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What are plant oils?

We all know plant oils are oils that come from plants, don’t we?

While that indeed is true, you will be truly amazed to discover the range of oils derived from plants and trees.

Allow us to elaborate. Now, you and I know that a plant/tree comprises the following: root, stem, leaves, flowers, seeds, fruits, have we left something out? The interesting fact is, many parts of each plant can provide us with extracts and derivatives that are useful.

Can you imagine that most parts of the docile-looking tree or plant that grows right next to your house could be providing mankind with beneficial oils, extracts or derivatives? And if one starts counting the various different plants and trees all over the world, the magnitude and variety of the oils and extracts that can be derived from them appears truly admirable.

Plant-derived oils can be broadly classified into two: Essential Oils & Fixed Oils.

Essential oils are volatile, and are usually derived from the non-seed parts of the plants, while most fixed oils are the so-called “fatty oils”, and a majority of the fatty oils are derived from the seeds.

Essential oils have been used for centuries. They have been used extensively in ancient Rome, Greece, Egypt & the Middle East – as perfumes, flavours, deodarants, antiseptics & pharmaceuticals. As a result of new processing technologies, they can today used for more functions as well.

The use of fixed oils or “fatty oils” are more recent, but they have become as important as, or more important than, their essential oil counterparts, as edible oils, as industrial raw materials and feedstock for producing a number of useful products.

As mentioned above, most fixed oils are derived from the seeds – hence the term oilseeds, meaning oil-bearing seeds. Some of the fixed oils are derived from vegetables & nuts.

This page tries to capture the magic of all the benefits that plants and trees provide us through their oils. While the focus is on comprehensive info with regard to plant oils, the page also provides brief details of the other extracts and derivatives from plants.

In addition to details and inputs, The Plant Oils Database also contains a comprehensive listing of sites related to plant oils and plant derivatives. Our researchers have gone through thousands of web pages and picked out sites and pages that we felt could be relevant and interesting

Oilseeds & Fixed Oils

Fixed oils are oils obtained from plants that are fatty, dense and non-volatile, such as olive and sweet almond oil. This is in contrast to essential oils which are volatile in nature. Some of the prominent fixed oils are almond oil, castor oil, coconut oil etc. The term vegetable oils is normally used interchangeably with the term fixed oils. Fixed oils are derived from seeds, nuts & vegetables.

The major oilseeds are soybeans, rapeseed, cottonseed, sunflowerseed, groundnut, palm, copra (dried coconut), sesame, linseed & castorseed, maize oil and coconut oil. Others include peanut, cottonseed, olive oil, hemp, corn, mustard & flaxseed. ( see here for worldwide statistics of major oilseeds)

Fixed Oils & Oilseeds Links

• Oilseeds Group – USDA
• Australian Oilseeds Federation
• FAPRI International Oilseeds Model
• Directorate of Oilseeds Research – Indian Council of Agricultural Research
• Eastern Cereal & Oilseed Research Centre, Canada
• Natural Resources Institute – Oilseeds Research
• International Association of Seed Crushers
• Oilseeds Info & Statistics from Fediol
• Castor Oil Sourcing Directory
• Indian Oilseeds and Produce Exporters Association
• Oilseeds Links from University of Texas
• Oilseeds Links from United Oilseeds
• National Oilseeds Processors Association
• National Cottonseed Products Association
• Small-scale Processing of Oilfruit & Oilseeds (PDF)
• Health Benefits of Commodity Crops - Oilseeds (PDF)
• Oilseeds Then & Now (PDF)
• Vegetable Oils – from Wikipedia

Links for the Major Oilseeds

• Rapeseed - Rapeseed – from Wikipedia, Rapeseed/Canola Info from Purdue University, Rapeseed Info – from AgMRC
• Soybeans - Soybeans – from Wikipedia, Soy Information Clearinghouse
• Sunflower Seed - Sunflower Seed – from Wikipedia, Canada’s Sunflower Seed Industry (PDF)
• Peanuts - Peanuts – from Wikipedia
• Cottonseed - US Cottonseed Products Association, Cottonseed Oil – from Wikipedia
• Palm Oil - Palm Oil – from Wikipedia, Malaysian Palm Oil Board
• Olive Oil - Olive Oil – From Wikipedia, International Olive Oil Council

The Complete List of Vegetable Oils

The following vegetable oils account for almost all world-wide production, by volume.

• Corn oil, one of the most common cooking oils
• Cottonseed oil, a major food oil, often used in industrial food processing
• Canola oil/Rapeseed oil, one of the most widely used cooking oils, from a (trademarked) cultivar of rapeseed
• Olive oil, used in cooking, in cosmetics, for soap-making and as a fuel for traditional oil lamps
• Palm oil, the most widely produced tropical oil.
• Palm kernel oil - from the seed of the African palm tree
• Peanut oil/Ground nut oil, a mild-flavored cooking oil
• Safflower oil, a colorless & odorless cooking oil
• Sesame oil
• Soybean oil, accounts for about half of worldwide edible oil production
• Sunflower oil, a common cooking oil

The less major vegetable oils include

• Almond oil, from the almond nut
• Apricot oil, from the seeds of the apricot
• Argan oil
• Avocado oil
• Ben oil, from Moringa oleifera
• Cashew oil
• Castor oil, from castor beans
• Grape seed oil
• Hazelnut oil
• Hemp seed oil, from the Hemp - cannabis plant
• Linseed oil, from flax seeds
• Mustard oil, from the mustard plant
• Neem oil, from the neem tree
• Pumpkin seed oil
• Rice bran oil, from rice grains
• Walnut oil

Oil Extraction & Production from Oilseeds

Oilseeds processing & oil extraction comprise the following processes:

1. Storage of oilseeds
   1. Protection of Farm-stored Grains, Oilseeds & Pulses (PDF)
2. Cleaning of the oilseeds
3. Removing the husk or seed coating and separating the seeds from the chaff
4. Heating the seed

1. Equipment to Heat Oilseeds – from FAO
4. Extracting oil with an oil press, expeller or mortal & pestle

1. Principles of Oil Extraction – from ITDG (PDF)
2. Extraction of Oil from Oilseeds by Accelerated Solvent Extraction (PDF)
3. Kinetics & Thermodynamics of Oil Extraction from Sunflower Seeds in the Presence of Acidic Aqueous Hexane Solutions (PDF)
4. Small-scale Oil Extraction from Groundnuts & Copra
5. Extracted oil purification
6. Storing the purified oil

1. The Food Storage FAQ – Fats & Oils
2. Storing Fats & Oils

Lipids

Lipids in everyday terminology refer to fats and fat-like substances, and include sterols, fatty acids and related substances.

Lipids are a class of hydrocarbon-containing organic compounds essential for the structure and function of living cells. Lipids are characterized by being water-insoluble and soluble in nonpolar organic solvents such as ether. Lipids are usually aliphatic but they can have rings in their structure.

Although the word lipid is commonly used as a synonym to fat, fats belong to a subgroup of triglyceride lipids.

Most fixed oils from oilseeds contain lipids, usually in the form of triglycerides. Lipids may be accumulated in oilseeds in one or both types of seed tissue – the embryo or the endosperm. In oilseeds such as sunflower, linseed or rapeseed, it is accumulated in the cotyledons of the embryo. In species such as castor bean, coriander or carrot, the endosperm is the main site of lipid accumulation. An example of a plant in which lipids occur both in the embryo & the endosperm is tobacco (this definition is courtesy Plant Oils & Fats Page of Cyberlipid.org).

· Fatty Acids – from SV Lele

· CSIC – Spanish Institute of Fats & Oils

· Cyberlipid Center (see also: Plant Oils & Fats – from Cyber Lipid)

· DGF – German Society for Fat Science

· EFL: European Federation for the Science and Technology of Lipids (Euro Fed Lipid)

· Euro Fed Lipid (In German)

· Chilean Corporation of Oils and Fats (CORCHIGA)

· Ban Trans Fats

· Links to Fatty Places

· Netherlands Oils, Fats & Oilseeds Trade Association

· Euro Lipids – International Trade Fair for Fats & Oils & Related Technologies

· Japan Oil Chemists Society

· ISSFAL: International Society for the Study of Fatty Acids and Lipids

· Lipid Bank for Web Database, Japan

· Lipidforum - Nordic Forum for Lipid Research and Technology

· Lipids Analysis Unit, part of Scottish Crop Research Institute

· Lipid Technology & Enzymology

· The American Oil Chemists Society

· Plant Oils & Fats – Cyberlipid.org

· Lipids, Fats & Oils – Opportunities & Responsibilities in the New Century (PDF)

Essential Oils

Essential oils refer to the subtle, aromatic and volatile liquids extracted from the flowers, seeds, leaves, stems, bark and roots of herbs, bushes, shrubs and trees through distillation.

Essential oils are quite different from oils produced from oilseeds – that is soybeans, sunflower etc. The oil from the oilseeds traditionally comprise fatty acids, and these are very different in their chemical composition from the essential oils.

As against oilseeds bearing plants whose oils are present in the seeds, most essential oils occur in one or more of the following regions in a plant - cavities or ducts just below the epidermis (outer skin), and (b) glands or hairs originating from epidermal cells.

Essential oils are concentrated liquids containing volatile aromatic compounds. These oils are produced by distillation, expression, or solvent extraction. Essential oils are used in perfumery, aromatherapy, cosmetics, incense, medicine, household cleaning products, and for flavoring food and drink, and their use in aromatherapy and other health care areas is growing

Essential oils are responsible for the aroma and flavor associated with herbs, spices, and perfumes. Also called volatile oils because they easily diffuse into the air where they are then detectable by our olfactory senses, essential oils are usually terpenoids, another large class of “secondary” chemicals. Terpenoids are usually produced and secreted by specialized gland cells which may be present in virtually all plant parts i.e. leaves, stems, etc. Their presence in certain plant parts probably reflects their function. In addition to terpenoids, phenolic compounds are responsible for the aroma and flavor of some spices. For example, eugenol is a phenolic compound found in both cinnamon (Cinnamomum spp.) and cloves from Syzygium aromaticum.

The function of essential oils is debated. As with many secondary compounds, essential oils were once considered waste products. However, the biosynthetic pathways that yield essential oils are specialized and imply an expenditure of energy by the plant for their production. Another debated role for essential oils is to inhibit competing plants, or allelopathy. For example, essential oils in shed leaves can leach into the soil where they may inhibit the germination or growth of other plants competing for the same resources (e.g. light, mineral nutrients, water). As with many other secondary compounds, they are now believed to also deter herbivory and prevent infection by pathogens (i.e. bacteria and fungi). However, there is much to be learned about the physiological and ecological functions of essential oils whose functions probably also include the promotion of fire in fire-adapted species, attraction of pollinating and seed dispersing insects and vertebrates, and protection from oxidative stress caused by exposure to solar radiation (i.e. sunlight).e.g. a-pinene

What is the role of essential oils in plants? Put another way, why are these oils present in plants? Some of the reasons could be: (a) for attracting the pollinating insects by their aromas, and (b) for protecting against harmful organisms (insects and animals) by the anesthetic effects of the oils.

Links for Essential Oils

• Introduction to Essential Oils
• Essential Oils of India
• The Journal of Essential Oil Research
• Essential Oil Research Report, Weber University
• Essential Oils – How they Heal – form Wellness Directory of Minnesota
• Essential Oils & Plant Extracts Research Program – Govt. of Australia
• Essential Oil Supplier Guide & Directory - Oilganic
• Reference Guide for Essential Oils – from Dreaming Earth
• Essential Oils Reference Papers from Gritman
• Essential Oils Reference from Highlands Herbal
• Essential Oil Dictionary & Reference from Dean Coleman
• Essential Oils Reference Guide & Dictionary from Jordanian Society of Cosmetic Sciences
• Essential Oil Profiles from Aroma Web
• Castor Oil Dictionary
• Guide to Essential Oils – Magic Hands E-book Guide
• A Guide to Essential Oils – from Muti Oils
• Essential Oils – A Beginner’s Guide, from Holistic Shop, UK
• Essential Oils User Guide from Halz Herb
• R&D Plans for Essential Oils & Plant Extracts – Rural Industries Research & Development Corp, Australia
• Essential Oil Info & Resources
• A Resource on Essential Oils from Experience Festival
• FAQs on Essential Oils – from Kreative Living Koncepts
• Essential Oils & Their Production – from Crops & Food Research, Christchurch, New Zealand (PDF)
• Essential Oils & Plant Extracts Research Programme from Government of Australia
• Properties & Uses of Natural Essential Oils – from Menthol India
• Essential Oils from Washington State University
• Essential Oils from Wikipedia
• R&D Plan for Essential Oils & Plant Extracts – Government of Australia
• A List of Popular Essential Oils
• Seven Important Oils – from Cyberlipid
• Aromatherapy Essential Oils Properties & Latin Names
• Essential Oils & Absolutes Specification Chart
• How Do I Determine the Quality of Essential Oils? – University of Minnesota
• 100 Essential Oils of African Origin
• Horticultural Research in India
• Aromatherapy Carrier Oils
• Essential Oils & Fragrances from Natural Sources (PDF)

Essential Oil Extraction

The methods of extracting essential oils are:

Distillation

A majority of essential oils are extracted by distillation. The various distillation methods used are: Steam distillation, Hydro-distillation, water & steam distillation ( see also: Methods of Extracting Essential Oils)

· Essential Oil Distillation Methods

· Extraction of the Essential Oil of Lavender

· Essential Oil Steam Distillation Kit – from Heart Magic

· Essential Oil Distillation Equipment – MIT University (PDF)

· Distillation of Essential Oils – EssentialOils.co.za

· Home Distillation of Lavandin

Cold Pressing

Cold pressing method involves the simple pressing of the rind at about 120 degrees F to extract the oil. Little, if any, alteration from the oil's original state occurs – these oils retain their bright, fresh, uplifting aromas like that of smelling a wonderfully ripe fruit.

· How are Essential Oils Made – Dean Coleman

· Essential Oil Production

High Pressure CO2 Extraction

Both Carbon Dioxide and Supercritical Carbon Dioxide extraction involve the use of carbon dioxide as the 'solvent' which carries the essential oil away from the raw plant material.

The lower pressure CO2 extraction involves chilling carbon dioxide to between 35 and 55 degrees F, and pumping it through the plant material at about 1000 psi. The CO2 in this condition is condensed to a liquid.

Supercritical CO2 extraction (SCO2) involves carbon dioxide heated to 87 degrees F and pumped through the plant material at around 8,000 psi – under these conditions, the carbon dioxide is likened to a 'dense fog' or vapor. With release of the pressure in either process, the carbon dioxide escapes in its gaseous form, leaving the essential oil behind.
These CO2 methods have some advantages: Similar to steam distillation, there are no solvent residues left behind, and the resultant product is quite pure. Like solvent extraction, there is no heat applied to the plant material or essential oil to alter it in any way. The oil produced is very accurate with respect to the original state of the plant. The CO2 methods also are the most efficient, producing the most oil per amount of plant. The efficiency of CO2 extraction is particularly important when rare or endangered plant species are involved, such as Indian Sandalwood, since less of the precious plant is needed to produce an equivalent amount of oil.

· Super-critical Fluid Extraction

· Supercritical Fluid Extraction

Solvent Extraction

· Supercritical Fluid & High-pressure Solvent Extraction

· Hydrocarbon Solvents Used in the Extraction of Essential Oils

Maceration

· Maceration Extraction

Summary of Extraction Methods

High-pressure CO2 Extraction, while having some obvious advantages, is not always the best choice for a particular need, because they are the most expensive.

The resultant product differs slightly compared to one produced another way – the oils produced by steam distillation of some plants may sometimes be found to have a more agreeable aroma. Some oils, for example, seem to benefit from the steam distillation process by becoming a little warmer and richer. Other essential oils are produced quite effectively via steam distillation, with little alteration from the original plant state.

More Essential Oils Extraction Links

· Oilseeds Processing Resources from Michigan Tech

· Methods of Extracting Essential Oils

· Small-scale Production of Essential Oils (PDF)

· Essential Oils & their Production – NZ Institute for Crops & Food (PDF)

· Extraction Methods of Essential Oils & Resins – from Plant Resins

· CETIOM – Technical Center for Oilseed Crops, France

· Edible & Essence Oils Extraction References – Washington State University

· Small-scale Oilseed Processing – from Green Trust (PDF)

· The Sunflower Seed Huller & Oil Press – from Journerytoforever

· Small-scale Oilseed Processing – ATTRA (PDF)

· Oil Extraction Methods – from KVIC, India

· Example of a Complete Oil Mill – from Folkecenter, Denmark

· Edible & Essential Oil Processing

· Essential Oils – Methods of Extraction

· Microwave Extraction of Essential Oils – A Thesis Paper (PDF)

· Dictionary of Occupational Terms – Animal & Vegetable Oils, Fats & Grease Industry