Effects of different edible coatings on polyphenol oxidase activity and colour of fresh-cut apple during cold storage

Fresh-cut fruits are highly susceptible to enzymatic browning. The aim of this study was to evaluate the effects of different coatings on polyphenol oxidase (PPO) activity and colour of ‘Royal Gala’ apple cubes during storage at 4°C. The main constituents (polysaccharides) of the coatings used were carrageenan, alginate, the exopolysaccharide (EPS) from the marine microalga Porphyridium cruentum, pectin, and carboxymethyl cellulose (CMC). When PPO activity increased, the apple cubes became browner (L* values decreased, and/or a* and/or b* values increased) for pectin, carrageenan, EPS 5 g.L–1 and CMC coatings. EPS coated apple cubes, in particular, did not present the best results in order to prevent the colour changes and to lower down PPO activity, but the results obtained were very similar to those of alginate. The coating based on pectin was the most recommended to preserve fresh-cut ‘Royal Gala’ apple closely followed by CMC.