Physicochemical and Bioactive Characterisation of Edible and Waste Parts of "Piel de Sapo" Melon

Several scientific studies point fruits as rich sources of antioxidants but mainly focus on their edible part. However, fruits wastes are abundant sources of bioactive compounds and nutrients, which are considered to be health beneficial. The main purpose was to characterise juice, pulp, peel and seeds of Piel de Sapo melon, in terms of several physicochemical characteristics (soluble solids content, titratable acidity, pH, potassium, colour and water activity), some bioactive compounds (total phenolics, vitamin C, chlorophylls and total carotenoids) and total antioxidant activity. Juice, pulp, peel and seeds represent 47, 19, 27 and 5% of melon total weight, respectively. Peel and seeds stood out by their higher concentration of total phenolics compounds and antioxidant activity when compared to edible parts. The highest potassium concentration was found in seeds. Chlorophylls were only detected in peel, while carotenoids were not detected in any part of the melon analysed. Juice and pulp contributed to 69% of vitamin C amount of the whole fruit. However, its concentration in peel was equivalent to the ones observed in juice and pulp. These results pointed out the importance of fruit wastes valorisation and the development of strategies for their re-utilisation.