Innovative and Green Extraction Techniques for the Optimal Recovery of Phytochemicals from Saudi Date Fruit Flesh

Abstract

Saudi Arabia is one of the major producers of date (Phoenix dactylifera) fruit. Date fruit flesh is considered a healthy food due to the presence of natural antioxidants. Green and innovative supercritical fluid (SFE, 52.5 °C temperature, 27.50 MPa pressure, 5 mL CO2/min flow rate) and subcritical (SubCO2, 250 extraction cycles, 29 °C temperature, 6.8 MPa, 12 h, ethanol solvent) extraction techniques were used to produce flesh extracts from four Saudi date fruits (Sukari (SKFE), Ambara (AMFE), Majdool (MJFE) and Sagai (SGFE)), and extracts prepared using 6 h Soxhlet extraction at 70 °C for 16 h using n-hexane as solvent, were taken as control. SFE produced the highest (p < 0.05) extract yields, whereas the SubCO2 method recovered significantly higher (p < 0.05) amounts of phytochemicals. Total phenolics (186.37–447.31 mg GAE/100 g), total flavonoids (82.12–215.28 mg QE/100 g), total anthocyanins (0.41–1.34 mg/100 g), and total carotenoid (1.24–2.85 mg BCE/100 g) were quantified in all the flesh extracts. The biological properties evaluation showed that flesh extracts had high antioxidant (17.79–45.08 µg AAE/mL), antiradical (191.36–34.66 µg/mL DPPH IC50), ferric-reducing (2.18–5.01 mmol TE/100 g) and ABTS-scavenging (444.75–883.96 µmol TE/100 g) activities. SubCO2 was the best technique and Majdool the best date variety, in terms of both phytochemicals and biological properties.