Nut (fruit)
A
nut is a
seed of a
plant.
A
nut in
botany is a
simple dry fruit with one
seed (rarely two) in which the ovary wall becomes very hard (stony or woody) at maturity, and where the seed remains unattached or unfused with the ovary wall. Most nuts come from
pistils with
inferior ovaries (see
flower) and all are
indehiscent (not opening at maturity). True nuts are produced - for example - by some plants-families of the
order Fagales. Note that not all true nuts are edible; some (e.g.
birch,
alder,
hornbeam,
wingnut) are too small to be worth eating, while others (e.g.
tanoak) are too
bitter to be
edible.
Order Fagales
*Family Juglandaceae
**Walnut, Butternut (Juglans)
**Hickory, Pecan (Carya)
**Wingnut (Pterocarya)
*Family Fagaceae
**Chestnut (Castanea)
**Beech (Fagus)
**Oak (Quercus)
**Stone-oak, Tanoak (Lithocarpus)
*Family Betulaceae
**Alder (Alnus)
**Birch (Betula)
**Hazel, Filbert (Corylus)
**Hornbeam (Carpinus)A
nut in
cuisine is a much less restrictive category than a nut in botany, the term being applied (or misapplied, depending upon the viewpoint) to many
seeds that are not true nuts. Any large, oily
kernel found within a shell and used in
food may be regarded as a nut. Because nuts generally have a high oil content, they are a highly prized food and energy source. A large number of seeds are edible by humans and used in cooking, eaten raw, sprouted, or roasted as a
snack food, or pressed for oil that is used in
cookery and
cosmetics. By the same token, nuts (or seeds generally) are a significant source of nutrition for wildlife. This is particularly true in temperate climates where animals such as
jays and
squirrels store
acorns and other nuts during the
autumn to keep them from starving during the winter and early spring.
|
Korean Pine pine nuts - unshelled, and shell, above; shelled, below |
Some fruits and seeds that are nuts in the culinary sense but not in the botanical sense:
*
Almond, is the edible seed of a
drupe - the leathery "flesh" is removed at harvest.
*
Brazil nuts are seeds from a
capsule.
*
Candlenut (used for oil) is a seed.
*
Cashew nuts are
seeds.
*
Coconut is a dry fibrous
drupe.
*
Corn nut is a roasted or deep fried
maize seed.
*
Horse-chestnut (not edible) is a
capsule.
*
Peanut is a
legume and a seed.
*
Pine nuts are the seeds of several species of
pine (
coniferous trees).
*
Pistachio nut is the seed of a thin-shelled
drupe.
See also: List of edible seedsAs mentioned in
Culinary definition and uses, the term nut is sometimes used on seeds, but nuts and seeds are not the same thing. A nut is a seed, but not all seeds are nuts. A seed comes from fruit and can be removed from the fruit. A nut is a compound
ovary that is both the seed and the fruit, which cannot be separated.
Besides seeds, others that are mislabeled as nuts include
legume (separate hard seeds),
drupe (contains
endocarp which contains seeds) and
capsule (dried fruit that splits to release seeds).
Allergy to nuts is a relatively common and often very serious problem. For people with nut allergy, exposure to surprisingly small amounts of nut fragments (e.g. minor cross-contamination of otherwise nut-free products in a food processing factory) can cause fatal
anaphylactic shock.
Allergy to
peanuts is the most common; some evidence suggests that peanut allergy may be related to the use of peanuts in
baby foods; if given to very young children who are not yet able to digest all the components of peanuts fully, the body will then react against those components. As the peanut is a member of the
pea family unrelated to other nuts, individuals with allergies to peanuts may not be allergic to other nuts, and those with allergies to other nuts may not be allergic to peanuts. A common term applied to nuts, used to distinguish peanuts from nuts, is "tree nuts".
Several
epidemiological studies have revealed that people who consume nuts regularly are less likely to suffer from
coronary heart disease. Recent
clinical trials have found that consumption of various nuts such as
almonds and
walnuts can lower serum
LDL cholesterol concentrations. Although nuts contain various substances thought to possess cardioprotective effects, scientists believe that their
fatty acid profile is at least in part responsible for the hypolipidemic response observed in clinical trials.
In addition to possessing cardioprotective effects, nuts generally have a very low
glycemic index (GI). Consequently, dietitians frequently recommend nuts be included in diets prescribed for patients with
insulin resistance problems such as
type 2 diabetes mellitus.
See also Chart of nutritional properties of nuts and oily seedsThe "nut" of the
horse-chestnut, (
Aesculus hippocastanum), is also known as a
conker. Conkers are inedible but are collected and used in an old children's game, also known as
conkers, in which a nut is threaded onto a strong cord and then each child attempts to break their opponent's conker by hitting it with their own. A related species,
Aesculus californica, was formerly eaten by the
Native Americans of
California in times of famine. It must be leached to remove poisonous constituents before eating.
*
Photos of some nuts*
Nut crackers*
Nutra-Smart.net Health Benefits of Nuts
*
Linus Pauling Micronutrient Information Centre Nuts
*
American Journal of Clinical Nutrition Nuts and their bioactive constituents: effects on serum lipids and other factors that affect disease risk
