Recent advances in controlling polyphenol oxidase activity of fruit and vegetable products

Enzymatic browning is associated to the colour alteration and phenolic degradation of minimally-processed fruits and vegetables. The main responsible is polyphenol oxidase (PPO, EC 1.14.18.1), a copper-containing oxidoreductase which catalyzes two different enzymatic reactions involving oxygen and polyphenolic substrates which are polymerized to dark pigments. Since the control of PPO activity is until now an open question in the agro-food industry, the search for new anti-browning strategies is moving towards replacing conventional treatments. The present review is aimed to discuss non-thermal technologies and natural inhibitors considering their anti-PPO impact in relation to enzyme source, processing conditions, type and concentration of bioactive compounds. These innovative treatments can be proposed as eco-friendly systems for effectively reducing PPO activity thus preventing enzymatic browning and consequently improving sensory, antioxidant and nutritional properties of fruit and vegetable products.