ISSUE FOCUS FEED & ADDITIVE MAGAZINE September 2024 31 years ago. Today, it represents an established and technical term in scientific literature, referring to plant-derived, bioactive substances. Among these, essential oils (EO) are notable for their wide range of applications, including traditional medicine, cosmetics, perfumes, and more. Essential oils are volatile, fragrant compounds extracted from plants. They are oily (though not fats), lipophilic, water-repellent, highly volatile, and odorous. The color of EO varies based on the plant source, which can be, among other, leaves (rosemary), branches (tea tree), stems (lemongrass), bark (cinnamon), roots (vetiver), rhizomes (ginger), bulbs (garlic), fruits (orange), seeds (anise), flowers (jasmine), or plant tops (thyme). Essential oils are characterized by their plant origin (e.g., essential oil of Thymus vulgaris), the plant part used, and specific active compounds. CHEMICAL COMPOSITION OF ESSENTIAL OILS EOs are composed of aromatic molecules with specific chemical structures. They are synthesized from different pathways: • Terpenoids: Molecules with isoprene units, synthesized from the acetyl-CoA pathway. Examples include limonene, pinene, menthol, and geraniol. • Phenylpropanoids: Molecules with benzene rings, synthesized from phenylalanine. Examples include thymol, carvacrol, eugenol, and cinnamaldehyde. Secondary metabolites are produced by plants for protection against pests, pathogens, and environmental stressors, to inhibit the growth of competitive plants, or to attract pollinators and seed dispersers. Secondary metabolites are present in the oils obtained by extraction from plants. The concentration of these metabolites in EOs varies based on growth conditions, development stage, and weather. EXTRACTION, ENCAPSULATION, AND ANALYSIS OF ESSENTIAL OILS EOs are mainly produced by distillation. The methods include: • Water Distillation: Plants are mixed with water and heated directly. • Steam Distillation: Plants are heated with steam. • Water-Steam Distillation: Plants are mixed with water and heated by steam. For citrus plants, essential oils are extracted from Delicate flower petals in water Heat Water and essential oils WATER Floral waters Separator Condenser Essential oil Figure 2. EO distillation with water distillation methodology for non-sensitive plant
RkJQdWJsaXNoZXIy MTUxNjkxNQ==