Raisin is a dried grape. The word raisin comes from a French term meaning dry grape. Varieties of white grapes that have tender skin, rich flavor, and high sugar content are especially suited for making raisins. Raisins are used in puddings, cakes, candies, cookies, and bread. They are also sold as sweets in small boxes.
Raisins have been a food delicacy since ancient times. The Egyptians first discovered that drying fruit preserved it, made it sweeter, and improved its flavor. The Bible mentions that an Israelite brought cheese and raisins to pay his taxes to King David. Wealthy Romans served raisins at feasts.
Spanish missionaries planted grapevines in California during the 1700’s. Soon after the Civil War ended in 1865, former gold hunters discovered that the region of California now called the Central Valley had an ideal climate for producing raisins. The dry, hot summers allowed for grapes to ripen, and the low chance of rain after the harvest meant that the grapes could be sun-dried in the vineyard. Commercial raisin production began in California in the 1870’s.
Today, California leads the world in raisin grape production. It is the only U.S. state that produces raisins commercially. California produces about 670 million pounds (300 million kilograms) annually. Other leading producers include Australia, Greece, Iran, and Turkey.
Varieties of raisins.
Four main varieties of grapes are used in raisin production. The most common is the Thompson Seedless. Seedless grapes used to make raisins first came from Turkey. In 1872, William Thompson introduced seedless grape cuttings to California. Thompson Seedless today make up more than 95 per cent of the grapes used to make raisins in California. Other varieties include Muscat of Alexandria, Black Corinth, and Sultana. The Muscat is a large, seed-bearing grape brought to America by Spanish missionaries. Grapes from Black Corinth vines are used to make Zante currants–tiny, seedless raisins used mainly to flavor baked goods. Raisins made from Sultana grapes, which are seedless and have a distinctive flavor, are used mainly in baked goods.
Growing grapes.
Almost all the raisins produced in California come from vines grown within 100 miles (160 kilometers) of Fresno. Grapevines start growing there in March, and the fruit is harvested about the first week of September. The vineyards must be irrigated because little rain falls in the area during the period when the vines grow. Vines used for raisins generally are planted in rows that run in an east-west direction. They must be spaced far enough apart to allow room for drying the fruit and to permit cultivation. Grapevines begin bearing fruit in three years. With proper care, they may continue to produce fruit for 100 years. About 41/2 pounds (2 kilograms) of grapes produce 1 pound (0.5 kilogram) of raisins.
Preparation for market.
Seedless grapes ripen on the vine until sugars account for more than 20 per cent of their weight. The grapes are then harvested by hand or machine and placed on trays of heavy, brown paper between the rows of vines. The fruit may be turned over after about eight days so that grapes on the bottom can dry faster. The east-west direction of the rows allows the sun to dry the grapes in 10 to 14 days. The raisins are then stored in large bins, called sweat boxes, to equalize their moisture content. Next, the fruit is sent to packing houses, where workers stem and grade the raisins by passing them over screens. Machines remove stem caps. A machine whirls the raisins through a fine spray of water to give them a final cleaning. The raisins are then pressed into sealed packages.
Raisins with seeds go through a slightly different process. Muscat raisins are larger and softer than the seedless types after drying. They are passed through the stem-removal machine and are washed in hot water to soften them further. They are then fed between rubber rollers that press the seeds to the surface. A saw-tooth roller catches the seeds between its teeth and removes them.
Sun-dried raisins are called natural raisins. Most raisins are natural. However, golden seedless or golden raisins, made from Thompson Seedless grapes, are dried in large machines. The grapes are first treated with sulfur dioxide to preserve their golden color.
Because of their high sugar content, raisins need no preservatives to keep them fresh. If raisins are kept cool and stored in a sealed container, they will retain their flavor, color, and nutritional value for up to 15 months. They may also be frozen.
Food value.
Raisins are a good source of vitamin A, the B-1 vitamins thiamine and riboflavin; and such minerals as calcium, iron, and potassium. The sugars in raisins give quick energy because the body absorbs them immediately.
