Essential oils: Advances in extraction techniques, chemical composition, bioactivities, and emerging applications

Essential oils are complex, unstable compounds processed from aromatic plants. They exhibit a wide spectrum of bioactive properties and are, therefore, routinely used in the food, pharmaceuticals, and cosmetics industries. This review approaches the essential oil extraction processes, their components, and basic biological and technological applications. The usual methods involve hydrodistillation, steam distillation, solid-liquid extraction, solvent extraction, cold pressing, and pressing. Most conventional methods produce disputes in the form of inefficiency and thermal degradation. Newer extraction methods include supercritical fluid extraction, molecular distillation, enzyme-mediated extraction, microwave-assisted hydrodistillation, and microwave-assisted extraction. These methods typically show more yields, selectivities, and sustainability. The bioactive profiles of essential oils mainly include terpenes (mono-, sesqui-, and diterpenes) alcohols, ketones, and esters accountable for their antimicrobial, antioxidant, anti-inflammatory, antifungal, and antiviral actions. Their applications have also extended to biodegradable packaging, food preservation, edible coating, microencapsulation, and nanoencapsulation. In spite of this, they are still hard to use in real life because of things like inefficient extraction, poor stability, and regulatory issues. Further research must be conducted in green extraction techniques, nanoformulation approaches increasing bioavailability, and their synergistic approaches with novel food technologies. If the trail of its modification in this direction is taken, this could guarantee rational use of such oil on a sustainable and effective scale.