Solvent Extraction Techniques for Vegetable Oils

Solvent extraction remains the predominant industrial method for isolating oil from oilseeds and fruit kernels, owing to its high throughput and capacity to deliver oils with consistent yields and quality parameters. Conventional processes typically use petroleum-derived solvents such as n-hexane under controlled temperature, pressure and solvent-to-solid ratio. However, concerns over toxicity, flammability and environmental impact have stimulated a shift towards greener alternatives. Ethanol and mixed solvent systems offer lower toxicity and ease of solvent recovery, while advanced approaches such as pressurised liquid extraction and subcritical fluid extraction enhance mass transfer rates and reduce extraction times. Recent developments integrate solvent selection with process intensification strategies—optimising particle size, agitation, temperature and pressure—to balance extraction kinetics, thermodynamics and product purity. Techniques such as cold demixing of ethanol miscella, use of natural deep eutectic solvents and response surface methodology for process optimisation have broadened the toolkit for obtaining high-quality oils and valuable co-products. Emphasis on circular economy principles has driven valorisation of residual cakes, enabling extraction of remaining lipids and recovery of protein-rich meals. Together, these innovations underpin a more sustainable and resource-efficient vegetable oil industry with applications spanning food, cosmetic, pharmaceutical and biofuel sectors.

Research from Nature Portfolio

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Research from all publishers

Recent investigations have demonstrated the efficacy of mixed solvent systems for rice bran oil extraction, employing response surface methodology to determine optimal solid-liquid ratios, temperature and extraction time. Under these conditions, an engineered solvent blend achieved over 85 % oil yield while preserving valuable constituents such as γ-oryzanol and phytosterols. Parallel work has explored pressurised liquid extraction of soybean by-products using natural deep eutectic solvents. By combining choline chloride with organic acids and water under moderate pressure and temperature, researchers obtained phenolic-rich and lipid-rich fractions in a single step, highlighting the promise of deep eutectic mixtures as low-toxicity, biodegradable alternatives to conventional solvents. In the Amazonian context, techno-economic studies on Buriti semi-defatted cake have shown that anhydrous and aqueous ethanol can recover residual lipids effectively, enhancing overall oil yields and producing defatted cakes rich in proteins and carbohydrates. Economic modelling suggests that integrating such valorisation within existing facilities, supported by solvent recovery loops and good processing practices, can be both sustainable and commercially viable, especially under favourable market and policy frameworks.

Solvent Extraction Techniques for Vegetable Oils publication trend

The graph below shows the total number of articles in solvent extraction techniques for vegetable oils across all publications each year (not limited to Nature Index journals).

Technical terms

Response Surface Methodology: A statistical technique for designing experiments and modelling the effects of multiple process variables on extraction performance.

Pressurised Liquid Extraction (PLE): A method that uses elevated temperature and pressure to improve solvent penetration, accelerating mass transfer and reducing extraction time.

Natural Deep Eutectic Solvent (NADES): A designer solvent composed of two or more natural components that form a eutectic mixture, offering tunable polarity and low toxicity for green extraction.

Miscella: The homogeneous solution of oil dissolved in solvent during extraction, from which oil is later separated by phase demixing or distillation.

References

1. Valorization of Amazonian buriti (Mauritia flexuosa) semi-defatted residual cake as a circular economy strategy: A techno-economical analysis. Industrial Crops and Products (2025).
2. Improved rapeseed oil extraction yield and quality via cold separation of ethanol miscella. OCL - Oilseeds and fats, Crops and Lipids (2018).
3. Optimization of Oil Extraction from Rice Bran with Mixed Solvent Using Response Surface Methodology. Foods (2022).
4. Pressurized natural deep eutectic solvents: An alternative approach to agro-soy by-products. Frontiers in Nutrition (2022).