Stillingia oil is an

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

extracted (by

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

s) from the seeds of plants of the ''

Triadica ''Triadica'' is a plant genus of the family Euphorbiaceae first described as a genus in 1790. It is native to eastern southeastern, and southern Asia. Species included are: # '' Triadica cochinchinensis'' Lour. - China (Anhui, Fujian, Guangdong, ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

such as ''

Triadica sebifera ''Triadica sebifera'' is a tree native to eastern Asia (Chinese 乌桕, wū jiù). It is commonly called Chinese tallow, Chinese tallowtree, Florida aspen, chicken tree, gray popcorn tree, or candleberry tree. The seeds (as well as from those o ...

'' (Chinese tallow tree) and ''

Triadica cochinchinensis ''Triadica cochinchinensis'' is a species of tree known as the mountain tallow tree. The seeds (as well as from those of ''Triadica sebifera'') are the sources of stillingia oil, a drying oil used in paints and varnishes. The fatty coat of the ...

'' (Mountain tallow tree). It is a

drying oil Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be conside ...

used in

paints Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...

and

varnishes Varnish is a clear transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmented as desired. It is so ...

, and it is believed to be toxic in

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. It must be distinguished from

stillingia tallow Stillingia tallow or Chinese vegetable tallow is a fatty substance extracted from the coat of the seeds of ''Triadica sebifera'' (Chinese tallow tree) or '' Triadica cochinchinensis'' (Mountain tallow tree). It has traditionally been used for maki ...

, a fatty substance that surrounds the seeds in the fruit and must be removed before extracting the oil. The name of the oil was given when the two plants were classified in the genus ''

Stillingia ''Stillingia'' is a plant genus of the family (biology), family Euphorbiaceae, first described for modern science as a genus in 1767. The genus is native to Latin America, the southern United States, and various islands in the Pacific Ocean, Paci ...

'', with

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

s "''Stillingia sebifera''" and "''Stillingia discolor''". Sometime prior to 1950 the species were reclassified in the genus ''

Sapium ''Sapium'' is a genus of flowering plants in the family Euphorbiaceae. It is widespread across most of Latin America and the West Indies. Many Old World species were formerly included in the genus, but recent authors have redistributed all the O ...

'', and articles from the 1950s still use the names "''Sapium sebiferum''" and "''Sapium discolor''" However, since about 2002 the plants have been reclassified again in the genus ''

'', and the second one had its species name changed to "''cochinchinensis''". Stillingia oil has a typical drying time of 4–6 hours. The seeds produce 20-30% w/w of tallow fat and 10-17% w/w of stillingia oil. It has

iodine number Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vio ...

127, a

saponification Saponification is a process of cleaving esters into carboxylate salts and Alcohol (chemistry), alcohols by the action of aqueous alkali. Typically aqueous sodium hydroxide solutions are used. It is an important type of alkaline hydrolysis. When the ...

value of 206, and a thiocyanogen value of 100.7.

Composition

The composition of the oil may vary considerably with the age of the seeds (which can remain on the tree for a year after maturation) and with the extraction process. The major components of typical fresh oil are

triglycerides A triglyceride (from ''wikt:tri-#Prefix, tri-'' and ''glyceride''; also TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids. Triglycerides are the main constituents of body fat in humans and oth ...

of the following fatty acids: (a) Fatty acid codes used in the discussion below.
(b) Molar percentages.
Several analyses of authentic oil in the 1950s found significant amounts of 2.4-decadienoic acid, later identified as the ''trans''-2, ''cis''-4 isomer, which had not been detected in natural oils before, and was conjectured to play a relatively prominent part in the drying and polymerizing properties of stillingia oil. Another analysis (1992) found that the

tocopherol Tocopherols (; TCP) are a class of organic compounds comprising various methylated phenols, many of which have vitamin E activity. Because the vitamin activity was first identified in 1936 from a dietary fertility factor in rats, it was named ''t ...

fraction contains nearly pure (92%) γ-tocotrienol. According to a 1953 analysis of authentic oil, 64% (by mass) of the oil's triglycerides have three unsaturated

acyl In chemistry, an acyl group is a moiety derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids. It contains a double-bonded oxygen atom and an organyl group () or hydrogen in the case of formyl grou ...

s connected to the

glycerol Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...

hub, 34% have two, and about 2% have just one. The most common triglyceride component, with over half the mass, had (1) one linoleic and two linolenic acyls, or LNN or NLN using the codes of the table above. The next two most common types have a 2,4-decadienoic acyl on the second carbon of the

hub, flanked by (2) one linoleic and one linolenic acyl (LDN), or (3) two linolenic acyls (NDN). The 2,4-decadienoic acyl occurs almost exclusively in those two components. There are smaller proportions of triglycerides with (4) one saturated, one linoleic, and one linolenic (XLN, LXN, etc.); (5) one saturated and two linolenic; (XNN or NXN) (6) one oleic, one linoleic, one linolenic (OLN, LON, etc.); and (7) one oleic and two linolenic (ONN o NON). Over 95% of the triglycerides in stillingia oil were found to have three doubly-unsaturated fatty acids. This proportion is greater than that of

linseed oil Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colorless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...

, and comparable with that in conophor oil. An analysis in 1992 found that an 8-hydroxy-5,6-octadienoic acid was joined to by an estolide linkage to the 2,4-decadienoic acyl. A more recent analysis (2009) of commercial oil found instead 80% (molar) of LLN, 14% PLN, 3% PPL, 1.5 RPL, and 0.5 SLN. This analysis also failed to find the 2,4-decadienoic acid. Instead it found twice as much oleic acid (16%), 3.5% of lauric acid, and 1.8% of heptadecanoic acid; as well as 1% (by weight) of

phospholipid Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...

s and about 0.3% of

glycolipid Glycolipids () are lipids with a carbohydrate attached by a glycosidic (covalent) bond. Their role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the c ...

s. No explanation was given for these discrepancies.

References

Ya-Chi Chen, A. Zlatkis, B. S. Middleditch, J. Cowles, and W. Scheld (1987): "Lipids of contemporary stillingia oil". ''Chromatographia'', volume 23, pages 240–242. B. S. J. Jeffrey F. B. Padley (1991): "Chinese vegetable tallow - Characterization and contamination by stillingia oil". ''Journal of the American Oil Chemists' Society'', Yun Liu, Hong-lingXin, and Yun-junYan (2009): "Physicochemical properties of stillingia oil: Feasibility for biodiesel production by enzyme transesterification". ''Industrial Crops and Products'', volume 30, issue 3, pages 431-436. K. Aitzetmüller, Yaonian Xin, Gisela Werner, and Margaretha Grönheim (1992): "High-performance liquid chromatographic investigations of stillingia oil". ''Journal of Chromatography A'', volume 603, issues 1–2, pages 165-173. Hans-Joachim Esser (2002)
"A revision of ''Triadica'' Lour. (Euphorbiaceae)"
''Harvard Papers in Botany'', volume 7, issue 1, pages 17-21 (5 pages) A. Crossley and T. P. Hilditch (1950): "The component acids of some authentic and commercial stillingia oils". ''Journal of the Science of Food and Agriculture'', volume 1, issue 10, pages 292–300. J. Devine (1950): "The composition of stillingia oil and the presence therein of 2:4-decadienoic acid". ''Journal of the Science of Food and Agriculture'', volume 1, issue 3, pages 88–92. A. Crossley and T. P. Hilditch (1953): "The component glycerides of stillingia oil". ''Journal of the Science of Food and Agriculture'', volume 4, pages 38–44, {{doi, 10.1002/jsfa.2740040107

FAO The Food and Agriculture Organization of the United Nations; . (FAO) is a List of specialized agencies of the United Nations, specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition ...

(1994):
Vegetable and animal oils and fats
. Chapter in ''Definition and Classification of Commodities''. Accessed on 2006-11-19. Vegetable oils