TECHNOLOGICAL STRATEGIES FOR THE USE OF WATERMELON AS A SOURCE OF BIOACTIVE MOLECULES AND ANTIOXIDANT PIGMENTS

Watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) is a well-known refreshing and thirst-quenching typical summer fruit. It has attracted considerable interest for the presence of lycopene and citrulline, biomolecules with undisputed health-promoting effects. Numerous epidemiological studies have revealed the involvement of lycopene in prevention of many degenerative diseases, including arteriosclerosis, diabetes and cancer, likely acting as antioxidant and/or through still poorly understood different molecular mechanisms [1]. Likewise, citrulline, a water-soluble, non-essential amino acid, was recently claimed as having great potential in prevention and treatment of Alzheimer's disease, dementia, erectile dysfunction, high blood pressure, diabetes and, as food supplement, in improving athletic performance [2]. Given the nutritional importance of these bioactive molecules, the preparation of natural concentrated extracts, useful as high-value ingredients for the production of nutraceuticals and/or pharmaceuticals, could represent a viable alternative to the usual production and distribution chain of watermelon and a sustainable process for non-marketable fruits and processing byproducts valorization, opening new opportunities for agri-food industry development. In the last decades the interest towards green, environmentally friendly and safe extraction technologies has strongly increased. Supercritical CO2 extraction has been successfully used to obtain lycopene containing oleoresins from freeze-dried tomato matrices [3,4]. The homogenized flesh of red watermelon (cv. Dumara) peponides was centrifuged to prepare a lycopene rich freeze-dried matrix suitable for supercritical CO2 extraction from the pellet and a citrulline containing powder from the supernatant. The optimal physico-chemical parameters to maximize lycopene extraction yields from the watermelon matrix have been identified. The presence of lipids from watermelon seeds in the matrix has a positive effect on oleoresin extraction. The addition of an oleaginous co-matrix consisting of roughly grinded hazelnut seeds did not further increase the extraction yield. The use of ethanol as co-solvent resulted in a significant increase in lycopene extraction but not of citrulline. The biochemical analyses showed that the extract is a healthy and high added-value source of lycopene and other valuable lipophilic antioxidants useful as bioactive color additive in functional food, nutraceutical, cosmeceutical and pharmaceutical formulations.