Scientific name: Corylus spp
Common name: Hazelnut or hazelnut
Botanical family: Betulaceae
General characteristics: There are two main species of hazelnut being Corylus avellana which is found in the wild in Western Europe and England and Corylus maxima which is native to Southeast Europe and Western Asia. However, there are many hybrids of these two species that are difficult to be separated and all are known as hazelnut. In Turkey there is the native species Corylus colurna which forms trees up to 25 meters high which produces very large hazelnuts and which are commercially valued. There are species of Corylus native to Canada, China and Japan with much smaller fruit than the European species, but also very important as food throughout human history. The American Corylus species, native to North America, produces long fruits with hard shell and smaller than the other hazelnut species. In decreasing order of importance, the largest world producers are: Turkey, Italy, USA, Azerbaijan, Georgia, Iran, China and Spain. The hazelnut fruits are produced in bunches with 1 to 10 fruits that release the hazelnuts (seeds) when the casings dry and open.
The hazelnuts are smooth and brown when ripe and have a hard and shiny shell which is the pericarp, in which is inserted a single seed which is the edible part of the hazelnut. There is a variation in shape of the hazelnut from round, oval to oblong.
A hazelnut produces from 6 to 12 kg of hazelnuts per year depending on the weather conditions, cultivation and cultivar. The trees in production tend to alternate the production every 2 or 3 years and, in this way, pruning of new branches and the removal of new fruits should be done. Besides this, the fruits that remained on the tree should be removed so that there is no inhibition in the formation of new female flowers.
The harvest is done in autumn, through the collection of fruit on the ground, which open naturally. The hazelnuts must be dried so that the moisture content is around 12%, reducing the risk of contamination by aflatoxin. Hazelnuts can be stored in dry and cold conditions for 5 months and, if placed in a refrigerator, they can remain in good condition for one year or two years in a freezer.
Uses: Hazelnuts can be used in various ways in desserts or salads, eaten raw or toasted as an aperitif, along with cereals and all kinds of preparations where nuts or chestnuts are used. It can be ground to make a flour added to bread, to which they confer delicious aroma and taste. In addition to food use, hazelnuts are planted in several countries for ornamental purposes forming living fences with colorful foliage and twisted branches.

Source: DONADIO, L.C.; ZACCARO, R.P. Fruit nutritional value
Hazelnut has a very large nutritional value, containing high concentration of vitamin E, around 60% of oils, being 55% monounsaturated as oleic acid, 15% polyunsaturated as linoleic acid and omega 6, 25% of other polyunsaturated oils and around 5% saturated oils. Hazelnuts present a higher concentration of oleic acid than olive.
Studies showed that consumption of 25 grams of hazelnuts per day for 16 weeks resulted in a 2 to 10% reduction in LDL cholesterol in a group ranging from children to adults that was compared to a group that did not consume hazelnuts. It also contains a high concentration of calcium (200 mg/100g of fruits) with high levels of magnesium, potassium, thiamine and folic acid besides iron, copper, manganese and 13% protein.
Vitamins – The hazelnut seed has in average 250 IU of vitamin A; 460 mcg of B1; 550 mcg of B2; 5,000 mg of B3 and only 7 mg of vitamin C.
Minerals (in 100 g of fruits) – Calcium – 113 mg; iron – 4,6 mg; magnesium – 162 mg; phosphorus – 289 mg; potassium – 681 mg, selenium – 2,4 mg.
Other average data of hazelnut indicate, besides its high caloric value, some vitamins and folic acid, with medicinal value. Despite its high fat content, most of them are unsaturated. Only 15 to 20 hazelnuts contain nutrients equivalent to a meal. It is recommended to chew them well when eating, to facilitate their digestion.
From the American hazelnut is obtained a very nutritious paste used in cooking, also with high oil content.

ADDITIONAL INFORMATION
Also called European hazelnut, because there are other types of hazelnut, it is famous in other languages: hazelnut in English; nocciola in Italian; and avellano in Spanish. Its oil has medicinal use, rich in polyphenols and flavonoids. The skin of its fruit is bitter and therefore should be removed when used in cooking or natural food. The best known hazelnut-based product is praline, which is hazelnut combined with chocolate. The fruit also provides the hazelnut milk, which is the kneaded fruit, to which water is added, sweetened with honey. There is also a very popular liqueur in the producing countries.
DONADIO, L.C. and others; Exotic Fruits, 1998.