A nut is strictly a dried tree fruit inside a hard shell, though the term is commonly used to refer to any type of kernel in a hard shell.
The humble peanut, for instance, is not a true nut, but a legume, while almonds, cashews, and Brazil nuts are all strictly seeds — the embryo and food store for a new plant.
Most nuts are highly concentrated sources of nutrients, containing fat, protein and carbohydrate as well as many vitamins and minerals. The levels of the various nutrients fluctuate widely from species to species.
Pine nuts, for instance, and pistachios, contain about 50 percent fat, while the chestnut has very little fat and proportionately more carbohydrate.
Many nuts have been cultivated by humans for thousands of years. The Romans cultivated nuts at the time of Christ. Hazelnuts were eaten in China as long ago as 3000 BC, and peanuts were eaten in Peru almost 3000 years ago. The pistachio has been cultivated in Asia and the Middle East for thousands of years.
Nuts are sold in many forms: shelled or unshelled, roasted or raw, blanched or with their thin, inner skins intact.
If you are buying nuts in the shell, look for shells that are free of cracks and holes, and watch out for signs of mold. If you are buying shelled nuts go for ones of the same size and color and reject any which appear to be soft or shriveled.
Most nuts, except those like chestnuts which have a high water content, can be safely stored for months in a cool, dry cupboard. They will keep even longer if refrigerated, and most nuts can be frozen.
The most common kinds of nuts sold in the US are:
The cashew is grown mostly in India and Africa. The cashew plant is related to poison ivy, and the shell of the cashew itself is toxic and is used in industrial products ranging from insecticides to rocket lubricants and paint. Cashews are generally eaten roasted or raw. They are also widely used in vegetable or chicken dishes.
There are two varieties of almond: bitter and sweet. Bitter almonds are made into the essence, while sweet ones are marketed either in the shell or shelled and prepared in many ways.
They can be bought blanched, slivered, flaked, ground into meal or mixed into a paste. Almonds are a good source of calcium and monounsaturated fat. They feature in many sweet and savory dishes, notably in confectionery (nougat and marzipan) and desserts.
Brazil nut is one of the most nutritious nuts. It is a good source of vitamin E, phosphorus, magnesium and dietary fiber, among other things.
Brazil nuts originated in South America, where they grow in large pods that can weigh up to 2kg. They are generally eaten whole (the smaller specimens, at least).
The walnut is one of the most popular nuts in the world. Most are grown in the United States, Italy and France, although varieties are also native to parts of Asia.
Ripe walnuts slip surprisingly easily from their convoluted shells, and are sold whole, halved, or crushed. Walnuts can be picked while green and pickled. They are commonly eaten by themselves, or in confectionery and salads. Walnut oil is a highly prized cooking oil.
The pistachio is an ancient nut, originating in Asia and the Middle East. The shells split open when the nut is ripe, revealing a nut with a greenish flesh and a distinctive flavor. They are often salted while still in the shell and sold in that form. The pistachio is also a popular ingredient in ice cream and meat dishes.
This nut grows on a tree that is a member of the hickory family. It has a softer texture than most nuts but becomes quite crisp when toasted.
The most famous dish containing the nut is the pecan pie, an American institution, featuring a rich shortcrust pastry with pecans in a rich, caramel filling.
The peanut grows underground on a legume bush which is native to South America. It is also known as groundnut in some parts of the world. Peanut oil is an important cooking oil in many parts of the world.
Peanuts are sold raw, in the shell, shelled, roasted, salted and crushed. They are also ground to make peanut butter. Peanuts are high in protein and fat and are a good source of niacin, folacin, pantothenic acid and vitamin E.
Pine nuts are seeds from the cones of many varieties of the pine tree. They are popular in Spanish and Italian cuisines and have a delicate but distinctive flavor.
Pine nuts are an ingredient in pesto sauce and are commonly used in stuffings and salads. They are almost invariably sold shelled and are more expensive by weight than many other nuts.
The hazelnut is often sold ground, for use in desserts and cakes, but it is also a popular inclusion in mixed-nut selections. Hazelnuts have less fat and protein than some other nuts and are a particularly good source of vitamin E.
The macadamia is an Australian native that has become extremely fashionable in recent years. It is a delicious, oily nut with a mild flavor.
There are two varieties of macadamia, one with a rough shell and one with a smooth. Both shells are practically impenetrable, so most macadamias are shelled commercially and sold roasted and salted.
Nuts are too commonly seen as a snack food in our culture. Give them space on the table in a variety of dishes, to experience their full potential.