![Adriaen Coorte - Two Walnuts](https://upload.wikimedia.org/wikipedia/commons/2/2f/Adriaen_Coorte_-_Two_Walnuts.jpg)
A walnut is the edible seed of a
drupe
In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...
of any
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
of the genus ''
Juglans
Walnut trees are any species of tree in the plant genus ''Juglans'', the type genus of the family Juglandaceae, the seeds of which are referred to as walnuts. All species are deciduous trees, tall, with pinnate leaves , with 5–25 leaflets; t ...
'' (family
Juglandaceae
The Juglandaceae are a plant family known as the walnut family. They are trees, or sometimes shrubs, in the order Fagales. Members of this family are native to the Americas, Eurasia, and Southeast Asia.
The nine or ten genera in the family have ...
), particularly the Persian or English walnut, ''
Juglans regia
''Juglans regia'', the Persian walnut, English walnut, Carpathian walnut, Madeira walnut, or especially in Great Britain, common walnut, is an Old World walnut tree species native to the region stretching from the Balkans eastward to the Himalay ...
''.
Although culinarily considered a "nut" and used as such, it is not a true
botanical nut
A nut is a fruit consisting of a hard or tough nutshell protecting a kernel which is usually edible. In general usage and in a culinary sense, a wide variety of dry seeds are called nuts, but in a botanical context "nut" implies that the shell ...
. After full ripening, the
shell
Shell may refer to:
Architecture and design
* Shell (structure), a thin structure
** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses
** Thin-shell structure
Science Biology
* Seashell, a hard ou ...
is discarded and the kernel is eaten. Nuts of the eastern black walnut (''
Juglans nigra
''Juglans nigra'', the eastern American black walnut, is a species of deciduous tree in the walnut family, Juglandaceae, native to North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to ...
'') and butternuts (''
Juglans cinerea
''Juglans cinerea'', commonly known as butternut or white walnut,Snow, Charles Henry ''The Principal Species of Wood: Their Characteristic Properties'' 2nd ed. New York: John Wiley & Sons, 1908. p. 56. is a species of walnut native to the e ...
'') are less commonly consumed.
Characteristics
Walnuts are rounded, single-seeded
stone fruits
In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...
of the walnut tree commonly used for food after fully ripening between September and November, in which the removal of the husk at this stage reveals a browning wrinkly walnut shell,
which is usually commercially found in two segments (three or four-segment shells can also form). During the ripening process, the husk will become brittle and the shell hard. The shell encloses the kernel or meat, which is usually made up of two halves separated by a membranous partition.
The seed kernels – commonly available as shelled walnuts – are enclosed in a brown
seed coat
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm pl ...
which contains antioxidants. The antioxidants protect the oil-rich seed from atmospheric oxygen, thereby preventing
rancidity
Rancidification is the process of complete or incomplete autoxidation or hydrolysis of fats and oils when exposed to air, light, moisture, or bacterial action, producing short-chain aldehydes, ketones and free fatty acids.
When these processes oc ...
.
Walnut trees are late to grow leaves, typically not leafing out until more than halfway through the spring. They
emit chemicals into the soil to prevent competing vegetation from growing. Because of this, susceptible plants should not be planted close to them.
History and cultivation
During the
Byzantine era
The Byzantine calendar, also called the Roman calendar, the Creation Era of Constantinople or the Era of the World ( grc, Ἔτη Γενέσεως Κόσμου κατὰ Ῥωμαίους, also or , abbreviated as ε.Κ.; literal translation of ...
, the walnut was also known by the name "royal nut". An article on walnut tree cultivation in
Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, i ...
is included in
Ibn al-'Awwam
Ibn al-'Awwam ( ar, ابن العوام), also called Abu Zakariya Ibn al-Awwam ( ar, أبو زكريا بن العوام), was a Muslim Arab agriculturist who flourished at Seville (modern-day southern Spain) in the later 12th century. He wrote a ...
's 12th-century ''Book on Agriculture''. The walnut was originally known as the ''Welsh nut'', i.e. it came through France and/or Italy to Germanic speakers (German , Dutch or , Danish , Swedish ). In Polish translates to "Italian nuts" ( being the adjectival form of ("Italy")).
Types
The two most common major species of walnuts are grown for their seeds – the Persian or English walnut and the black walnut. The English walnut (''J. regia'') originated in
Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
(
Persia
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
), and the black walnut (''J. nigra'') is native to eastern
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
. The black walnut is of high flavor, but due to its hard shell and poor hulling characteristics it is not commercially cultivated in orchards.
Numerous walnut
cultivars
A cultivar is a type of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and when Plant propagation, propagated retain those traits. Methods used to propagate cultivars include: division, root and st ...
have been developed commercially, which are nearly all hybrids of the English walnut.
Other species include ''
J. californica'', the
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
black walnut (often used as a
rootstock
A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to a ...
for commercial propagation of ''J. regia''), ''J. cinerea'' (butternuts), and ''J. major'', the Arizona walnut. Other sources list ''J. californica californica'' as native to southern California, and ''Juglans californica hindsii'', or just ''J. hindsii'', as native to northern California; in at least one case, these are given as "geographic variants" instead of subspecies (Botanica).
Production
In 2020, world production of walnuts (in shell) was 3.3 million
tonnes
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United States ...
, with
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
contributing 33% of the total (table). Other major producers (in the order of decreasing harvest) were the United States,
Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
, and
Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
.
[
]
Storage
Walnuts, like other tree nuts, must be processed and stored properly. Poor storage makes walnuts susceptible to insect and fungal mold infestations; the latter produces aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
– a potent carcinogen. A batch which contains mold-infested walnuts should be entirely discarded.
The ideal temperature for the extended storage of walnuts is with low humidity for industrial and home storage. However, such refrigeration technologies are unavailable in developing countries where walnuts are produced in large quantities; there, walnuts are best stored below with low humidity. Temperatures above , and humidities above 70 percent can lead to rapid and high spoilage losses. Above 75 percent humidity threshold, fungal molds that release dangerous aflatoxin can form.
Food use
Walnut meats are available in two forms: in their shells or de-shelled. The meats may be whole, halved, or in smaller portions due to processing. All walnuts can be eaten on their own (raw, toasted or pickled), or as part of a mix such as muesli
Muesli ( ) is a cold breakfast dish, the primary ingredient of which is rolled oats, which is set to soak overnight and eaten the next morning. Most often, additional ingredients such as grains, nuts, seeds, and fresh or dried fruits, are added, ...
, or as an ingredient of a dish: e.g. walnut soup
Walnut soup is a broth-based or cream-based soup prepared using walnuts as a main ingredient. It is sometimes prepared in combinations using other ingredients, such as "pumpkin and walnut soup". Walnut soup is a part of the cuisines of China, Ital ...
, walnut pie
Walnut pie is a pie prepared with walnuts as a primary ingredient. Whole or chopped walnuts may be used, or both, and toasted walnuts may be used. It may be prepared as a cream pie, and may include maple syrup, molasses, and cinnamon as ingredient ...
, walnut coffee cake, banana cake
A banana cake is a cake prepared using banana as a primary ingredient and typical cake ingredients. It can be prepared in various manners, including as a layer cake, as muffins and as cupcakes. Steamed banana cake is found in Chinese, Indonesi ...
, brownie, fudge
Fudge is a type of confection that is made by mixing sugar, butter and milk, heating it to the soft-ball stage at , and then beating the mixture while it cools so that it acquires a smooth, creamy consistency. In texture, this crystalline cand ...
. Walnuts are often candied or pickled. Pickled walnuts that are the whole fruit can be savory or sweet depending on the preserving solution.
Walnuts may be used as an ingredient in other foodstuffs. Walnut is an important ingredient in baklava
Baklava (, or ; ota, باقلوا ) is a layered pastry dessert made of filo pastry, filled with chopped nuts, and sweetened with syrup or honey. It was one of the most popular sweet pastries of Ottoman cuisine.
The pre- Ottoman origin of the ...
, Circassian chicken
Circassian chicken ( Adyghe: ''Jed de ships sch'etu'') is a dish of shredded boiled chicken served under or in a rich paste made with crushed walnuts, and stock thickened with stale bread. Circassian Chicken is a classic Circassian dish, adopted ...
, chicken in walnut sauce, and poultry or meat ball stew
A stew is a combination of solid food ingredients that have been cooked in liquid and served in the resultant gravy. A stew needs to have raw ingredients added to the gravy. Ingredients in a stew can include any combination of vegetables and ...
from Iranian cuisine
Iranian cuisine () refers to the culinary practices of Iran. Due to the historically common usage of the term "Persia" to refer to Iran in the Western world,Yarshater, EhsaPersia or Iran, Persian or Farsi, ''Iranian Studies'', vol. XXII no. 1 ( ...
.
Walnuts are also popular as an ice cream
Ice cream is a sweetened frozen food typically eaten as a snack or dessert. It may be made from milk or cream and is flavoured with a sweetener, either sugar or an alternative, and a spice, such as cocoa or vanilla, or with fruit such as str ...
topping, and walnut pieces are used as a garnish on some foods.
Nocino
Nocino is a dark brown liqueur from the Emilia-Romagna region in northern Italy. It is made from unripe green walnuts. The walnuts and the liquor are handled using ceramic or wooden tools (to avoid oxidation) and placed in an alcoholic base. Aft ...
is a liqueur
A liqueur (; ; ) is an alcoholic drink composed of spirits (often rectified spirit) and additional flavorings such as sugar, fruits, herbs, and spices. Often served with or after dessert, they are typically heavily sweetened and un-aged beyond ...
made from unripe green walnuts steeped in alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
with syrup added.
Walnut oil
Walnut oil is oil extracted from walnuts, ''Juglans regia''. The oil contains polyunsaturated fatty acids, monounsaturated fatty acids, and saturated fats.
Composition
Walnut oil is composed largely of polyunsaturated fatty acids (72% of total ...
is available commercially and is chiefly used as a food ingredient particularly in salad dressings
A salad dressing is a sauce for salads. Used on virtually all '' leafy salads'', dressings may also be used in making salads of beans (such as three bean salad), noodle or pasta salads and antipasti, and forms of potato salad.
Salad dressings c ...
. It has a low smoke point
The smoke point, also referred to as the burning point, is the temperature at which an oil or fat begins to produce a continuous bluish smoke that becomes clearly visible, dependent upon specific and defined conditions. Smoke point values can va ...
, which limits its use for frying
Frying is the cooking of food in oil or another fat. Similar to sautéing, pan-fried foods are generally turned over once or twice during cooking to make sure that the food is well-made, using tongs or a spatula, while sautéed foods are cooked ...
.
Nutritional value
Walnuts without shells are 4% water, 15% protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
, 65% fat
In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food.
The term often refers spec ...
, and 14% carbohydrates
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may ...
, including 7% dietary fiber
Dietary fiber (in British English fibre) or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition, and can be grouped generally by the ...
(table). In a 100-gram reference serving, walnuts provide and rich content (20% or more of the Daily Value
The Reference Daily Intake (RDI) used in nutrition labeling on food and dietary supplement products in the U.S. and Canada is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of health ...
or DV) of several dietary minerals
In the context of nutrition, a mineral is a chemical element required as an essential nutrient by organisms to perform functions necessary for life. However, the four major structural elements in the human body by weight (oxygen, hydrogen, carbon, ...
, particularly manganese
Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
at 163% DV, and B vitamins
B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. Though these vitamins share similar names (B1, B2, B3, etc.), they are chemically distinct compounds that often coexist ...
(table).
While English walnuts are the most commonly consumed, their nutrient density and profile are generally similar to those of black walnuts.
Unlike most nuts, which are high in monounsaturated fatty acids
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple est ...
, walnut oil
Walnut oil is oil extracted from walnuts, ''Juglans regia''. The oil contains polyunsaturated fatty acids, monounsaturated fatty acids, and saturated fats.
Composition
Walnut oil is composed largely of polyunsaturated fatty acids (72% of total ...
is composed largely of polyunsaturated fatty acids
Polyunsaturated fatty acids (PUFAs) are fatty acids that contain more than one double bond in their backbone. This class includes many important compounds, such as essential fatty acids and those that give drying oils their characteristic proper ...
(72% of total fats), particularly alpha-linolenic acid
''alpha''-Linolenic acid (ALA), also known as α-Linolenic acid (from Greek ''alpha'' meaning "first" and ''linon'' meaning flax), is an ''n''−3, or omega-3, essential fatty acid. ALA is found in many seeds and oils, including flaxseed, waln ...
(14%) and linoleic acid
Linoleic acid (LA) is an organic compound with the formula COOH(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are cis-trans isomerism, ''cis''. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 ''cis''-9,12. A linoleate is a salt (chem ...
(58%), although it does contain 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. In chemical terms, oleic acid is classified as a monounsaturated omega ...
as 13% of total fats.
Health claims
In 2016, the US Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) provided a ''Qualified Health Claim'' allowing products containing walnuts to state: "Supportive but not conclusive research shows that eating per day of walnuts, as part of a low saturated fat
A saturated fat is a type of fat in which the fatty acid chains have all single bonds. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branched c ...
and low cholesterol
Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
diet and not resulting in increased caloric intake, may reduce the risk of coronary heart disease
Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of atherosclerotic pla ...
." The FDA had, in 2004, refused to authorize the claim that "Diets including walnuts can reduce the risk of heart disease" and had sent an FDA Warning Letter An FDA warning letter is an official message from the United States Food and Drug Administration (FDA) to a manufacturer or other organization that has violated some rule in a federally regulated activity.
The FDA defines an FDA warning letter as: ...
to Diamond Foods
Diamond Foods was an American packaged food company based in San Francisco, that marketed nuts (particularly walnuts and almonds) and other snack foods. Diamond Foods was acquired by Snyder's-Lance in 2016, and as of 2018, Campbell Soup Company ...
in 2010 stating there is "not sufficient evidence to identify a biologically active substance in walnuts that reduces the risk of coronary heart disease." A recent systematic review assessing the effect of walnut supplementation on blood pressure (BP) found insufficient evidence to support walnut consumption as a BP-lowering strategy.
As of 2021, the relationship between walnuts and cognitive health is inconclusive.
Non-food applications
Juice from boiled walnuts can be used as an antifungal
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as crypto ...
agent. Green husks can be crushed and sprinkled into water to poison fish.
Folk medicine
Walnuts have been listed as one of the 38 substances used to prepare Bach flower remedies
Bach flower remedies (BFRs) are solutions of brandy and water—the water containing extreme dilutions of flower material developed by Edward Bach, an English homeopath, in the 1930s. Bach claimed that the dew found on flower petals retains t ...
, a herbal remedy
Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remedies ...
promoted in folk medicine practices for its supposed effect on health. According to Cancer Research UK
Cancer Research UK (CRUK) is the world's largest independent cancer research organization. It is registered as a charity in the United Kingdom and Isle of Man, and was formed on 4 February 2002 by the merger of The Cancer Research Campaign and t ...
, "there is no scientific evidence to prove that flower remedies can control, cure or prevent any type of disease, including cancer".
Inks and dyes
Walnut husks can be used to make a durable ink for writing and drawing. It is thought to have been used by artists including Leonardo da Vinci
Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, Drawing, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially res ...
and Rembrandt
Rembrandt Harmenszoon van Rijn (, ; 15 July 1606 – 4 October 1669), usually simply known as Rembrandt, was a Dutch Golden Age painter, printmaker and draughtsman. An innovative and prolific master in three media, he is generally consid ...
.
Walnut husk pigments are used as a brown dye
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...
for fabric and were used in classical Rome
In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...
and medieval Europe
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
for dyeing hair
Hair coloring, or hair dyeing, is the practice of changing the hair color. The main reasons for this are beauty, cosmetic: to cover Gray hair, gray or white hair, to change to a color regarded as more fashionable or desirable, or to restore the or ...
.
Woodworking
The fine, straight-grained wood of the black walnut is highly valued as furniture wood, wall paneling, automobile interiors, and for gunstocks.
Cleaning
The United States Army
The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...
once used ground walnut shells for abrasive blasting
Sandblasting, sometimes known as abrasive blasting, is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove su ...
to clean aviation parts because of low cost and low abrasive qualities. However, an investigation of a fatal Boeing CH-47 Chinook
The Boeing CH-47 Chinook is a tandem rotor helicopter developed by American rotorcraft company Vertol and manufactured by Boeing Vertol. The Chinook is a heavy-lift helicopter that is among the heaviest lifting Western helicopters. Its name, Ch ...
helicopter crash (September 11, 1982, in Mannheim, Germany) revealed that walnut shell grit had clogged an oil port, leading to the accident and the discontinuation of walnut shells as a cleaning agent. Commercially, crushed walnut shells are still used outside of aviation for low-abrasive, less-toxic cleaning and blasting applications.
Phytochemicals
Walnut hulls contain diverse phytochemical
Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as poisons ...
s, such as polyphenols
Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some of ...
that stain hands and can cause skin irritation. Seven phenolic compounds, including ferulic acid
Ferulic acid is a hydroxycinnamic acid, an organic compound with the formula (CH3O)HOC6H3CH=CHCO2H. The name is derived from the genus ''Ferula'', referring to the giant fennel (''Ferula communis''). Classified as a phenolic phytochemical, ferulic ...
, vanillic acid
Vanillic acid (4-hydroxy-3-methoxybenzoic acid) is a dihydroxybenzoic acid derivative used as a flavoring agent. It is an oxidized form of vanillin. It is also an intermediate in the production of vanillin from ferulic acid.
Occurrence in natu ...
, coumaric acid Coumaric acid is a phenolic derivative of cinnamic acid having a hydroxy group
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In ...
, syringic acid
Syringic acid is a naturally occurring phenolic compound and dimethoxybenzene that is commonly found as a plant metabolite.
Natural occurrence
Syringic acid can be found in several plants including ''Ardisia elliptica'' and '' Schumannianthus d ...
, myricetin
Myricetin is a member of the flavonoid class of polyphenolic compounds, with antioxidant properties. Common dietary sources include vegetables (including tomatoes), fruits (including oranges), nuts, berries, tea, and red wine. Myricetin is structu ...
, and juglone
Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) is an organic compound with the molecular formula C10H6O3. In the food industry, juglone is also known as C.I. Natural Brown 7 and C.I. 75500. It is insoluble in benzene but soluble i ...
were identified in walnut husks. Juglone, the predominant phenolic, was found in concentrations of 2-4% fresh weight.
Walnuts also contain the ellagitannin pedunculagin
Pedunculagin is an ellagitannin. It is formed from casuarictin via the loss of a gallate group.
Natural occurrence
Pedunculagin is found in plants in orders in the clade Rosidae. It can be found the pericarp of pomegranates (''Punica granatum' ...
. Regiolone has been isolated with juglone, betulinic acid
Betulinic acid is a naturally occurring pentacyclic triterpenoid which has antiretroviral, antimalarial, and anti-inflammatory properties, as well as a more recently discovered potential as an anticancer agent, by inhibition of topoisomerase. I ...
and sitosterol
β-sitosterol (beta-sitosterol) is one of several phytosterols (plant sterols) with chemical structures similar to that of cholesterol. It is a white, waxy powder with a characteristic odor, and is one of the components of the food additive E499. ...
from the stem bark of ''J. regia''.
Chinese culture
Large, symmetrically shaped, and sometimes intricately carved walnut shells (mainly from '' J. hopeiensis'' ) are valued collectibles in China where they are rotated in the hand as a plaything or as decoration. They are also an investment
Investment is the dedication of money to purchase of an asset to attain an increase in value over a period of time. Investment requires a sacrifice of some present asset, such as time, money, or effort.
In finance, the purpose of investing i ...
and status symbol
A status symbol is a visible, external symbol of one's social position, an indicator of economic or social status. Many luxury goods are often considered status symbols. ''Status symbol'' is also a sociological term – as part of social and soci ...
, with some carvings having high monetary value
In economics, economic value is a measure of the benefit provided by a good or service to an economic agent. It is generally measured through units of currency, and the interpretation is therefore "what is the maximum amount of money a specif ...
if unique. Pairs of walnuts are sometimes sold in their green husks for a form of gambling known as ''du qing pi''.
Cultivars
Gallery
File:Juglans regia 2009 G2.jpg, Common walnut in growth
File:California Blackwalnut.jpg, California black walnut
''Juglans californica'', the California black walnut, also called the California walnut, or the Southern California black walnut, is a large shrub or small tree (about 20-49 feet tall) of the walnut family, Juglandaceae, endemic to Southern Calif ...
in growth
File:Juglans regia polyploid fruit bottom.jpg, A three-segment shell which occurs rarely
File:Noix3coquilles.jpg, Walnut in shell and a nutcracker
A nutcracker is a tool designed to open nuts by cracking their shells. There are many designs, including levers, screws, and ratchets. The lever version is also used for cracking lobster and crab shells.
A decorative version portrays a person w ...
utensil used to break the shell
File:Benutzung eines Nussknackers.gif, Video of cracking a walnut
File:Walnuts no shell.jpg, Walnut meats
File:Cerneaux de noix.jpg, Broken walnut meats
File:Gozinaki with walnuts.jpg, Georgian
Georgian may refer to:
Common meanings
* Anything related to, or originating from Georgia (country)
** Georgians, an indigenous Caucasian ethnic group
** Georgian language, a Kartvelian language spoken by Georgians
**Georgian scripts, three scrip ...
snack Gozinaki
Gozinaki or Gozinaqi ( ka, გოზინაყი ) is a traditional Georgian confection made of caramelized nuts, usually walnuts, fried in honey, and served exclusively on New Year's Eve and Christmas. In the western Georgian provinces of I ...
made from roasted walnuts and honey
File:Applesauce walnut coffee cake.jpg, Applesauce
Apple sauce or applesauce is a purée (not necessarily served as a true sauce) made of apples. It can be made with peeled or unpeeled apples and may be spiced or sweetened. Apple sauce is inexpensive and is widely consumed in North America and s ...
coffee cake
Coffee cake may refer to a sponge cake flavored with coffee or, in the United States, a sweet cake intended to be eaten with coffee or tea (similar to tea cake). A coffee-flavored cake is typically baked in a circular shape with two layers separ ...
garnished with walnuts
File:A Pair Of Chnese Collectible Walnuts.jpg, Walnuts as collectibles
File:Walnut murabba.jpg, Murabba
Murabba (from ar, مربى) refers to a sweet fruit preserve which is popular in many regions of South Caucasus, Central Asia, South Asia, and the Middle East
The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolit ...
made from young walnuts
See also
* Kurumi
is the Japanese word for walnut. It is also a given name in Japan, primarily for women (though occasionally for men, such as novelist Kurumi Inui). It may refer to:
People Actors
*, female child actress
*, female voice actress
*, female actress, ...
* List of unproven and disproven cancer treatments
This is a non-exhaustive list of alternative treatments that have been promoted to treat or prevent cancer in humans but which lack scientific and medical evidence of effectiveness. In many cases, there is scientific evidence that the alleged tr ...
References
Further reading
*
*
External links
*
{{Nuts
Crops
Edible nuts and seeds
Fruit trees
Plant dyes
Symbols of California