UV-A light treatment for controlling enzymatic browning of fresh-cut fruits

Enzymatic browning is critical in the preservation of the quality and the shelf-life of fresh-cut fruits. Non-thermal technologies such as UV radiation are emerging for controlling polyphenol oxidase (PPO) activity, the main agent responsible for browning. After determining the best operational conditions of a UV LED illuminator (2.43·10-3 Wm-2 irradiance), the anti-browning effect of UV-A light (390 nm) treatment at 25 °C over increasing time periods up to 60 min was assessed on fresh-cut apples (Golden Delicious, Granny Smith, Fuji) and pears (Abate Fétel, Decana). Colour variation (ΔE) and its percent reduction (%RΔE) were measured using a colorimeter and the greatest effect was observed in apples which showed higher %RΔE values than pears (58% vs 25% after 60 min exposure, respectively). Moreover electrophoretic and zymographic techniques demonstrated the inhibitory effect of UV-A irradiation on PPO activity. Anti-browning was found to be related to irradiance, exposure time and the fruit cultivar. Overall this study confirmed UV-A LED technology as an eco-friendly alternative to traditional approaches for reducing browning of minimally processed products. Industrial relevance: Treatment of fresh-cut products with UV-A LED is not only easy and inexpensive to produce but also presents few hazards for humans. Moreover, the use of LED light sources brings many advantages such as energy savings, device durability, low environmental impact, high luminous efficiency and little thermal effect. UV-A LED technology has great potential to meet the demands of the food industry in the processing of fresh-cut fruits and vegetables. In addition it could also be considered a pre-treatment of fruits and vegetables being processed for the production of snacks.