Watermelon seeds and peels: fatty acid composition and cosmeceutical potential

Abstract

Watermelon consumption results in generation of organic waste in the form of seeds and peels. We have evaluated the fatty acid profiles and antioxidant content of watermelon (Kinnaree cultivar) seed oil and peel wax. In addition, we assessed the potential use of these watermelon industry byproducts in the development of cosmeceuticals. The most abundant fatty acids in seed oil and peel wax were linoleic acid and arachidic acid, respectively. Fatty acids form an essential component in the cell membranes and have seen increased recognition in the cosmeceutical industry. Antioxidants also play a beneficial role in skincare in combating free-radicals resulting from sun damage and pollutants. The seed oil showed stronger antioxidant activity than the peel wax, as indicated by the DPPH radical scavenging ability of 0.894 mg α-tocopherol equivalent/g dried seeds versus 0.036 mg α-tocopherol equivalent/g dried peels. Therefore, the seed oil was formulated into skincare products, in the form of emulsions and nanoemulsions. The most effective formulae were stable at room temperature for seven days, or following repeated cycles of heating and cooling. This work demonstrates the potential for watermelon seed oil to be employed in skincare product formulations, which could maximize agricultural profit and minimize environmental waste.

Recent trends in preprocessing and extraction of watermelon rind extract: A comprehensive review

“…Lee and Choo (2020) had a similar opinion by suggesting a small cutting size of 3 cm × 3 cm for 60°C oven drying. As for watermelon rind drying conditions, Petchsomrit et al (2020) used hot air oven drying at 60°C until a constant weight was obtained for lipid extraction, whereas Lee and Choo (2020) applied a temperature of 60°C for 24 h for pectin extraction. Higher temperature and longer drying time were used as watermelon rind contains high water content.…”

“…As the mesh size increases, the size of the opening decreases, resulting in more refined the particles. Homogenized and finer particle size significantly results in a better contact area with extraction solvents, thus optimizing the extraction process (Petchsomrit et al, 2020). Figure 2 shows the effect of increasing surface area on the extraction yield.…”

“…The process is suitable for extracting fresh samples with readily soluble bioactive components (Abubakar & Haque, 2020). A study by Petchsomrit et al (2020) evaluated the effect of different extraction durations (2, 6, 12, and 24 h) on the watermelon rind sample using hexane (1:5 w/v). The finding showed that the extraction yield increases as the longer extraction time is applied.…”

“…The finding showed that the extraction yield increases as the longer extraction time is applied. The extraction time of 24 h was the most efficient to extract fatty acids compound in the watermelon rind sample with a 1.155% yield compared with 0.187% at 2 h (Petchsomrit et al, 2020).…”

“…According to Ramakrishnan et al (2020), watermelon flesh contributed to 68% (w/w) of overall fruit mass, 30% (w/w) is watermelon rind and the other 2% (w/w) is leftover. Watermelon rind contains carbohydrates, fiber, and wax (Petchsomrit et al, 2020). Ramakrishnan et al (2020) also reported that watermelon rind consists of 13% (w/w) pectin, 10% (w/w) lignin, 23% (w/w) hemicellulose, and 20% (w/w) cellulose.…”