Impact of Using Different Extractions Methods (Conventional and Enzymatic Techniques) on Watermelon Seeds Oil Characterization and Stability

Abstract

Watermelon seed oil (WMSO) is an interesting and promising rich source of bioactive molecules and unsaturated fatty acids, which is of great interest for both human nutrition and industrial applications. The objective of this study was to investigate the effect of different extraction methods (Soxhlet (SOE), cold pressing (COPE), and aqueous enzymatic extraction (AEE)) on the yield, physicochemical quality, and bioactive components of WMSO. The oil yield was obtained as the highest (38.41%) from SOE, followed by COPE (32.17%) and AENE (30.29%). The fatty acid profile showed that linoleic acid (C18:2) was the major fatty acid (63.80–69.90%), followed by oleic acid (C18:1, 13.45–16.92%), whereas AENE also had the highest U/S ratio (5.50). Meanwhile, tocopherol was most abundant in AENE (221.17 mg/kg), followed by COPE (203.51 mg/kg) and SOE (196.07 mg/kg), and the carotenoid was better retained in COPE (28.07 mg/kg). Regarding the composition of phytosterols, it was re-vealed that β-sitosterol (171.89-177.74 mg/100 g) was the major phytosterol, and the total phytosterol of SOE was the highest (341.32 mg/100 g). The total phenolic content and antioxidant activity of SOE (75.62 mg GAE/100 g, 74.11%) were significant-ly higher compared with AENE, and AENE was significantly higher compared with COPE. AENE-extracted oil had better oxi-dative stability during storage. In summary, the extraction procedure plays a crucial role in the yield, composition, and stability of WMSO. Thus, the AENE produced oils having relatively greater tocopherols, and stability, rendering it as a potentially nature-friendly technique for functional and industrial uses.