Sustainable techniques for extracting essential oils from spices and herbs: A comprehensive review

This review emphasizes innovative techniques for extraction of essential oils, including ultrasound-assisted, supercritical fluid, enzyme-assisted, pressurized liquid, and microwave-assisted extraction methods. An analysis is performed on fundamental operational characteristics highlighting its advantages and limitations in terms of environmental impact, selectivity, and efficiency. Supercritical fluid extraction uses supercritical carbon dioxide in a solvent-free approach, enabling control of solvating capacity to obtain high-purity extracts. This technique facilitates extraction of essential oils from spices such as turmeric and clove. Enzyme-assisted extraction breaks down cell walls and promotes release of essential oils from black pepper and cardamom using specific enzymes such as cellulase and protease. Pressurized liquid extraction uses increased temperatures and pressures to enhance penetration and solubility of solvents. Application of ultrasound and microwaves effectively enhances mass transfer rates and reduces extraction periods utilizing ultrasonic and electromagnetic radiation. This investigation contributes to efficient, eco-friendly, and cost-effective methods for essential oil extraction.