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.