Sultana is a word with several different, but related, meanings depending on the part of the world in which it is used. Its broadest usage is that of a colloquial name for a certain type of grape, the green Thompson seedless. It is sometimes associated with other similar grapes, or raisins, particularly golden raisins.
The Thompson seedless grape is a green grape and one of the world's most common and versatile varieties. It is used for table fare, winemaking, and drying into raisins and is believed to originate from an ancient variety of green grape, historically called the sultana grape. It was native to the Asia minor region, the area that is now Turkey, or, perhaps, modern day Iran. Today, it is still called the sultana grape in some regions, or occasionally the sultanina.
The usage of the term sultana can vary and sometimes lead to confusion. Generally, "sultana" refers to the golden raisins that are most often made from Thompson seedless grapes. Other varieties of grape may be used as well, and these golden raisins are often called sultanas. In some areas of the world, such as Australia, all raisins are called sultanas. For example, the popular American breakfast cereal, Raisin Bran, is called Sultana Bran in Australia.
Golden and regular raisins can both be made from Thompson seedless grapes. The difference in color is due to the treatment of the raisins, which, in the case of the golden raisins, can be a product of one of two processes. The raisins that are called sultanas are subjected to a much faster drying process process, which helps them retain their lighter color. This process involves soaking the grapes in a solution of oil, water, and potash before drying. Alternatively, they may be treated with sulfur dioxide to achieve the same effect.
When regular raisins are made from Thompson seedless grapes, they are usually not called sultanas, distinguishing them from the golden variety. This distinction is common only in North America, however. To further add to the confusion created by the varying usage of the term, in the United States, the names "Thompson seedless grape" and "sultana" are defined by the US Federal Code of Regulations as having the same meaning, which means that legally, in the United States, the term sultana means "grape" even though it is rarely used that way in that country.