A nut is a hard-shelled fruit of some plants
having an indehiscent seed. While a wide variety of dried
seeds and fruits are called nuts in English, only a certain
number of them are considered by biologists to be true nuts.
Nuts are an important source of nutrients for both humans and
wildlife.
Nuts are a composite of the seed and the fruit, where the
fruit does not open to release the seed. Most seeds come from
fruits, and the seeds are free of the fruit, unlike nuts like
hazelnuts, hickories, chestnuts and acorns, which have a stony
fruit wall and originate from a compound ovary. Culinary usage
of the term is less restrictive, and some nuts as defined in
food preparation, like pistachios and Brazil nuts,[1] are not
nuts in a biological sense. Everyday common usage of the term
often refers to any hard walled, edible kernel, as a nut.[2]
Botanical definition
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 attached or
fused with the ovary wall. Most nuts come from the pistils
with inferior ovaries (see flower) and all are indehiscent
(not opening at maturity). True nuts are produced, for
example, by some plant families of the order Fagales.
Order Fagales
Culinary definition and uses
A nut in cuisine is a much less restrictive category than a
nut in botany, as the term is applied to many seeds that are
not botanically 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. Nuts (or seeds generally) are also 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 late autumn, all
of winter, and early spring.
Nuts used for food, whether true nut or not, are among the
most common food allergens.[3]
Some fruits and seeds that do not meet the botanical
definition but are nuts in the culinary sense:
Almonds, Pecans and Walnuts are the edible seeds of drupe
fruits — the leathery "flesh" is removed at harvest.
-
Brazil nut is the seed from a capsule.
-
Candlenut (used for oil) is a seed.
-
Cashew nut is a seed.[4]
-
Gevuinanut
-
Horse-chestnut is an inedible capsule.
-
Macadamia nut is a creamy white kernel (Macadamia integrifolia).
-
Malabar chestnut
-
Mongongo
-
Peanut is a legume.
-
Pine nut is the seed of several species of pine (coniferous
trees).
-
Pistachio nut is the seed of a thin-shelled drupe.
Nutritional benefits
A graph detailing the nutritional properties of nuts and oily
seeds.
Several epidemiological studies have revealed that people who
consume nuts regularly are less likely to suffer from coronary
heart disease (CHD).[5] Nuts were first linked to protection
against CHD in 1993.[6] Since then many 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 Omega
3 fatty acid profile is at least in part responsible for the
hypolipidemic response observed in clinical trials.[7]
In addition to possessing cardioprotective effects, nuts
generally have a very low glycemic index (GI).[8]
Consequently, dietitians frequently recommend nuts be included
in diets prescribed for patients with insulin resistance
problems such as diabetes mellitus type 2.[9]
One study found that people who eat nuts live two to three
years longer than those who do not.[10] However, this may be
because people who eat nuts tend to eat less junk food.[11]
Nuts contain the essential fatty acids linoleic and linolenic
acids, and the fats in nuts for the most part are unsaturated
fats, including monounsaturated fats.
Many nuts are good sources of vitamins E and B2 (riboflavin,
an antioxidant), and are rich in protein, folate, fiber, and
essential minerals such as magnesium, phosphorus, potassium,
copper, and selenium.[12]
Other uses
The nut of the horse-chestnut tree (Aesculus species,
especially Aesculus hippocastanum), is called a conker in the
British Isles. Conkers are inedible because they contain toxic
glucoside aesculin. They are used in a popular children's
game, known as conkers, where the nuts are threaded onto a
strong cord and then each contestant attempts to break their
opponent's conker by hitting it with their own. Horse
chestnuts are also popular slingshot ammunition.
Historical usage
Nuts were a major part of the human diet 780,000 years ago
including the wild almond, prickly water lily, acorns,
pistachio and water chestnut. Prehistoric humans developed an
assortment of tools to crack open nuts during the pleistocene
period.[13] Aesculus californica, was eaten by the Native
Americans of California during famines after the toxic
constituents were leached out.
See also
G-d Pharmacy: Rebbe Nachman of Breslev teaches us that
when we observe the Divine wisdom within G-d's creations, then
that wisdom will illuminate our souls and help us connect to
G-d. [A video presentation - a must watch]
* List of edible seeds
References
1. ^ Alasalvar, Cesarettin; Shahidi, Fereidoon. Tree Nuts:
Composition, Phytochemicals, and Health Effects (Nutraceutical
Science and Technology). CRC. p. 143. ISBN 978-0-8493-3735-2.
2. ^ Black, Michael H.; Halmer, Peter (2006). The encyclopedia
of seeds: science, technology and uses. Wallingford, UK: CABI.
p. 228. ISBN 978-0-85199-723-0.
3. ^ "Common Food Allergens". Food Allergy & Anaphylaxis
Network. http://www.foodallergy.org/allergens/index.html.
Retrieved 2007-06-24.
4. ^ Lina Sequeira. Certificate Biology 3. East African
Publishers. pp. 130–. ISBN 9789966253316. http://books.google.com/books?id=7AfHwKm8vu0C&pg=PA130.
Retrieved 29 July 2010.
5. ^ Kelly JH, Sabaté J (2006) Nuts and coronary heart
disease: an epidemiological perspective. Br J Nutr 96,
S61-S67.
6. ^ Sabaté J, Fraser GE, Burke K, Knutsen SF, Bennett H,
Linsted KD (1993) Effects of walnuts on serum lipid levels and
blood pressure in normal men. N Engl J Med 328, 603-607.
7. ^ Rajaram S, Hasso Haddad E, Mejia A, Sabaté J (2009)
Walnuts and fatty fish influence different serum lipid
fractions in normal to mildly hyperlipidemic individuals: a
randomized controlled study. Am J Clin Nutr 2009, 89,
1657S-1663S.
8. ^ David Mendosa (2002). "Revised International Table of
Glycemic Index (GI) and Glycemic Load (GL) Values". http://www.mendosa.com/gilists.htm.
Retrieved 2007-11-23.
9. ^ Josse AR, Kendall CWC, Augustin LSA, Ellis PR, Jenkins
DJA (2007) Almonds and postprandial glycemia — a dose response
study. Metabolism, 56, 400-404.
10. ^ Fraser GE, Shavlik DJ (2001) Ten years of life: Is it a
matter of choice? Arch Int Med, 161, 1645-1652.
11. ^ "ABC News: The Places Where People Live Longest". URL
accessed January 18, 2007.
12. ^ Kris-Etherton PM, Yu-Poth S, Sabaté J, Ratcliffe HE,
Zhao G, Etherton TD (1999) Nuts and their bioactive
constituents: effects on serum lipids and other factors that
affect disease risk. Am J Clin Nutr 70, 504S-511S.
13. ^ "Remains of seven types of edible nuts and nutcrackers
found at 780,000-year-old archaeological site".
Scienceblog.com. http://scienceblog.com/community/older/2002/F/20022752.html.
Retrieved 2010-09-13. |
