The walnut (Juglans regia L.) is native to Western Asia but was also found in southern Europe early on. Since ancient times its leaves, fruit husk, nut, and the oil of its kernel have been used for medicinal and culinary purposes. Walnuts were primarily eaten for dessert by the ancient Greeks and Romans, who called them ‘Persian nuts’. It was not known in ancient Egypt and only arrived there during the Ptolemaic period (from Persia). The Arabic word for ‘walnut’, جوز (jawz) is a borrowing from the Persian گوز (gawz).
In the medieval Arab culinary tradition, the leaves, shells, nut (both cooked and dried) and oil from the pit were used. Walnuts combined with a souring agent (for instance, vinegar, pomegranate juice, sumac) are often found in recipes for condiments to accompany meat or fish dishes, whereas green walnuts were favoured for pickling. Walnut oil was often used uncooked and poured on sweets before serving, as in the case of an Abbasid qatayif (قطائف). Walnuts were also used to remove the bad odour of meat that has gone off by hanging two whole ones in the pot after piercing the shells. The bad smell would allegedly be fully absorbed by the nuts. Walnuts were the base of a very popular confection, known as jawzīnaq (جوزينق) or jawzīnaj (جوزينج), which was Persian in origin and is already mentioned in a sixth-century Sasanian text, alongside a variant made with almonds (لوز, lawz) and known as lawzīnaq/j (لوزينق, لوزينج).
Muslim physicians concurred with Dioscorides that walnuts were difficult to digest (the dried ones more than the fresh green ones), harmful to the stomach and to cause pustules in the mouth. As a result, they should be mixed with honey, combined with other substances such as rue or onions. Roasted walnut shells were also used to dye the hair black. It was thought that walnuts eaten with figs and oxymel (a mixture of vinegar and honey) served as an antidote to poisons.
The illustration below of walnuts in the herbal compiled by the Andalusian scholar al-Ghafiqi (12th century) also lists their alternative name qārūdhiyā bāsilīqā (قاروذيا باسليقا), a variation of the more usual qāruwā bāsilīqā (قاروا باسليقا), from the Greek κάρυα βασιλικά, meaning ‘royal nut’.
