Upcycling of melon seed (Cucumis melo L.) oil processing by-product: evaluation of functional properties and nutritional components as novel ingredient

BackgroundDefatted melon seed, a major by-product from melon oil processing chain, is scarcely utilsed. However, it has high potential value and can be used as novel ingredient in food products production. In line with zero waste policy and food sustainability, exploring and utilisation of this oil processing by-product can reduce food waste, and is key to moving towards a more sustainable food system. Therefore, this study aimed to assess the nutritional profile and functional properties of three varieties of defatted melon seeds (Galia, Cantaloupe, and Honeydew), and then compare them with defatted pumpkin seeds (as control group). ResultsIn this study, three varieties of melon seeds (Galia, Cantaloupe, and Honeydew) and pumpkin seeds (as control group) were defatted using Soxhlet extraction with petroleum ether; subsequently, their functional properties and nutritional components were assessed. The defatted melon seeds contained high level of protein (51.1-54.2%, w/w), dietary fibre (29.4-33.2%, w/w), potassium (1181.0-2373.1 mg/100 g), and GABA (gamma-aminobutyric acid, 1.4-4.3 mmol/kg), whereas in terms of anti-nutritional compounds, they contained a relatively high amount of phytic acid (5.0%-5.8%, w/w). They also exhibited good in water/oil absorption capacity and emulsifying capacity. The phenolics were mainly free phenolics (FP) fraction (75%-77%), followed by the conjugated phenolics (CP) fraction (15%-16%), and the bound phenolics (BP) fraction (about 8%); the antioxidant capacity of each fraction followed the same sequence (FP > CP > BP). ConclusionConsidering the nutritional composition, functional properties, and the presence of potentially bioactive compounds, defatted melon seeds have considerable potential to be used as a functional food ingredient for the reformulation of foods.