The fresh-cut industry is constantly growing and generating wastes. The major challenge for this industry consists in an environmentally sustainable production through re-utilization of by-products, for instance, in extraction of bioactive compounds. In this paper, the nutritional and functional compounds of apple, potato, cucumber, melon and watermelon by-products were investigated. The amount of by-product produced was of 10.10 to 30.80% of initial fresh weight depending on the product. By-products were characterized by low protein (<20 g/kg fresh weight) and fatty acid content (<5 g/kg fresh weight) and high levels of minerals. Carbohydrates content ranged from 43.7 to 235 g/kg fresh weight, while total dietary fibre was between 20 and 150 g/kg fresh weight The content of antioxidants (53.6 to 3453.2 mg/kg fresh weight) and total polyphenols (124.5 to 4250.2 mg/kg fresh weight) depended strongly on the type of by-product. In most cases, the nutritional and bioactive content was higher in the peel than in whole product. Apple peel was rich in carbohydrates, total dietary fibre, antioxidants and total polyphenols. Potato peel was high in iron. Melon was rich in magnesium. Watermelon peel was characterized by the level of potassium, and cucumber peel was rich in manganese, zinc, phosphorous, calcium and sodium. All these data demonstrate than natural by-product from fresh-cut industry could potentially be utilized as ingredients to design new functional foods with a future market.
Keywords: Peel; fibre; minerals; protein; skin.