Introduction to Essential Oils

By Dr. Prabodh Satyal

Essential oils (EOs) are enjoying unprecedented popularity, but there is also growing confusion about what they are and what they are not. Many consumers and even some industry participants mistakenly label CO2 extracts, absolutes, concretes, and carrier oils as essential oils. This confusion not only affects market transparency but can mislead consumers and affect the credibility of natural product science. In this article, I want to clarify the definition of essential oils, highlight their historical and cultural significance, and provide insights into the evolving global EO market.

What Are Essential Oils?

According to Harrewijn et al. (2000), essential oils are complex mixtures of volatile compounds produced by living organisms and isolated by physical means such as distillation or pressing from botanically identified plant material. However, variations in extraction methods and interpretations have sparked debate.

To address this, the International Organization for Standardization (ISO 9235) established a widely accepted definition:

"Products obtained from natural raw materials, either by distillation with water or steam, or from the epicarp of citrus fruits by mechanical processes, or by dry distillation."

Essential oils are not obtained using solvents like ethanol or supercritical CO2. Therefore, CO2 extracts and absolutes do not qualify as essential oils under this standard.

The United States Pharmacopeia (USP) and European Pharmacopoeia (Ph. Eur.) align with this view. They define essential oils as volatile oils obtained exclusively by physical means such as steam or water distillation or cold pressing, typically from a botanically identified plant source. Solvent-based methods, including supercritical CO2 extraction, fall outside these official definitions.

So why shouldn’t CO₂ extracts be classified as essential oils?

While CO₂ extracts are valuable and often offer a more complete spectrum of plant compounds—including waxes, resins, and other lipophilic constituents—they do not meet the strict extraction criteria. The use of a solvent, even one as clean as CO₂, changes both the method and chemical profile, often resulting in a product richer in non-volatiles and lacking the same distillation-based chemical fingerprint.

Hence, to preserve scientific accuracy and regulatory integrity, CO₂ extracts should be labeled and marketed separately from essential oils.

Essential oils are stored in specialized glandular cells, ducts, or cavities in different parts of plants—leaves, bark, flowers, fruits, roots—and released by distillation, cold pressing, or dry distillation. Modern distillation methods, such as steam distillation and hydrodistillation, rupture these cells to release the aromatic compounds.

Biosynthesis and Biological Roles of Essential Oil Components

The complexity of essential oils comes from their biosynthetic origin:

1. Mevalonate Pathway: Sesquiterpenes and triterpenes

2. Methylerythritol Phosphate (MEP) Pathway: Monoterpenes and diterpenes

3. Shikimic Acid Pathway: Phenylpropanoids (e.g., eugenol, cinnamaldehyde)

4. Acetate Pathway: Fatty acid derivatives

These biochemical routes allow plants to create thousands of compounds with diverse structures and therapeutic properties—giving essential oils their distinctive aromas and bioactivities.

In addition to aroma, terpenes—which dominate EO composition—have multifaceted roles in biological systems:

• Functional Roles in Metabolism: Terpenoid-based vitamins (like A, D, E, and K) are critical for vision, bone health, antioxidant protection, and coagulation. Chlorophyll, a terpene-related molecule, enables photosynthesis.

• Defense Mechanisms: Terpenes act as natural antibiotics and fungicides in plants. They deter herbivores by making plants unpalatable or toxic (e.g., azadirachtin in neem, bufotalin in toads). Many are released in response to injury, helping seal wounds or repel invaders.

• Communication: Intraorganismal: Serve as signaling molecules within organisms, like gibberellic acid in plant growth or steroidal hormones in animals. Interorganismal: Function as pheromones or attractants/repellents. D-limonene deters termites. Geraniol attracts pollinators. Nepetalactone in catnip repels insects and stimulates behavioral responses in felines.

• Ecological Interactions: Terpenes mediate plant-plant communication (allelopathy). They influence microbial communities in soil or on leaf surfaces, shaping the plant microbiome.

These diverse functions explain why essential oil components are considered evolutionarily advantageous and ecologically indispensable—offering protection, reproduction, and biochemical adaptation to both plants and the organisms interacting with them.

Historical and Cultural Significance

Essential oils are rooted in traditional medicine, ritual, and healing practices for thousands of years:

• Ancient Egypt: Botanical extracts were used in mummification, perfumery, and temple rituals (Ebers Papyrus, ~1550 BCE)

• India: In Ayurveda, the concept of Gandhshastra (science of aroma) deeply integrates essential oils with spiritual and physical healing

• China: Over 4,000 years of aromatic herbal medicine

• Religious Texts: Oils and resins like frankincense and myrrh are referenced in the Bible, Quran, and Torah

• Ibn al-Baitar (13th century): First documented steam distillation method for essential oils

Even in Hindu culture, a powerful mantra captures the essence of EOs:

"सुगंधिं पुष्टिवर्धनं" (Sugandhim Pushtivardhanam)

• Fragrance that nourishes and sustains all life forms.

Current Uses and Applications

Essential oils are used across many industries, with widespread applications in:

• Wellness & Aromatherapy: Diffusers, massage oils, emotional well-being

• Pharmaceuticals: Active ingredients for antimicrobial, antifungal, and anti-inflammatory drugs

• Food & Beverage: Natural flavor enhancers in chewing gum, mints, baked goods, and beverages

• Cosmetics & Personal Care: Fragrances, anti-aging creams, serums, and shampoos

• Home Care & Cleaning: Disinfectant sprays, natural deodorizers, laundry products

• Veterinary & Agrochemical: Natural growth enhancers and pest deterrents

Although aromatherapy garners more attention in the wellness community, the flavor and fragrance (F&F) industry consumes nearly 60–70% of the global essential oil supply. In comparison:

• Aromatherapy & wellness: ~10–15%

• Cosmetics & personal care: ~10%

• Pharmaceuticals, agriculture, and other industrial uses: ~5–10%

This includes applications in processed foods, beverages, oral care, perfumes, and personal care products—making F&F the dominant sector in EO consumption.

Global Market Landscape

The EO market is expanding rapidly, driven by consumer demand for clean-label and plant-based products.

• 2024 Global Market Size: Estimated at $11–13 billion USD

• CAGR (2024–2030): 7–9% annually

Top Producing Countries:

• India (Mint, lemongrass)

• Brazil (Orange, copaiba)

• Indonesia (Patchouli, citronella)

• China (Eucalyptus, Camphor)

• USA (Birch, peppermint)

Major Buyers:

• F&F giants (Givaudan)

• EO brands (doTERRA)

• Cosmetic & pharma companies

Trends:

• Rise of CO2 extracts, absolutes, and hydrosols

• Increasing concerns around adulteration

• 100% pure and natural Emphasis on sustainability and traceability

Conclusion: The Future of Essential Oils

Essential oils are more than just aromatic compounds—they are an intersection of culture, science, and commerce. But as their popularity grows, so does the responsibility to protect authenticity, ensure sustainability, and educate the public.

By understanding what essential oils truly are—and what they are not—we can uplift this ancient science with modern integrity.

Dr. Prabodh Satyal Essential Oil Scientist | Purity Analyst | EO Educator

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