Citrus are acidic fruit with a thick rind. Inside they have pulpy flesh divided into sections. Some are sweet, some are very sour.
The fruit is valued above all other fruits for their juices. The juices have both health benefits, being rich in Vitamin C, and cooking benefits: the acidity of the juices makes other ingredients taste fresher. The peel of Citrus Fruit is very high in pectin, and is used as a source of commercial pectin. The peel can also be used in candied fruit mixtures.
The sour ones, such as lemons, limes and bitter oranges, can basically be swapped for each other in recipes. Though the flavour of course will be somewhat different, they will still have the same souring and refreshing effect.
Generally, store at room temperature, but refrigerate if planning to store for over a week. Can be shipped waxed or unwaxed; waxing makes them seem a bit more shiny and appealing, but also preserves shelf life by keeping moisture in.
Citrus Fruit originated in South-Eastern Asia, perhaps Malaysia. By 4000 BC, they were in the Middle East.
The Egyptians did not have Citrus Fruits until after the Roman conquest, when the Romans introduced them. An early form of oranges is depicted on Constantine’s mausoleum. Citrus fruits disappeared from most of Europe after the fall of Rome, until reintroduced by the Arabs in Spain in 900 AD. According to local beliefs, however, some citrus remained in pockets of Southern Italy.
Citron was the first Citrus Fruit.