Walnut oil is oil extracted from walnuts, ''

Juglans regia ''Juglans regia'', known by various common names including the common walnut, English walnut, or Persian walnut amongst other names, is a species of walnut. It is native to Eurasia in at least southwest and central Asia and southeast Europe, ...

''. The oil contains

polyunsaturated fatty acids In biochemistry and nutrition, a polyunsaturated fat is a fat that contains a polyunsaturated fatty acid (abbreviated PUFA), which is a subclass of fatty acid characterized by a backbone with two or more carbon–carbon double bonds. Some polyunsa ...

, monounsaturated fatty acids, and saturated fats.

Composition

According to gas chromatographic and HPLC analysis, virgin walnut oil consists of

linoleic acid Linoleic acid (LA) is an organic compound with the formula . Both alkene groups () are ''cis''. It is a fatty acid sometimes denoted 18:2 (n−6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid. Linoleic acid is a polyunsat ...

(60–62%). It also contains many phenolc compounds including γ-tocopherol, tanins, and flavanoids. Several of these exhibit

antioxidant Antioxidants are Chemical compound, compounds that inhibit Redox, oxidation, a chemical reaction that can produce Radical (chemistry), free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants ...

properties. According to another source, walnut oil is composed largely of polyunsaturated fatty acids (72% of total fats), particularly alpha-linolenic acid (14%) and

(58%),

oleic acid Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish due to the presence of impurities. In chemical terms, oleic acid is cl ...

(13%), and saturated fats (9%). Walnuts typically contain high concentrations of phenolics including

ellagic acid Ellagic acid is a polyphenol found in numerous fruits and vegetables. It is the dilactone of hexahydroxydiphenic acid. Name The name comes from the French term ''acide ellagique'', from the word ''galle'' spelled backward because it can be o ...

Culinary use

Walnut oil is edible and is generally used less than other oils in

food preparation {{catexp, articles about specific foodstuffs. See :Food and drink for more general topics relating to food. Food watchlist articles ...

, often due to high pricing. It is light-coloured and delicate in flavour and scent, with a nutty quality. Although chefs sometimes use walnut oil for pan-frying, most avoid walnut oil for high-temperature cooking because heating tends to reduce the oil's flavour and produce a slight bitterness. Walnut oil is preferred in cold dishes such as salad dressings. Cold-pressed walnut oil is typically more expensive due to the loss of a higher percentage of the oil. Refined walnut oil is expeller-pressed and saturated with solvent to extract the highest percentage of oil available in the nut meat. The solvents are subsequently eliminated by heating the mixture to around . Both methods produce food-grade culinary oils. Walnut oil, like all nut, seed and vegetable oils can turn rancid. Over 99% of walnut oil sold in the US is produced in California.

Artistic use

Linoleic acid, the major component of walnut oil, 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 ...

", which means that in air it polymerizes, forming strong but flexible films, useful in

oil paint Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. Oil paint also has practical advantages over other paints, mainly because it is waterproof. The earliest surviving ...

s and

varnish Varnish is a clear Transparency (optics), 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 pigmente ...

es. Walnut oil was one of the most important oils used by

Renaissance The Renaissance ( , ) is a Periodization, period of history and a European cultural movement covering the 15th and 16th centuries. It marked the transition from the Middle Ages to modernity and was characterized by an effort to revive and sur ...

painters. Its short drying time and lack of yellow tint make it a good

base thinner and brush cleaner. Some woodworkers favour walnut oil as a finish for implements that will come in contact with food, such as wooden bowls, because of its safety. Rancidity is not an issue because walnut oil dries when applied to wood in a thin coating. People who mix oil and wax to formulate wood finishes value walnut oil as an ingredient because of the edibility of both ingredients. The oil typically is combined with beeswax in a mixture of 1/3 oil to 2/3 beeswax.

References

{{fatsandoils Nut oils Cooking oils Painting materials Wood finishing materials Oil