OIA2007 VOLATILE OILS

Definition of Volatile Oils

Volatile oils (essential oils) are aromatic oily substances obtained from various parts of plants (e.g., leaves, flowers, roots).

Volatility

Unlike fixed oils, volatile oils evaporate at room temperature and leave no greasy residue

Physical Properties

Odorous, volatile, non-greasy, can resinify when exposed to air.

Chemical Constituents

Include alcohols, aldehydes, phenols, esters, ketones, hydrocarbons.

Examples of Volatile Oils

Citronella oil, lavender oil, clove oil, eucalyptus oil, tea tree oil.

Volatile Oils vs Fixed Oils

Volatile: Terpenoids, evaporate, resinify, used medicinally (e.g., clove oil).

Fixed: Triglycerides, non-volatile, turn rancid (e.g., olive oil, sunflower oil).

Methylerythritol Pathway (MEP)

Produces monoterpenes & diterpenes.

Mevalonate Pathway (MVA)

Mevalonate Pathway (MVA)

Shikimic Acid Pathway

Leads to phenylpropenes (e.g., eugenol in clove).

Terpenoid Classifications

C5: Hemiterpenes

C10: Monoterpenes

C15: Sesquiterpenes

C20: Diterpenes

C30: Triterpenes

C40: Carotenoids

Gas Chromatography-Mass Spectrometry (GC-MS)

Gold standard for qualitative analysis of volatile oil components.

Plant Example in GC-MS

Blumea balsamifera (analyzed via GC-MS for essential oil profile).

Oil Storage Locations

Stored in glands, ducts, cavities, glandular hairs.

Oil Association with Other Compounds

Often found with gums, resins, etc.

Hydrodistillation (Traditional)

Plant boiled in water, steam carries oil → cooled and separated.

Clavenger Apparatus

Used in hydrodistillation to collect oil layer above water.

Solvent-Free Microwave Extraction (SFME)

Rapid, green method, maintains sensitive compounds.

Cold Pressing

Mechanical, low heat → used for citrus peels, preserves integrity.

Enfluarage

Delicate method using odorless fat to absorb scent, then alcohol to extract.

Supercritical Fluid Extraction (SFE)

Uses CO₂ under pressure, efficient but expensive.

Hydrodistillation Process Steps

Boil → Condensation → Separation → Drying with Na₂SO₄ → Rotary evaporation.

Hydrodistillation Drawbacks

Slow, heat-sensitive compounds may degrade, not scalable.

Antimicrobial Activity

Effective against bacteria, fungi (e.g., tea tree oil).

Anti-inflammatory Effect

E.g., eucalyptus oil for respiratory inflammation.

Antiviral & Anticancer Activity

Limonene (from citrus) shows anticarcinogenic properties.

Digestive Support

Lavender oil aids digestion, reduces bloating.

Aromatherapy

Oils used to relieve stress, anxiety, insomnia (e.g., lavender, peppermint).

Cosmetics & Perfumes

Base ingredient due to aromatic nature.

Household Products

Disinfectants, air fresheners (e.g., lemongrass oil).

Food Industry

Natural flavoring agents (e.g., clove oil in dental gels).

Agricultural Use

Insecticides, herbicides derived from essential oils.

Plant Defense Role

Protect against herbivores, insects, microbes.

Attract Pollinators

Oils act as pheromones or attractants.

Reduce Water Loss

Oils form protective layers → prevent desiccation.

Eugenol (Phenylpropanoid)

Found in clove oil, used as analgesic in dental care.

Menthol (Monoterpene Alcohol)

Found in peppermint oil, cooling effect.

Citral (Monoterpene Aldehyde)

Found in lemongrass oil, antibacterial, antifungal.

Cineole (Monoterpene Ether)

Found in eucalyptus oil, respiratory aid.

Storage Tips

Store in amber glass, cool dry place, protect from light and air to avoid degradation.