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Inbotany, ahusk (orhull) is the outer shell or coating of aseed. In the United States, the term husk often refers to the leafy outer covering of anear ofmaize (corn) as it grows on the plant. Literally, a husk or hull includes the protective outer covering of a seed,fruit, orvegetable.
It can also refer to theexuvia of insects or other small animals left behind aftermoulting.
The termhusk dates to c.14, it is probably based onMiddle Dutch wordhuusken meaning 'little house', which is derived fromhūs meaning house.[1]
Incooking,hull can also refer to other waste parts of fruits and vegetables, notably the cap orsepal of astrawberry.[2]
Grains such aswheat andbarley have husks. The grains are the entire seed of a plant. The seed of a grain (which the grain industry calls a "kernel") is made up of three key edible parts – thebran, thegerm, and theendosperm – which are all protected by an inedible husk that protects the kernel from damage by sunlight, pests, water and disease.[3]
InHazel trees, the nut is surrounded by a short leafy husk (which is technically aninvolucre). This leaf-like husk encloses most of the nut. It starts off green and will fade to brown at the end of the season. Usually, the ripe nut falls out of (or can be separated from) the husk some 7–8 months afterpollination has occurred.[4]
In some places, both shells and the husks of walnuts (Juglans regiaL.) which are produced as waste crops during the fruit harvesting and processing,[5] are sometimes burned as fuel for heating purposes.[6] In 2019, it has been demonstrated that the walnut green husk could be valued as a source of different natural bio-active compounds with excellentantioxidant andantimicrobial properties.[7][8] As well as cosmetic uses.[9] An organic compound Naphthalenone, (derivative ofNaphthalene) is found in green walnut husks ofJuglans mandshuricaMaxim. for various uses.[10]Juglans nigra, black walnut, husks have antioxidant potential.[11]Confusingly, Walnut husks are also calledhulls as well.[12][13]Rhagoletis juglandis, also known as the 'walnut husk fly' is a common pest of walnuts. The larvae are small and live under the surface of the husk of the walnut. They cause damage to the fruit and husks which then become difficult to remove. The husk fly also infests ripeapricot andpeach fruits, usually if infested walnuts are located within flying distance.[14]
Some fruit shell and hull derivedbio-adsorbents have also been used forwastewater treatment purposes. For example, thealmond hull and shell have been used to remove metals such asPb,Cd, andCo in various quantities.[15] Iranian almond (Prunus amygdalusL.) hulls have antioxidant and anti-radical properties.[16]
Thecoconut husk and shells can be used for fuel and are a source ofcharcoal.[17] In Thailand, the coconut husk is used as a potting medium to produce healthy forest treesaplings. A dried half coconut shell with husk can be used to buff floors. It is known as abunot in the Philippines and simply a "coconut brush" inJamaica.Coir, also calledcoconut fibre, is anatural fibre extracted from the outer husk of coconut.[18]

Husking of corn is the process of removing its outer layers, leaving only thecob or seed rack of the corn. Dehulling is the process of removing the hulls (orchaff) frombeans and otherseeds. This is sometimes done using a machine known as ahuller. To prepare the seeds to haveoils extracted from them, they are cleaned to remove any foreign objects. Next, the seeds have their hulls, or outer coverings, or husk, removed. There are three different types of dehulling systems that can be used to processsoybeans: Hot dehulling, warm dehulling and cold dehulling. Hot dehulling is the system offered in areas where beans are processed directly from the field. Warm dehulling is often used by processors who import their soybeans. Cold dehulling is used in plants that have existing drying and conditioning equipment, but need to add dehulling equipment to produce high protein meal. The different dehullingtemperature options are for different types of production, beans and preparation equipment.[citation needed][19]

In third-world countries, husking and dehulling is still often done by hand using a largemortar and pestle. These are usually made of wood, and operated by one or more people.[20]
The husk isbiodegradable and may becomposted.[21]