Plant Oils and Types of Fats

Plant Oils: Fats, Soaps, and Waxes

• Plant oils are lipid-soluble triglycerides composed of three fatty acids and glycerol.
• Oils are liquid at room temperature, while fats are solid.
• Oils are typically extracted from seeds or, less frequently, from fruits.
• Edible oils include olive, soybean, sunflower, and safflower.
• Coconut and palm oils are commonly used in processed foods and cosmetics.
• "Drying oils" (e.g., cottonseed, linseed) are highly unsaturated and used in paints, varnishes, and lubricants.
• Plant oils are used increasingly to produce biodiesel fuel.

Types of Fats

• Saturated fats: No double bonds between carbon atoms in the fatty acid chain; fully saturated with hydrogen.
• Unsaturated fats: One or more double bonds in the fatty acid chain; not saturated with hydrogen.
  • Monounsaturated: One double bond.
  • Polyunsaturated: Multiple double bonds. (Omega-3 and Omega-6 are important examples).
• Hydrogenation: Adding hydrogen to an unsaturated fatty acid to create a saturated fatty acid; increases stability and melting point but produces trans fats.
• Cis double bonds: Hydrogen atoms are on the same side of the double bond; creates a bent structure.
• Trans double bonds: Hydrogen atoms are on opposite sides of the double bond; creates a linear structure; more stable and often higher melting point. Trans fats are not naturally found in plant oils.

Soap

• Soap is a salt of a fatty acid, formed when a fatty acid reacts with a strong base (saponification).
• Plant or animal oils are used to produce soap.
• The triglycerides are broken down into salts and glycerol.
• Soap molecules have a hydrophobic fatty acid end and a hydrophilic salt end, enabling them to emulsify and remove grease and dirt.
• Historically, soaps were made by hydrolyzing oils with lye, separating glycerol from the crude soap.
• Early soap-making records date to around 4,000 years ago in Babylon.
• Commercial soaps and shampoos often use detergents, such as sodium laureth sulfate (SLES) and sodium lauryl sulfate (SLS).

Biodiesel Fuel

• Biodiesel fuel is made from methyl esters, produced by transesterification using alcohol (typically ethanol or methanol) to replace glycerol in the fatty acid chain.
• Biodiesel has lower lifecycle emissions than petroleum-based diesel.
• Biodiesel's energy balance can vary based on the plant source.
• Plants like palm oil and algae have high production efficiency.
• Biodiesel may have higher nitric oxide emissions.

Major Plant Oils (Cool Temperate Climates)

• Canola (Brassica napus): A versatile crop (canola oil, rutabaga, kale); high in healthy oils (omega-3 and -6); rich in polyunsaturated fatty acids.
• Sunflower (Helianthus annuus): Drought-tolerant, originating from North America; now developed with high oil content.
• Linseed/Flax (Linum usitatissimum): High in omega-3 and -6 fatty acids, vitamin E, and protein; used for edible and industrial oils.
• Olive (Olea europaea): Native to the Mediterranean, long-lived, high quality oils extracted from the fruit. Virgin olive oil is cold-pressed. High in monounsaturated fats like oleic acid.
• Sesame (Sesamum indicum): Ancient cultigen, high in unsaturated fats, protein, iron, and calcium; used in Middle Eastern and Asian cooking.
• Peanut (Arachis hypogaea): Cultivated in South America for millennia; high in unsaturated oils, protein, and vitamins; used in cooking and processed foods.
• Cottonseed (Gossypium hirsutum): By-product of the cotton industry; refined oil used in foods; high in vitamin E.
• Corn/Maize (Zea mays): Large annual grass from Central America; high polyunsaturated oil (linoleic acid).
• Soybean (Glycine max): Originated in East Asia; high in protein and edible oils; widely used in Asian cuisine.
• Safflower (Carthamus tinctorius): Initially used for dye; now a major oil crop, high in linoleic acid.