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

Abstract

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.

Bioactive, technological-functional potential and morphological structures of passion fruit albedo (Passiflora edulis)

“…The flour presented a much higher amount (377.36 mg/100 g) than that found in fresh albedo (94.34 mg/100 g). These results were higher compared to the research by Miller et al (2020) with melon rinds that obtained in the flour (29.3 mg/100 g) content four times higher than that found in the flavedo/albedo (18 mg/100 g). Therefore, the flour had a significant content of vitamin C, and when considering its importance as an essential nutrient for human health, it can be used as an indicator of food quality, with its antioxidant properties and protection of the organism from oxidative stress.…”

“…This behaviour in the flour may be associated with the temperature to which this product was subjected to dehydration, since chlorophyll a is thermally more unstable than chlorophyll b (Pareek et al, 2017). In the study by Miller et al (2020), the melon rind showed higher values than this research. The content of chlorophyll a (57.50 ± 6.27 µg/g) was almost twice as high as that of chlorophyll b (30.36 ± 4.32 µg/g).…”

“…Different values when compared to our study can be attributed to the analysis method used in our research (spectrophotometry), which differed from the method used by Reis et al (2018) (highperformance liquid chromatography). In addition, other fruits present higher amounts in their byproducts and flours than in this study, as in the skins melon (364.01 μg g -1 ) (Miller et al, 2020) and pomelo (241 mg AGE/100 g) (Rodrigues et al, 2021) as well as in the peel flours yellow passion fruit albedo (0.64 mg GAE/g) (López-Vargas et al, 2013), Tanduk banana (54.60 mg GAE/g) (Bakar et al, 2018), and mango (83.72 mg AGE/g) (Chagas et al, 2020).…”

“…Phenolic compounds are secondary metabolites produced in fruits and are not evenly distributed in tissues (Miller et al, 2020). In yellow passion fruit, the concentrations in the peel (1061.87 mg AGE/100 g) were much higher than those in the seed (346.69 mg AGE/100 g) (Reis et al, 2018).…”

Environmentally Friendly Hydrothermal Processing of Melon by-Products for the Recovery of Bioactive Pectic-Oligosaccharides

“…Several studies focused on the recovery of the phenolic fraction by conventional alcoholic extraction [ 8 , 14 , 40 ], aqueous wet grinding [ 41 ] or ultrasound assisted extraction [ 42 ] have also been reported. More recent studies [ 11 , 43 ] evaluated the extraction of bioactive compounds (total phenolics, chlorophylls, total carotenoids and vitamin C) from several melon parts by ultra-turrax homogenization in alcoholic media.…”