Peanut

The peanut plant is a low annual herb, about 30 to 50 centimetres high, with yellow pea-like flowers. After pollination a stalk called a peg bends down and pushes the developing ovary into the soil, where the pod matures. The pod is a netted, brittle shell, usually containing two seeds covered by a thin reddish-brown skin. The seeds are creamy white, with a mild, nutty taste that becomes stronger when roasted. Botanically peanuts are legumes related to beans and lentils, not true tree nuts. Varieties such as runner, Virginia, Spanish and Valencia differ in seed size and use.

Peanuts were domesticated in South America, probably in the region of northern Argentina and Bolivia, from wild species such as Arachis monticola and A. duranensis. The crop is grown in warm temperate and tropical areas around the world, with China, India, Nigeria, the United States and Sudan among the largest producers. It prefers light, sandy, well-drained soils and a long, warm growing season. Being a legume, it fixes nitrogen and is often used in crop rotation.

Archaeological finds in Peru show that peanuts were being eaten thousands of years ago, and the crop was widely grown in South America when Europeans arrived. Spanish and Portuguese traders carried it to Africa, Asia and Europe in the sixteenth century, where it quickly became established in local farming systems and cooking.

In the United States, peanuts spread with the slave trade, and were grown in the South. Their commercial use increased in the nineteenth century, and the agricultural scientist George Washington Carver promoted the crop for soil improvement and encouraged new products. Peanut butter became popular in the early twentieth century, and today peanuts are used worldwide in snacks, oil, sauces and confectionery. They are among the most important legume crops, and also among the leading causes of food allergy.

Peanuts are eaten boiled, roasted or fried, and ground into peanut butter. They are used in West African groundnut stews, Thai and Indonesian satay sauces, Indian chutneys and snacks, Chinese stir-fries and Southern United States boiled peanuts. Peanut oil is widely used for frying because of its high smoke point and mild taste. Peanut flour adds protein to baked goods, and peanut meal is used as animal feed. Raw peanuts should be roasted or boiled to improve flavour and digestibility.

Peanuts provide protein, unsaturated fat, fibre, niacin, folate, vitamin E and magnesium, and are a notable plant source of protein among nuts. Observational studies have linked regular nut and peanut intake with lower risk of heart disease, though these cannot prove cause and effect. Peanut butter without added sugar or hydrogenated oil is a better choice than sweetened varieties. As they are calorie-dense, a typical serving is a small handful or about two tablespoons of peanut butter.