The hazelnut, cobnut or filbert is the fruit of the hazel tree, Corylus avellana L. (Family Betulaceae) and is a true nut.Hazelnut is a native of Britain and of all the temperate parts of Europe and Asia. The Hazelnut is referred to as the filbert in North America where it was first grown in the mid 1800's.
It is roughly spherical, about 10 to 15 mm in diameter, with an outer fibrous husk surrounding a smooth shell.
The husk falls off during ripening. The kernel of the seed is edible and used raw or roasted, or ground into a paste. The seed has a thin, dark brown skin which has a bitter flavour and is sometimes removed before cooking.
Hazelnuts are produced in southern Europe and in the American states of Oregon and Washington.
Hazelnut oil, pressed from hazelnuts, is strongly flavoured and used as a cooking oil. Hazelnut oil is used in salads and cooking, and commands high prices. During the 19thcentury, hazelnut oil was used by painters because of it's excellent drying properties. It was also used by perfumers and has been employed medically to treat coughs and colds.
Hazelnuts are extensively used in confectionery to make praline and also used in combination with chocolate for chocolate truffles and products such as Nutella.