Enhanced sustainable supercritical CO₂ extraction using anti-channeling agents for high oil yield and protein quality in canola meal

Abstract:
Supercritical CO₂ (SCCO₂) extraction offers an eco-friendly alternative for extracting oil from canola seeds as it avoids solvents and preserves the meal’s nutritional and functional quality. This study developed a method combining expeller pressing with SCCO₂ to achieve a 99.9% oil yield, resulting in a solvent-free, de-fatted canola meal suitable for plant-based applications. While a completely de-fatted meal is often preferred for plant-based products, this approach also allows producing meals with varying oil residues to accommodate applications benefiting from residual oil.
Particle size was optimized, with a 710-micron sieve providing the highest oil recovery (53±0.6%) over 260 minutes at 60°C and 400 bar. Anti-channeling agents, namely glass beads and charge sleeves, enhanced extraction efficiency by evenly distributing SCCO₂ within the vessel. These agents increased yield significantly to 79±1% compared to 53±0.6% without them. Extending extraction time to 330 minutes at a flow rate of 25 g/min further maximized yield, achieving 99.9±0.1%. ANOVA, followed by Dunnett's multiple comparisons test, showed this yield significantly surpassed the expeller-only method (86.6±0.1%) and slightly exceeded the hexane method (99.1±0.2%). The total amino acid composition of the SCCO₂-extracted meal was 38 g/100 g, and the amino acid score exceeded 100%, indicating no deficiencies in indispensable amino acids and confirming its high nutritional quality, surpassing hexane-extracted (36 g/100g) and expeller-pressed (33 g/100g) meals. In vitro protein digestibility (IVPD) reached 88%, higher than soybean (83%) and peas (73%). Techno-functional properties included a water-holding capacity of 1.7 g/g and oil-holding capacity of 1 g/g for meal with 0.1% oil residue, outperforming meals with 50% oil residue. High foaming stability (93%) and an emulsifying activity index of 34 m²/g demonstrated the meal's enhanced quality.
This green extraction method for canola meal maximizes oil recovery while preserving protein functionality, supporting sustainable, high-quality food production and meeting demand for plant-based proteins.