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Vegetable oils or vegetable fats, are oils extracted from seeds or from other parts of plants. Like animal fats, vegetable fats are mixtures of triglycerides. In common usage, vegetable oil may refer exclusively to vegetable fats which are liquid at room temperature.
Essential oils are also known as volatile oils, ethereal oils, aetherolea, or simply as the oil of the plant from which they were extracted, such as oil of clove. An essential oil is "essential" in the sense that it contains the "essence of" the plant's fragrance—the characteristic fragrance of the plant from which it is derived.
Types and composition
The majority of vegetable oils consist of triglycerids of palmitic, oleic, linoleic acids, in various percentages. These types of oils are commonly used as cooking oil and are generally edible. Triglycerides of less common fatty acids, such as ricinoleic acid are not suitable for consumption and are instead used in industry.
The most common vegetable oils used are sunflower oil, olive oil, soybean oil, peanut oil, castor oil, etc., since they're very cheap and thus readily available, although the price and availability depends on the region. Countries where olives are grown in large amounts will use more olive oil than other types of oil. This is also true for other vegetable oils.
Many vegetable/essential oils contain various useful reagents in high concentration, either as free compound or locked in triglyceride:
- Ajwain oil: Thymol (35–65%)
- Bitter almond oil: Benzaldehyde (~90%)
- Castor oil: Ricinoleic acid (85–95%, as triglyceride)
- Cinnamon bark oil: Cinnamaldehyde (~90%)
- Clove oil: Eugenol (82–88% in clove leaf oil, 80–90% in clove bud oil, 90–95% in stem oil)
- Eucalyptus oil: Eucalyptol (90%)
- Lavander oil: Linalool (28-49%), Linalyl acetate (~32%), Eucalyptol (~25%), Camphor (~13%)
- Orange oil: Limonene (90-95%)
- Sassafras oil: Safrole (~90%)
- Tea tree oil: 4-Terpinol (35-48%)
- Wintergreen oil: Methyl salicylate (98%)
Oils are viscous colorless or yellowish or brown liquids, that are not miscible with water, but more miscible with organic solvents. They have various odors, ranging from mild to strong. Some oils, like palm and coconut oil are solid near room temperature and will melt in hot weather.
Vegetable oil is sold in most food stores and natural product stores, as well as pharmacies and similar stores.
Most vegetable oils have no legal restrictions, though in US, bitter almond oil is restricted, since it's essentially crude benzaldehyde, which is List I drug precursor and thus cannot be acquired without paperwork. This restriction does not apply to other countries where benzaldehyde is not restricted as drug precursor.
Likewise, brown camphor and sassafras oil contain safrole, which is also List I chemical due to its use in the production of MDA and MDMA, meaning the sale of this oil is restricted.
Vegetable and essential oils can be extracted through various means.
Handling and safety
Vegetable oil is non-toxic and may be used in cooking. However, many types of oil, like castor oil is not fit for consumption. Other oils, such as sassafras oil is suspected to cause cancer.
Due to their susceptibility to oxidation from the exposure to oxygen, heat and light, resulting in the formation of oxidation products, such as peroxides and hydroperoxides, plant oils rich in polyunsaturated fatty acids have a limited shelf-life.
Relevant Sciencemadness threads
- Transesterification of vegetable oil and ethanol
- Could I just use some kind of cooking oil for defatting?
- Boiling point of oils (vegetable & motor mostly)
- Extraction of liquid fatty acids from vegetable oil
- Essential Oil Extraction
- Essential Oils
- essential oil hydrodistillation general questions
- Oil extraction from plant matter - "regular" oil vs "essential" oil