Date (Phoenix dactylifera) seed is a potential source of natural antioxidants, and the use of innovative green and low temperature antioxidant recovery techniques (using CO₂ as solvent) such as supercritical fluid (SFE) and subcritical (SubCO₂) extractions can improve their yields and quality in the extracts. SFE, SubCO₂ and Soxhlet techniques were employed to enrich antioxidants in extracts from Sukari (SKSE), Ambara (AMSE), Majdool (MJSE) and Sagai (SGSE) date seeds. Extract yields were evaluated and modelled for SFE extract using response surface methodology. Significantly higher (p < 0.05) phenolics (143.48–274.98 mg GAE/100 g), flavonoids (78.35–141.78 mg QE/100 g), anthocyanins (0.39–1.00 mg/100 g), and carotenoid (1.42–1.91 mg BCE/100 g) contents were detected in extracts obtained using SFE and SubCO₂ methods. The evaluation of in vitro antioxidant properties showed that SFE and SubCO₂ seed extracts demonstrated promising antioxidant (13.42–23.83 µg AAE/mL), antiradical (228.76–109.69 µg/mL DPPH IC₅₀), ferric reducing antioxidant power (1.43–2.10 mmol TE/100 g) and ABTS cation scavenging (375.74-717.45 µmol TE/100 g) properties that were significantly higher than Soxhlet extracts. Both SFE and SubCO₂ techniques can be effectively utilized as innovative and environmentally friendly alternatives to obtain high quality antioxidant rich extracts from date seed. These extracts may have potential functional and nutraceutical applications.

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.

The bioactive compounds of four Saudi date flesh extracts (Ambara (AF), Majdool (MF), Sagai (SF), and Sukkari (SKF)) prepared using different extraction methods—namely, supercritical fluid extraction (SFE), subcritical CO₂ extraction (SCE), and Soxhlet extraction (SXE)—were evaluated. A total of 19 bioactive compounds were detected in extracts prepared using SFE and SCE methods, whereas less than 12 compounds were detected in extracts obtained using the SXE method. Both the date variety and extraction method affected the phenolic profile of date flesh extract (p ≤ 0.05). The apparent viscosity, surface color, and bioactive properties of yogurt were affected by both date flesh extracts and storage duration in varied magnitudes (p ≤ 0.05). The incorporation of date flesh extracts into yogurt formulations increased the total phenolic content (TPC), DPPH antiradical activity, viscosity, and redness (a*) and decreased the lightness (L*) and yellowness (b*) of the developed product (p ≤ 0.05). The elongation of storage time progressively (p ≤ 0.05) reduced the pH, TPC, DPPH antiradical activity, bacterial counts, and L* and b* values and increased the acidity, syneresis, viscosity, and a* values with few exceptions. Date flesh extracts can improve the health quality of yogurt without major influence on the sensory attributes while stored at 4 °C.