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Fatty Oils & Waxes
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The terminology used here to describe the various kinds of oils and waxes
reflects their physical rather than chemical characteristics
Fatty oils are fixed oils because they do not evaporate or become volatile. They cannot be distilled without being decomposed. Chemically fatty oils are close to animal fats. They contain glycerin in combination with a fatty acid. They are liquid at room temperature and usually contain oleic acid. However, fats are solid at room temperature and contain palmitic or stearic acid. Fatty oils are insoluble in water but soluble in several organic solvents. Breakdown products of fats are fatty acids and glycerin accompanied by a rancid odor and taste. Boiling a fat with an alkali causes it to decompose and the fatty acid unites with the alkali to form soap. The addition of lye or potash will make the soap softer, if soda is used a hard soap results.
Fatty oils occur in many plant families, both tropical and temperate. They are stored, frequently in large amounts, in seeds and somewhat in fruits, tubers, stems and other plant organs. They may also contain proteins. This kind of reserve food material is available as a source of energy for the processes involved in seed germination. Fatty oils are bland and lack the strong taste, odor and antiseptic qualities of essential oils. Thus they are suitable for human food. These edible oils contain both solid and liquid fats and form an important part of the human diet.
Extraction of fatty oils varies. Usually the seed coats have to be removed and then the remainder is reduced to a fine meal. The oils are removed by solvents or by subjecting the meal to hydraulic pressure. The residue is rich in proteins and is valuable as an animal food and fertilizer. Pressure causes the cell walls to break and the fats are released. The extracted oils are filtered and may be further purified. Higher grades are edible and lower grades are used in various industries. Fatty oils may also have medicinal value.
Four classes of plant fatty oils are (1) drying oils, (2) semidrying oils, (3) nondrying oils, and (4) fats or tallows. The drying oils can absorb oxygen and on exposure dry into thin elastic films. These oils are importance in the paint and varnish industries. Semidrying oils absorb oxygen slowly and only in small amounts. They form a soft film only after long exposure to air. Some are edible; others are used as illuminants or in making soap and candles. The nondrying oils remain liquid at room temperature and do not form a film. Such oils are edible and may be used for soap and lubricants. The fats are solid or semisolid at room temperature. They are edible and also useful in the manufacture of soap and candles. Drying and semidrying oils are more common in plants of temperate climates, while nondrying oils and fats predominate in plants of tropical areas.
Flax seed, Linum usitatissimum, has been the source of one of the most important of the drying oils. The oil content is 32-43 percent. The seeds are collected and stored for several months. Then impurities are removed and the seeds are ground to a fine meal. The oil is usually extracted by pressure with heat or by the use of solvents. Cold-pressed oil is produced in Eastern Europe where it is used for human consumption. Linseed oil varies from yellow to brownish in color and has an acrid taste and smell. It forms a tough elastic film when oxidized. Heating the raw oil to 125 deg. Centigrade increases this drying property. This produces the “boiled” linseed oil. Linseed oil has been used mainly in making paints, varnishes, linoleum, soft soap and printer’s ink. Following extraction, the oil cake can be used as an animal feed.
Argentina has been the main producer, where over six million acres were devoted to seed-flax cultivation by the mid 1900’s. Russia, India, China, Uruguay and Canada and the United States also produced considerably quantities. Montana, the Dakotas and Minnesota were the centers of seed-flax production in the United States, with an annual yield of 40 million bu. by 1950.
Tung oil, or Chinawood oil, has been widely used in the varnish industry and as a substitute for linseed oil. It is obtained from the seeds of two Chinese species of Aleurites, A. fordii, the tung-oil tree, a species native to central and western China, and A. montana, the mu tree, found in southwestern China. Oils from these trees are almost identical in composition and properties and imported tung oil is often a mixture of the two. In China tung oil has been used for centuries in waterproofing wood, paper and fabrics. It is a good preservative and is resistant to weathering, so it is especially valuable for painting outdoors. Boatmen have sought after tung oil because it is little affected by water.
In the United States cultivation of A. fordii began in 1905 and grew to 75,000 acres in the Gulf States by the mid 1950’s. Tung trees are handsome and are often planted as ornamentals. The tung oil industry had assumed great importance in southern agriculture by the mid 1950’s. Not only was it a profitable source of income, but also the orchards could be planted on otherwise useless eroded land.
The outer husk of the fruit is removed and the oil is expressed from the seeds by expeller presses. Tung oil is pale yellow to dark brown and dries very rapidly and also has preservative and waterproofing qualities. Consequently, its chief use has been in the varnish and paint industries, where it largely replaced kauri and other hard resins. Large quantities were also used in producing linoleum, oilcloth, brake linings, soap, leather dressings, inks, insulating compounds and fiberboard. The oil cake is a good fertilizer but is unsuitable as an animal feed.
Soybean, Glycine max, is native to China and has been a most important food plant in Eastern Asia. The oil is midway between linseed and cottonseed in its characteristics, so that sometimes it is classified as a drying oil or semidrying oil. The oil is extracted from the seeds by expression with hydraulic or expeller presses or by the use of solvents. The oil content of improved varieties now exceeds 22 percent. After refining, soybean oil can be used in salads or as cooking oil and for other food purposes. There ore many food products made from it, such as margarine, tofu, ice cream substitutes, vegetarian meat substitutes, etc. It is also used in the manufacture of soap, candles, varnishes, lacquers, paints, linoleum, greases, rubber substitutes, cleaning compounds disinfectants and insecticides. The oil cake or meal has a 40-48 percent protein content and is valuable as a meat substitute and feed for livestock. It is also used for adhesives, plastics, foaming solutions, spreaders, fertilizers, sizings, synthetic textiles, etc.
Seeds of large evergreen tree of northeast Brazil, Licania rigida, provide this oil. It has been used as a substitute for tung oil. It is extracted by solvents or by hydraulic presses. This oil finds use in the paint and varnish industries; in making linoleum, printing inks and brake bands; and for improving the elasticity of rubber. It has been used in Brazil as an illuminant and medicine.
The seeds of Perilla frutescens, an aromatic annual, 3-5 ft. in height with numerous branches, provides this oil. Native to northern India, China and Japan, it is extensively cultivated in the Orient, especially in Manchuria and Japan. The plant matures slowly and must be harvested before it is completely ripe or the seeds will fall from their capsules. The oil is expressed from roasted and crushed seeds and is edible, having been used for centuries. Industrial uses of perilla oil are much more important. It is deployed in the manufacture of Japanese oilpapers, cheap lacquer, paper umbrellas, waterproof clothes, printer’s ink and leather. A considerable amount of this oil was imported into North America during the mid 1950’s as a substitute for linseed oil.
The oil is from the hard-shelled seeds of Aleurites moluccana, native to Malaya and Pacific Islands. In the Philippines it is called lumbang oil. It is a good drying oil and has been used in making paints, varnishes, lacquer, linoleum and soft soap and as a preservative for the hulls of ships. The nuts were at one time used in Hawaii and other Polynesian islands for illumination, thus the name candlenut. The oil cake is poisonous and may be used only as a fertilizer.
The mature and old kernels of English walnut, Juglans regia, and yield a drying oil used for white paint, artist paints, printing ink and soap. Hot-pressed oil is adapted for these purposes. The fresh oil and cold-pressed oil have a pleasant odor and nutty flavor and are edible. Waste kernels from the shelling process may be used as a source of the oil.
This oil is pale yellow and comes from the seeds of Guizotia abyssinica, an annual plant in tropical Africa. It is cultivated in India, Africa, Germany and the West Indies. Higher grades have a pleasant aromatic odor and are used for food, while poorer grades are made into soak or serve as illuminants. There has never been a widespread use of this oil in the Western Hemisphere.
Seeds of the poppy, Papaver somniferum, provides an important drying oil. This drug plant is grown for its edible seeds in northern France and Germany and in India. The first pressing yields white edible oil, while a second hot pressing furnishes reddish oil used for lamps, soap and, after bleaching, for oil paints.
Safflower, Carthamus tinctorius, is the source as a dye as well as oil from its seeds. It is extensively cultivated in Egypt, India and the Orient and somewhat in North America. It is widely used in Mexico Uses include manufacture of paints, soap, varnishes, illuminant and edible oil.
This is really not true oil but a byproduct of the sulfate pulp industry. The waste liquor from pine pulp mills is concentrated by evaporation, and the soap curds are removed and acidified. Crude tall oil, which results, contains fatty acids, resins and other substances. It is refined by steam distillation. It is used in the manufacture of soap and, after treatment with glycerin, as a drying oil.
Drying oils may be obtained from many other plant species, some of which have commercial importance. Among them is hemp, Cannabis sativa, grown in China, Japan and Europe and the oil is extracted from seeds. It is used for soap, paints, varnishes and lamp oil. The seeds of tobacco, Nicotiana tabacum, Hevea brasiliensis, Manihot glazovii and other sources of rubber furnish oil as well as grapes and raisins. Grape-seed oil in particular has become popular in California as a food product.
The most important of the semidrying oils, cottonseed oil is used as the standard of comparison. The United States has been the main producer, but almost all the cotton-growing nations provide varying amounts. Over one billion pounds of the oil were expressed annually in the United States by the mid 1950’s. The industry was first established around 1880, prior to which cottonseeds were merely discarded. The seeds are carefully cleaned and freed from impurities and the linters and usually the hulls are removed. The kernels are then crushed and heated and are finally subjected to hydraulic pressure or expeller presses. The oil is pumped into tanks where impurities settle out. The pure refined oil is of value as a salad and cooking oil and for making margarine and lard substitutes. The residue is the source of various products that have a wide range of industrial uses. Among these are soap, oilcloth, washing powders, artificial leather, roofing tar, insulating materials, putty, glycerin and nitroglycerin. Cottonseed meal is important as a food for animals and as a fertilizer.
There is about 50 percent oil located in the embryo of maize kernels. It is used for a wide variety of purposes. Refined oil is for human consumption either directly or in margarines, while the crude oil has industrial uses such as the manufacture of rubber substitutes, paints, soaps. Corn oil has little lubricating value.
Also known as gingelly oil, sesame oil is the product of seeds of an annual herb, Sesamum indicum. It has been a chief oil of India and was cultivated there and in China from ancient times. Its use has spread to other tropical regions and it is now grown in many Asiatic, African and tropical American countries. China produces about one-half of the world supply, India one-third and Africa and America the rest. Slaves brought sesame oil to North America, and in the southern United States the plant was grown in slave days.
The seeds contain about 50 percent oil that is easily extracted by cold pressure. The finer grades are tasteless and nearly colorless and are used as a substitute for olive oil in cooking and in medicine. Enormous quantities of sesame oil are used in Europe in the manufacture of margarine and other foods. Poorer grades of oil are used for soap, perfumery and rubber substitutes and sometimes as a lubricant. In India the oil is used for anointing the body, as fuel for lamps and as food. Oil cake is a good cattle feed, and sesame seeds are also used in confectionery and baking industries.
Common sunflower seeds, Helianthus annuus, contain 32-45 percent of light golden-yellow oil equal to olive oil in its medicinal and food value. It is an excellent salad oil and is used in margarines and lard substitutes. The seeds are a nutritious bird and poultry food, while the oil cake is excellent for livestock and the whole plant is often grown for silage. The oil has semidrying properties rendering it useful in the varnish, paint and soap industries. Its origins probably lie in South America but it is cultivated worldwide. Rumania, Russia and Argentina are big producers of sunflower seeds, while increasing acreage is planted in North America.
Seeds of several species of Brassica, mainly B. campestris, B. napus (rape) and B. rapa, yield oils with characteristics that classify them as rape or colza oils. The oil content is 30-45 percent and expression or solvents extract the oil. Rapeseeds have been widely cultivated in Europe, China, Japan and India. The crude oil is edible when cold pressed and is used for greasing loaves of bread before baking. It is used in lamps, in oiling wooden goods, in the manufacture of soap and rubber substitutes and for quenching or tempering steel plates. The refined oil, or colza oil, is edible and it can be used as a lubricant for delicate machinery.
Other sources are camelina oil from Camelina sativa, which is grown in Europe for its seed and used for soap and as an illuminant; croton oil, a powerful drug that is treated under “Medicinal Plants;” and argemone oil from Argemone mexicana. The seeds of many varieties of cultivated plants, such as pears, apricots, apples, peaches, cherries, plums, citrus, cereals, tomatoes, canteloupes, watermelons, pumpkins and black and white mustard also contain semidrying oils.
The fruits of the olive, Olea europaea, provide olive oil, and it is the most important of the nondrying oils. The tree is a small evergreen cultivated principally in Mediterranean countries and to a lesser degree in South Africa, Australia, South America, Mexico and the United States. The world production of olive oil has exceeded two billion pounds since the mid 1950’s, with Spain, Italy, Greece and Portugal the leaders. Oils from the latter countries are believed superior in flavor to those from other areas.
The oil is squeezed from the pulp either by hand or mechanically. The finest grades are obtained by the former method. These oils are golden yellow, clear and limpid. They are used chiefly as salad and cooking oils, in canning sardines and in medicine. Inferior grades have a greenish tinge and are used for soap making and as lubricants. The poorest grades are obtained by the use of solvents after several pressings. Fully ripe olives give the largest yield. Olive oil is one of the most important food oils as it will store for long periods and becomes rancid only when exposed to the air. The oil cake is used for stock feed and as a substitute for humus in coil conditioning.
<bot477> Wild olive trees (Olea sp.), central Kenya
Seeds of the common peanut, Arachis hypogaea, originally from South America, provide peanut oil. The plant was widely used by Amerindians in Peru and so highly regarded that gold replicas are found in the tombs.
The main producers are China, India, Africa, and the United States. The seeds are shelled, cleaned and crushed, and both hydraulic presses and expellers express the oil. The filtered and refined oil is edible and used as a salad oil, for cooking, for packing sardines, in making margarine and shortenings, and as an adulterant for olive oil. Inferior grades are for soap making, lubricants, and illuminants. The oil cake is an excellent livestock feed as it has higher protein content than any other similar product. Peanut oil is in great demand in Europe where it is extracted with solvents as well as by expression. Spanish peanuts are grown in the United States for oil production because they have higher oil content.
Seeds of Ricinus communis furnish versatile oil. The plant is a coarse erect annual herb that is cultivated in both temperate and tropical regions. In North America it is a favored ornamental plant but has been grown for its oil. The characteristically marked seeds contain 35-55 percent of thick colorless or greenish oil that is obtained by expression or solvent extraction.
The chief use of castor oil used to be in medicine, where it acts as a purgative. Presently most of the production is utilized in industry in the manufacture of over 25 different products. It is water resistant and thus may be used for coating fabrics and for protective coverings for airplanes, insulation, food containers, firearms, etc. It is an excellent lubricant especially for airplane engines. When hydrated it is converted into a quick-drying oil used in paints and varnishes. Caster oil may also be used in making soap, inks and plastics, for preserving leather and as an illuminant. The leaves have insecticidal properties, while the stalks are a source of paper pulp and cellulose. The oil cake or pomace is poisonous but makes and excellent fertilizer.
Of minor importance are kapok oil from the seeds of the kapok tree and used as a substitute for cottonseed oil; tea-seed oil from Camelia sasanqua, a valuable oil in China, Japan and Assam; and oil of ben from Moringa oleifera. Nondrying oils are also obtained from almonds, pecans, filberts, pistachio, and pili nuts and from the flesh of avocados.
A widely used fatty oil, coconut oil is obtained from the dried white interior of the seed of Cocos nucifera. This oil is pail yellow or colorless and is solid below 74 deg. Fahrenheit. Following harvest, the nut husks are removed and the interior split open and dried either by natural or fire heat. The dried tissue, or copra, is then easily removed. This is ground up and the oil expressed. The cake is sometimes placed in a hydraulic press a second time, and still more oil is removed. The yield is 65-70 percent. Fresh coconut meat can be pressed also giving a yield of 80 percent or more oil. Refined coconut oil is edible and is now extensively used as a food product. It is especially well adapted for the purpose of margarines because it is solid at room temperature. It is used in candy industry and for making the highest quality soaps, cosmetics, salves shaving creams, shampoos, suntan lotions, etc. It is used for marine soaps and also as an illuminant. The cake is an excellent livestock feed. Copra is produced in Ceylon, India, Polynesia, the Philippines and the West Indies. Most of the oil is expressed in Europe, the United States and Japan, though Ceylon and India export large amounts also. In the latter part of the 20th Century there has been a trend away from consuming coconut fat because of possible harmful effects from saturated fats..
This is a white vegetable fat that is solid at room temperature and which is obtained from the seeds of the African oil palm, Elaeis guineensi, a tree of Western Africa. It has been transported worldwide and is cultivated in Haiti, Brazil and Honduras, where it is called dende. Oil palms are very productive, beginning to bear at the age of 5-6 years and reaching full bearing at 15. They continue to bear until 60-70 years of age. Each tree has 10 bunches of 200 nuts a year. The fibrous pulp of these fruit contains 30-70 percent fat. The oil was obtained mainly by crude methods for years until newer methods were developed. It is yellow-orange or brownish red in color. Most of the supply has been from Sumatra, Java and Western Africa. Palm oil is used in making soap and in the manufacture of tin plate, terne plate and cold reduced sheet steel. The refined oil is used in margarine and vegetable shortenings. It has also bee used as a fuel for diesel motors in Africa. Health conscious people have refrained in consuming this fat because, like coconut, there may be harmful effects from saturated fats.
This white and valuable oil is obtained from the kernel of the African oil palm, Elaeis guineensis. It was extensively used in the margarine and candy industries because of its pleasant odor and nutty flavor. It has also been used for making blycerin, soap, shampoos and candles. Natives in West Africa express some oil for their own use, but most of the kernels are shipped overseas. Palm-kernel cake is a good cattle feed.
During World War II when supplies of copra and palm oil were reduced, attention was directed to the rich sources in Brazil. This included over 500 species of palms, many of which are potential sources of oil. Although not native to Brazil, both coconut and the African oil palm occur there in great abundance. Additionally, several native species of palm have economic importance. These include the babasu, cohune, lieuri, tucum and murumuru palms, all of which provide kernel oils.
The most important of the New World palm oils is obtained from the babassu palms, Orbignya martiana and O. oleifera. These are magnificent trees 60 ft. in height with a vase-shaped crown of leaves. Two to eight enormous clusters of fruit are produced, each weighing about 200 lbs. and containing from 200-600 fruits. The outer portion of the fruit is a dense, tough fibrous husk. This surrounds a thin mealy mesocarp and the nut, which has a thick very hard shell. This industry was retarded when only hand labor was available to crack the nuts, but machines were developed that can exert 10,000-25,000 lb. pressure. The nuts contain from 2-6 kernels with a 63-70 percent oil content. Babassu oil is expressed from these kernels and when refined is used as a substitute for coconut oil. It is also used in making bulletproof glass, lubricants, and explosives and as a fuel for Diesel engines.
Nuts of the cohune palm, Orbignya cohune, native to Central and South America, contain 40 percent of a firm yellow fat. At one time there were over two million acres of this palm managed in British Honduras that yielded from 1,000-2,000 nutts per tree. Like the babassu, the nut is very hard to crack, but machinery has been developed.
The licuri or ouricuri palm, Syagrus coronata, occurs in dry areas of eastern Brazil. It is important commercially as the source of a palm-kernel oil and also of a wax that occurs on the leaves. The fruits resemble miniature coconuts.
The murumuru palm, Astrocaryum murumuru, is the main source of palm-kernel oil in the sate of Para, Brazil. The tucum palms, Astrocaryum tucuma and A. vulgare, or northern South America yield both a palm kernel and a pulp oil and also a fiber of commercial value.
This is the white or yellowish fat with a chocolate odor and flavor that is expressed from the beans of the cacao or cocoa, Theobroma cacao, during the process of making cocoa. It is firm at room temperature. It is used mainly for making chocolate but also for cosmetics and in perfumery and medicine.
This is a thick white or yellow oil obtained from the seeds of several species of the genus Carapa and is used for soap and as an illuminant. Natives in South America have used the oil from C. guianensis to grease their bodies and drive off insects. Carapa moluccensis is a native of East Africa, India, Sri Lanka and the Moluccas
Seeds of Butyrospermum parkii from Africa provide shea butter. It is a greenish-yellow fat with a pleasant odor and taste. The fat is also used mixed with, or as a substitute for, cocoa butter in chocolate manufacture. Inferior grades are used for soap and candles. A large amount was exported to Europe in the 20th Century.
Two species of the genus Madhuca, M. indica and M. longifolia, are the source of various products in India. They are best known as mowra fat, bassia fat, mahua butter of illipe butter. The trees are both wild and cultivated. The kernels contain 55-65 percent of soft yellow oil that is widely used locally for cooking and tallow. Over 66 million pounds were exported to Europe for use as a margarine and chocolate fat and in soap manufacturing during the 1950’s. The cake is not fit for food but is used as a fertilizer. Madhuca butyracea is the source of a similar product, phulwara butter, also used locally.
This is a hard yellowish-green and brittle solid fat sometimes known as green butter. It is obtained from Shorea aptera and some other species of the same or allied genera native to the East Indies. The kernels contain 50-70 percent fat. They are dried and expressed by the local people for their own use or are exported to Europe for soap making and as a substitute for cocoa butter.
This occurs as a thick layer of hard white fat on the seeds of Sapium sebiferum a tree from China. It has been introduced worldwide including the southern United States. After treatment the tallow is used in soap and candle making. The seeds contain a drying oil that has some value.
Seeds of nutmeg, Myristica fragrans, and related species contain about 40 percent of a yellow fat with the flavor and consistency of tallow. Nutmegs hate are not suitable for use in the spice trade are roasted and powdered and the oil extracted between warm plates. Several varieties of nutmeg butter have appeared in the market, all used for ointments or for candles. Mace yields a similar material.
There are many other vegetable fats used locally. Among these pongam oil from the seeds of Pongamia pinnata is used for illumination and medicine in India and Sri Lanka; macassar oil from the seeds of Schleichera oleosa, a soft yellowish-white fat in India, Sri Lanka and the East Indies for coking purposes, as a hair oil and for illumination; and ucuhuba and otoba butter obtained from species of Virola in northern South America.
Members of the Flacourtiaceae in Asia, Afric and South America have oily seeds that contain chaulmoogric and usually hydnocarpic acid. The natives in treating skin diseases have used these oils. The most important one, chaulmoogra oil, are discussed under Medicinal Plants
Waxes usually occur on the epidermis of leaves and fruits where they serve to prevent water loss through transpiration. The impervious waxes are harder than fats and have a higher melting point. They do not become rancid and are less easily hydrolyzed. Chemically waxes are similar to fats, but they are esters of monohydric alcohols rather than glycerides. Very few are of commercial importance.
Carnauba is the most important vegetable wax. It occurs as exudations on the leaves of the wax palm, Copernica cerifera, native to Brazil and other areas in tropical South America. The slender fan palm is called “Tree of Life” locally because almost all parts of the pant are useful. The commercial supply of carnauba wax is obtained from wild trees in northeastern Brazil. Young leaves are carefully gathered before they are fully open. They are dried in the sun for several days until the wax has turned to a flourlike dust. This is then removed by threshing. It is then melted down in clay vessels, followed by straining, cooling and forming into cakes or broken into small pieces for shipment. There are several grades. The crude product is greenish-gray and very hard with a high melting point.
Carnauba wax is used in the manufacture of candles, soap, high-luster varnishes, paints, carbon paper, batteries, sound films, insulation, salves, ointments and previously phonograph records.
The trunk of Ceroxylon andicola of the Andean Region produces a similar wax, which has been used as a substitute.
Candelilla is from Euphorbia antisyphilitica, a low, light blue-green desert shrub of Texas, Mexico and Northern Central America. The tiny leaves are quickly deciduous. The wax exudes from pores and forms a thin film on the stems. The amount produced increases during winter, so that the plants are collected in that season. The principal source is from wild plants. The wax is extracted by solvents or by boiling. The crude material is white, but the refined product is a light tan color and has a sweetish odor. Candelilla wax is softer, contains more resin and has a lower melting point than carnauba, and is therefore less valuable. It has been used as an extender wax in a mixture with others. Chemical treatment improves its quality, however.
Berries of the bayberry, Myrica pensylvanica, and the wax myrtle, M. cerifera, are both native to the eastern United States, and they are covered with a thick layer of wax. The material is in reality a fat rather than a wax. It is removed from the fruits by boiling in water and is used for candle and soap manufacture.
The leaves of the Cauassu, Calathea lutea, a tall herb of the lower Amazon region, are potentially an important source of a commercial wax. The wax occurs on the underside of the large leaves. Drying in the sun for only 2-3 hours is enough for the very thin scales to form, which are then removed by scraping. New wax-yielding leaves are produced within a year, while it takes 8-10 years for carnauba leaves to be renewed. Cauassu wax is similar to carnauba and can be used for the same purposes.
Jojoba is an evergreen bush, Simmondsia chinensis, of semiarid regions on the southwestern United States and northwestern Mexico. it is unique in having seeds with a 50 percent liquid wax content. This wax is suitable for polishes, candles and as a substitute for whale oil. It is also useful as an illuminant and, after processing, for several types of foods. The oil cake is an excellent livestock feed and the acornlike fruits are edible. Cultivation of jojoba increased dramatically in the United States during the latter part of the 20th Century, but has declined thereafter.
Berries of the wax tree of Japan, Rhus succedanea, and the leaves of raphia and licuri palms, sugar cane and esparto may also furnish commercial wax.
Many plants contain natural products that can serve as substitutes for soap. These are the saponins, a group of water-soluble glucosides. Such plants yield soap froth in water that forms emulsions with fats and oils and are capable of absorbing large amounts of gases such as carbon dioxide. Besides the few that are commercial important, there are many wild species that have been used locally. The most important saponin-containing plants are the following:
Quillaja saponaria, the soapbark tree, grows on the western slopes of the Andes from Peru to Chile. The commercial material is derived from dried inner bark, which is removed after the outer bark has been shaved off. The saponin content of the bark is about 9 percent. Soapbark forms a copious lather in water and is used in washing delicate fabrics. It was one of the best emergency materials for cleaning lenses and precision instruments during World War II. In medicine it has been used as an expectorant and emulsifying agent. However, it is a dangerous drug to take internally. Being very toxic it tends to dissolve the blood corpuscles. Therefore, its use to increase the foaming power of beer and other beverages is discouraged. Soapbark is also a good coetaneous stimulant and is often used in hair tonics.
Saponaria officinalis is a plant native to Eurasia but has become naturalized in North America. It contains a considerable amount of saponin. When placed in water the leaves produce a lather, which is utilized for washing silks and woolens. It not only cleanses but imparts a luster as well.
These are fruits of a tropical American tree, Sapindus saponaria, that occur as several subspecies from South Texas south. They are used as soap substitutes and in the preparation of hair tonics.
Bulbs of the California soaproot, Chlorogalum pomeridianum, yield a good lather and have been used locally to wash fabrics.