Preliminary Data of the Nutritive, Antioxidative, and Functional Properties of Watermelon (Citrullus lanatus L.) Flour and Seed Protein Concentrate

Abstract

The growing interest in a plant-based diet leads to the search for new sources of protein in the human diet as an alternative to animal proteins. Plant materials that can supplement protein as additives in food products are being studied. Watermelon seeds (Citrillus lanatus L.) are rich in proteins and waste from the food industry; however, their extraction is not completely cost-free, and the flour production process may involve additional costs related to their extraction and processing. The studies showed that watermelon seed protein concentrate, obtained using the alkaline extraction method, contained 82.52 g/100 g of protein and 1.51 g/100 g of fat. The polyphenol content in the protein preparation from defatted watermelon seeds was 1.9 mg gallic acid/g, and the antioxidant activity of the concentrate was 29.26 µmol Trolox/g (by the ABTS+). The obtained watermelon seed protein concentrate was characterised by solubility of more than 80% (at pH = 10), water absorption at the level of 2.46 (g water/g) and oil absorption equal to 2.1 (ml oil/g), showed poor foaming properties (1.51%), and was characterised by low emulsification.