Plant Oils: Fats, Soaps and Waxes (Biol 1300 Unit 9) PDF

**Biol 1300 Unit 9** **PLANT OILS: FATS, SOAPS AND WAXES** **WHAT ARE PLANT OILS?** Plant oils are lipid-soluble triglycerides (molecules) consisting of three fatty acids and glycerol. Examples include oil and fat, with oils being liquid at room temperature and fats being sol...

**Biol 1300 Unit 9** **PLANT OILS: FATS, SOAPS AND WAXES** **WHAT ARE PLANT OILS?** Plant oils are lipid-soluble triglycerides (molecules) consisting of three fatty acids and glycerol. Examples include oil and fat, with oils being liquid at room temperature and fats being solid. Plant oils are typically extracted from seeds or, less commonly, from fleshy fruits. Edible oils include olive, soybean, sunflower, and safflower oils. Coconut and palm oils are widely used in processed foods and cosmetics like shampoos, soaps and creams. Highly unsaturated plant oils (known as \"drying oils\"), such as those from cotton, soybean, castor bean, sunflower, safflower, linseed and the tung tree, are used in lubricants, paints, and varnishes. With rising petroleum prices, plant oils are increasingly used to produce biodiesel fuel. Plant oils can be: - **Saturated fats:** have *no double bonds* between the carbon atoms in the fatty acid chain, meaning they are "saturated" with hydrogen atoms. - **Unsaturated fats** have *one or more double bonds* in the fatty acid chain, meaning not all carbon atoms are fully bonded with hydrogen atoms. Monounsaturated oils have *one* double bond, while polyunsaturated oils have *multiple*. **Hydrogenation**, which heats oil in a vacuum with water, saturates an unsaturated fatty acid chain to prevent oxidation (oxidation makes oils rancid) so it lasts longer and increase viscosity and melting point (e.g. to turn a liquid oil into a solid fat). However, this process creates trans fatty acids, which raise "bad" LDL cholesterol (low-density lipoproteins) and lower "good" HDL cholesterol (high-density lipoproteins), increasing heart disease risk. The term **trans** refers to the configuration of the hydrogen atoms along the carbon chain of the fatty acid: - **Cis double bonds**: The hydrogen atoms are on the same side of the double bond.  - **Trans double bonds**: The hydrogen atoms are on opposite sides of the double bond. [This configuration results in a more linear structure, making the molecule more stable and often giving it a higher melting point compared to its cis counterpart](https://chemistrytalk.org/cis-trans-isomers/). Trans fats are more stable and extend shelf life but are not naturally present in plant oils (rather the cis arrangement is natural), only in small amounts in ruminant meat and milk. Therefore, the trans isomer is bad for human health but is present in many processed foods. *Unsaturated* plant oils, especially omega-3 fatty acids, are crucial for human health. They are essential for normal child development and may reduce the risk of heart disease. Additionally, they can help alleviate depression and anxiety and prevent the buildup of abnormal proteins (beta amyloid and tau) that contribute to memory and cognitive decline in later life. **SOAP** Soap, a salt of a fatty acid when it reacts with a strong base (chemically, a salt is the result of an acid and base reacting), is made from plant or animal oils through saponification. This reaction replaces the triglycerides with salt, breaking down the fatty acids and the glycerol. Historically, soaps were sodium or potassium salts of fatty acids, created by hydrolyzing oils with lye to separate glycerol from crude soap. Soap molecules have a hydrophobic (water-insoluble) fatty acid end and a hydrophilic (water-soluble) salt end. The fatty acid end readily dissolves non-polar substances like grease and dirt and the hydrophilic end washes these away with water as a result (non-polar substances in general are hydrophobic, drawing them to other hydrophobic substances and polar substances are hydrophilic). The earliest records of soap date back to Babylonian clay tablets around [4,000 years ago], describing a bathing rinse made from water, alkali, and cassia oil. Ancient Egyptians also made soap-like substances for cleansing and medicinal purposes, mentioning it in an important ancient medical document *Ebers Papyrus*. About [2,000 years ago], Ancient Romans created a hair pomade by mixing tallow (animal fat) with wood ash. Medieval Muslims produced the first modern soaps about [1,400 years] ago through saponification of olive oil with thyme as a perfume. In Medieval Europe, soaps were mainly made from animal fat (tallow) and wood (soda) ash. [In the 1500s], Spain and Italy developed castile soaps from plant oils, using olive oil and barilla lye. When burned, their ashes produce a lye solution rich in sodium carbonate, which was used in traditional soap making. Soap can be made from various plant oils, with olive oil producing mild soap, coconut oil creating soft, heavy-lathering soap, and palm oil making hard soap. Today, many commercial soaps and shampoos are detergents like sodium laureth sulfate (SLES) and sodium lauryl sulfate (SLS), which are less expensive and easier to manufacture. Recently, there has been a resurgence in natural soaps made from plant oils, such as sodium cocoate (from coconut oil), sodium peanutate (from peanut oil), \"saponified olive oil\", etc. **BIODIESEL FUEL** Plant oils can be used to produce biodiesel fuel, which consists of methyl esters, unlike petroleum-based diesel that contains 75% saturated and 25% aromatic hydrocarbons (primarily naphthalene and alkylbenzene). Biodiesel is made through transesterification, using alcohol (usually ethanol or methanol) to separate fatty acids from glycerol and replace the glycerol with alcohol. It produces about 60% less net life cycle emissions compared to petrodiesel. In Germany (a major fuel user), the energy balance of biodiesel is 2.5, meaning one unit of fossil fuel input produces 2.5 units of biodiesel. It is also a renewable energy source as the carbon dioxide produced is fixed by plants. However, biodiesel has about 10% higher nitric oxide emissions (a significant air pollutant) and viscosity issues in cold weather (biodiesel produced from canola oils gels at temperatures below -10⁰C). Production efficiency varies by species, 150 kg/ha for corn oil, 800-900 for peanut and sunflower oil, 1,000 for canola oil, and exceeding 5,000 for palm oil and algae may potentially yield over 7,000 kg/ha. A mnemonic to memorize these can be **C**lever **P**eople **S**ave **C**rops **P**roperly **A**lways. **MAJOR PLANT OILS: COOL TEMPERATE CLIMATES** **CANOLA** (*Brassica napus* var. *napus* and var. *oleifera*) Canola (Brassica napus var. napus and var. oleifera) is a versatile species that includes canola (for edible oil), rutabaga (for edible taproots), and kale (for edible leaves). It is an annual species of European origin, a hybrid of turnip and cabbage. The variety **canola** (from \"**Can**adian **o**il, **l**ow **a**cid\"), developed in the 1970s at the University of Manitoba. Canola is productive, well-suited to the prairie climate, low in erucic acid, and high in healthy oils like omega 3 and 6. Canola seeds contain 40% oil, rich in polyunsaturates like oleic and linoleic acid. Canola oil is widely used in cooking, salad oils, margarines, and mayonnaise, and has potential as a biodiesel source. It is a significant commercial crop in Canada and Europe, with millions of hectares cultivated annually. **SUNFLOWER (Helianthus annuus)** The sunflower, a drought-tolerant annual native to the western United States, is one of the few common agricultural crops originating from North America, first domesticated around 2,000 years ago. In the 1950s, Soviet scientists developed sunflower varieties with over 50% oil in the seeds. Recently, dwarf varieties have been created to optimize mechanical harvesting. Sunflower oil is important for use in salad and cooking oils, margarines, and various processed foods. **LINSEED or FLAX (Linum usitatissimum)** Flax is a small annual plant native to the Mediterranean, domesticated over 8,000 years ago for its plant fiber in Mesopotamia, which is still used to make linen. Cultivars with larger seeds have been developed, used for edible and industrial oils. *Edible* flax seed oil, high in omega-3 and omega-6 fatty acids (linoleic and linolenic acids), vitamin E, and protein, is extracted by *cold pressing* seeds and is a common cooking oil in North Africa and the Middle East. The high mucilage content aids digestion and acts as a mild laxative. *Hot-pressed* *industrial* flax seed produces linseed oil, used in paints, varnishes, and as a wood finisher. **MAJOR PLANT OILS: WARM TEMPERATE CLIMATES** **OLIVE (Olea europaea)** The olive tree, native to the Mediterranean and western Asia, is long-lived but cannot tolerate prolonged freezing. It has been used by ancient civilizations like the Assyrians, Egyptians, Greeks, Romans, and Palestinians. Olive leaves and branches symbolize peace and goodwill. While traditionally grown in the Mediterranean, increased demand has led to commercial plantations in Africa, Australia, South America, and California. Olive oil is extracted from the fruit pulp of olives, not the seed. Olives can be eaten whole, with green olives coming from unripe fruit and black olives from ripe fruit. The bitter olive fruit must be processed to be edible: unripe olives are treated with lye and pickled in brine, while ripe olives are simply pickled. Over 90% of harvested olives are used for oil extraction. The fruit pulp is high in oil (about 40%), mainly consisting of beneficial monounsaturated fats like oleic acid (about 75%) with lesser amounts of palmitic and linoleic acids. Olives are also rich in calcium, potassium, and vitamins. The best quality olive oil, "virgin" oil, is obtained by cold pressing the fruit, with "extra virgin" oil coming from the first pressing of the best olives. Traditionally, virgin oil was extracted using a heavy stone wheel. Virgin olive oil retains a distinct olive flavor and aroma and is prized for cooking and salads. Cheaper refined olive oil, produced by hydraulic pressing and solvent extraction, has its smell and flavor removed and is used in prepared foods and soap production. **SESAME** (Sesamum indicum) Sesame is an annual species producing oblong capsule fruits that contain small, oval seeds rich in unsaturated fats. Sesame is an ancient cultigen that was first domesticated in India or East Africa. Sesame oil is mentioned in ancient Assyrian clay tablets and was known to the Ancient Greeks. The seeds can be eaten raw or roasted and are processed in several ways. Sesame oils and sauces are especially popular in Japan, China, Africa and the Middle East. Halva is a mixture of ground sesame seeds, almonds and sugar. Lebanese tahini is a thick paste of ground sesame seed, lemon juice, pepper, garlic and other spices; hummus is tahini mixed with pureed chickpeas. The seeds, which can be stored for long periods without becoming rancid, are high in unsaturated fats, protein, iron and calcium. **PEANUT** (Arachis hypogaea) The peanut, a member of the Pea (Fabaceae) Family, is native to South America and has been cultivated there for at least 3,500 years. It is an annual plant that produces self-pollinating yellow flowers, with the flower stalk elongating after pollination to push the developing seedpod into the ground. The mature fruit is a soft-shelled legume containing two seeds rich in unsaturated oils, mainly oleic and linoleic acids. Both prostrate and upright forms are grown, and many varieties exist. Peanuts are now widely cultivated in Africa, India, China, Southeast Asia, and the United States, with annual production exceeding 30 million tons. Peanut oil is commonly used in cooking, salad dressings, margarines, and other processed foods, as well as in soap manufacturing. Roasted peanuts are eaten whole or processed into pastes like peanut butter and peanut sauce. Peanuts are rich in unsaturated oil (about 50%), protein, and vitamins. **COTTONSEED** (Gossypium hirsutum) Cottonseed oil, a by-product of the cotton textile industry, has recently become an important source of edible oil. It is extracted from seeds using solvent extraction after the seed hairs (which are used for cotton fabric) are removed through ginning. Crude cotton oil is dark brown and requires refinement to be suitable for consumption. The refined oil is used in prepared foods like margarine and cooking fats but is not ideal for cooking as it solidifies at room temperature. Cottonseed oil is relatively rich in polyunsaturated oils (20-30%) and high in vitamin E. **CORN or MAIZE** (Zea mays) Corn, a large annual monocot grass (family Poaceae) with a complex hybrid origin, is likely derived from wild teosinte native to Central America and has been cultivated for at least 7,500 years. Today, it is grown worldwide, with major producers including the United States, Central America, and Africa. In the U.S., most corn is used for cattle feed and biofuel, while in Central America and Africa, it is grown for human consumption, either whole or as baked flour (tortillas). Corn seeds, which are about 50% oil, can be processed to produce corn oil. This oil is mostly polyunsaturated (about 60% linoleic acid) and is used as a cooking oil and in various prepared foods. **SOYBEAN** (Glycine max) The soybean, a member of the Pea (Leguminosae or Fabaceae) Family, is a cultigen of uncertain origin but likely originated from wild soya in China, Japan, and Korea. Domesticated around 3,000 or earlier years ago in northeast China, it is now a major economic crop with over 100 million tons produced annually. The main producers are the United States, Brazil, Argentina, and China. Soybeans are high in protein (30-40%) and edible oils (12-24%). They are used in various Asian foods like pastes (miso), sauces (shoyu), curd (tofu), fermented cakes, soy flour, and germinated seedlings (bean sprouts). The fresh and dried beans are also used in cooking. Processed soy protein is used to produce textured vegetarian products, such as milk and meat substitutes. Soy oil, rich in unsaturated fats (mainly linoleic and oleic acids), is used as a salad and cooking oil, and as an ingredient in mayonnaise, margarine and other processed foods. **SAFFLOWER** (Carthamus tinctorius) Safflower, a member of the Sunflower Family, a cultigen of uncertain origin, was first domesticated in the Middle East and later spread to India, Africa, Europe, and China. Initially grown for its dye (the dried flowers produce a colorfast yellow-orange dye), safflower became an important seed oil crop in the 20th century. It is like saffron but cheaper. Major producers include India, the United States, Mexico, Argentina, and Spain. Safflower tolerates drought and salinity, making it suitable for marginal land. The oil is extracted from the seeds by cold-pressing or solvent extraction. The refined oil, high in linoleic acid, about 75%, the highest percentage of polyunsaturates for edible seed oils. One variety consists of mainly monounsaturates, is used in cooking, salad oils, and soft margarines. Another variety consists of polyunsaturates, used in light-colored oil-based paints, having the advantage of not yellowing with age. The seeds are also high in protein and the remaining seedcake is used as livestock feed after oil extraction as a protein source. **MAJOR PLANT OILS: TROPICAL CLIMATES** **OIL PALM (Elaeis guineensis)** The oil palm is a large, single-stemmed monocot palm native to tropical West Africa. It has separate clusters of male and female flowers on the same plant, with each female cluster producing several hundred fruits (2-6 flower clusters per plant). The fruit has a thin outer skin (exocarp), a fibrous, oil-rich mesocarp, and a black endocarp shell containing an oil-rich seed. Both the mesocarp and seed contain about 50% oil. The high-yielding tenera variety is the most widely planted, capable of producing over 6.5 tons of oil per hectare under optimal conditions. The oil is cold extracted using mechanical presses, producing two types of oil: - **Palm oil**: Yellow, from the mesocarp, with equal proportions of saturated and unsaturated oils. - **Palm kernel oil**: Orange red, from the seed endosperm, 100% saturated, with a distinct aroma of violets. Palm oil is used in margarines, snack foods, soaps, candies, and as a cooking oil. Palm kernel oil is used in candy, confections, ice cream, and as a cocoa butter substitute. Both oils are high in saturated fats, so moderate consumption is key. Oil palm is the second most important source of plant oils, after soybeans. Large plantations have been established in west Africa, Southeast Asia (particularly Malaysia and Indonesia) and Brazil (South America) to meet global demand. Large tracts of tropical rainforest have been converted to high-intensity oil palm monoculture production, compromising biodiversity and destroying natural habitat. **COCONUT** (Cocos nucifera) The coconut is a large monocot palm species native to Malaysia (islands between Southeast Asia and the western Pacific) and spread by Polynesians throughout the Indian and Pacific Ocean regions about 3,000 years ago. Today, coconuts are found throughout the tropics. The plant bears male and female flowers in separate clusters. The large fruit has a fibrous waterproof pericarp surrounding a large seed, which contains white fleshy endosperm (coconut meat or copra) and liquid endosperm (coconut water or milk). Coconut oil is extracted from dried copra by cold pressing and is used in confections, ice cream, and margarines. It is high in saturated fats thus moderation is encouraged. Over 40 billion coconuts are harvested annually, with major producers being Indonesia, the Philippines, India, and Sri Lanka. Coconut harvesting and processing are very labor-intensive. **TUNG** (Vernicia fordii) The tung tree, native to Southeast Asia (China, Burma, and Vietnam), produces seeds from which tung oil is extracted. Historically, tung oil was used in lamps for light and heat in Ancient China. Today, it is valued for its high-quality drying properties, used in pure form or mixed into paints and varnishes. Tung oil, mainly composed of highly unsaturated eleostearic acid (three double bonds), giving tung oil its drying properties (like linseed oil) but is preferred by woodworkers over the latter for its tough, water-resistant finish that does not darken with age. **WAXES** Plant waxes are complex lipids made of long-chained alcohols (longer than glycerol, the alcohol of plant oils) plus numerous fatty acids (more than the three present in plant oils). They form a protective coating on leaves (the waxy cuticle layer) and some fruits, like apples. While most plants produce small amounts of wax, a few species generate thick wax deposits that can be harvested. Nowadays, many commercial "waxes" are synthetic, petroleum-based products. **CARNAUBA** (Copernicia prunifera) Carnauba wax, derived from a monocot fan palm native to Brazil, forms a thick waxy cuticle on the leaves. About 50 leaves are needed to produce one kilogram of wax. The leaves are harvested, shredded, and dried, causing the wax to flake off. The flakes are then melted, strained, and molded into blocks. This high-quality, hard wax is used in car and furniture polishes, dental floss, waterproofing disposable cups and plates, lipsticks, and creating a shiny surface on candies. **JOJOBA** (Simmondsia chinensis) Jojoba is an evergreen shrub native to the deserts of northwest Mexico and the adjacent United States. The species has separate male and female plants. The female plants produce seeds rich in liquid wax, often called "jojoba oil," which remains liquid at room temperature due to unsaturated fatty acids. A solid wax is produced by hydrogenation. Historically used by Sonoran Indians for hair care, jojoba wax is now used in cosmetics, beauty aids (e.g. shampoos and hair conditioners), and as an automobile lubricant. Jojoba plantations were established in the 1980s in the deserts of the United States and Israel to meet commercial demand. **CANDELILLA** (Euphorbia antisyphilitica) Candelilla wax is derived from a leafless shrub found in the deserts of northern Mexico and the southwestern United States. Despite the absence of plantations, its production from natural populations is a significant cottage industry in northern Mexico. The wax is extracted by boiling the plant material in dilute acid. It is primarily used in the cosmetics industry, like jojoba, and also serves as a substitute for carnauba wax and as a binding agent in chewing gum.