (commonly called 'heads') have now gained a reputation as "functional food". Consequently, an increasing positive trend of their commercialization is recorded both as traditional fresh or appertized preserve, minimally processed vegetables (MPV), food ingredient in prebiotic foods, or as a clotting agent to produce cheese. Literature confirmed the positive contribution in cheese-making of the globe artichoke extracts as a source of alternative proteases (Cardosin A) to calf or microbial rennet. These extracts are obtained from the flowers (flosculi), in the vacuoles of stigmatic papilla and in the epidermal cells of the stylum. It has been pointed out that the better results were obtained using goat's milk and extracts of globe artichoke from the cultivars 'Camus de Bretagne' and 'Violetto di Sicilia', although waste biomass of globe artichokes or from cardoons could also be validly destined as clotting agent. On the other hand, in the globe artichoke processing as MPV and their relative storage, polyphenol oxidase (PPO, EC 1.14.18.1) and peroxidase (POD, EC 1.11.1.7) are the main responsible for tissue injuries and loss of their nutritional value, due to the oxidation of the phenolic compounds and subsequently polymerization with some nitrogen compounds. Finally, this paper briefly describes the possible strategies to achieve an efficient control of browning, starting from the agronomical choices in the pre-harvest stage, to the reliable guidances of the combined use of efficient inhibitors against degenerative activities during the post-harvest stage, since it would be very difficult that a single treatment could extend the shelf life of the MPV globe artichoke.