Apricot kernel

The apricot is a small deciduous tree, three to twelve metres tall, with white-pink spring blossom and round, velvety orange fruit. Inside each fruit is a smooth, flattened, oval stone, and inside the stone sits a single almond-shaped kernel about 1.5 to 2 cm long, covered with a thin brown skin.

Sweet-type kernels taste mild and nutty and slightly like almond, while bitter-type kernels taste strongly bitter and marzipan-like. They are sold raw, roasted, as oil, as kernel flour and as flavouring for liqueurs such as amaretto and noyau, and they are used in baking in the Mediterranean and Central Asia. Sellers should state whether a product is sweet or bitter.

The apricot is believed to have been domesticated in Central Asia or China, with wild populations in the mountains from Central Asia to northern China. It was carried along trade routes to Persia, Armenia and the Mediterranean, and the species name armeniaca reflects an old Roman belief that the tree came from Armenia.

The English word apricot comes through French and Spanish and Arabic from Latin praecoquum, meaning early ripening. In Central Asian and Himalayan villages, kernels have long been eaten and pressed, with some communities, notably in the Hunza valley of Pakistan, known for using the oil.

Apricot growers on the Silk Road valued the kernel as well as the fruit. In the high valleys of Hunza and Ladakh, villagers dried the fruit for winter and used the kernels for oil and as a snack, and in China the bitter kernel, xing ren, is a long-standing ingredient in traditional medicine formulas for cough, listed in classical pharmacopoeias. Sweet kernels feature in Chinese dishes and the soft drink-like almond tea used in northern China.

In Europe, apricot kernels flavoured liqueurs and sweets, including Italian amaretti biscuits, which were traditionally made from bitter apricot or almond kernels, and French noyau liqueur. Both uses rely on benzaldehyde, the compound that gives the marzipan aroma.

In the 20th century, amygdalin was marketed as laetrile, or vitamin B17, as an alternative cancer treatment, and apricot kernels were promoted for the same purpose. Clinical trials found no benefit and documented cyanide poisoning, and the claim has been rejected by cancer organisations and health regulators. Food safety agencies in Europe and elsewhere have since advised limits on raw bitter kernel consumption, and some countries restrict their sale as food.

Sweet kernels are eaten like almonds, ground into baked goods and sweet pastes, and pressed for edible oil. Bitter kernels, after proper processing to reduce amygdalin, flavour amaretti, liqueurs and marzipan-like confections, and are used in traditional Chinese herbal formulas. Kernel oil is also used in cosmetics and massage.

The shells are made into activated carbon and fuel, and ground kernels have been used as livestock feed after detoxification. Sweet-kernel varieties are also grown especially for the snack trade, and the roasted kernels are cracked at home in Turkey, Iran and Central Asia.

Apricot kernels contain fat, protein and fibre, and sweet kernels have been a traditional food. Bitter kernels have no proven medical use. Amygdalin and laetrile have been tested as cancer treatments, and the evidence shows no benefit and a real risk of cyanide poisoning. Anyone considering kernels for health reasons should rely on guidance from a qualified clinician rather than marketing claims.