Laurie Drummond, age 11, of Yarmouth, Me., for her question:
HOW CAN SWEET RAISINS BE MADE FROM SOUR GRAPES?
Four types of grapes are used for making raisins, with muscats and Thompson seedless grapes the most common. Sultana seedless grapes also are used, as are Corinthians. The Corinthian is also known as a current. A man named Thompson brought the first seedless grapes to California in 1879, and the other varieties were introduced during mission times by priests.
A sun dried grape is a raisin. Popular since the days of the ancient Egyptians, raisins are a food delicacy that can be eaten plain and used in cookies, cakes and candies.
Sometimes the grapes may be sour when they are fresh and just off the vine but drying the fruit preserves it, makes it sweeter and improves its flavor. All varieties of grapes used for raisins are noted for their rich flavor and high sugar content.
To turn a grape into a raisin, you start by allowing the grapes to ripen on the vine. Then they are harvested either by hand or by machine and placed on sheets of heavy brown paper rolled out between the rows of grapevines. After drying them in the sun from between 10 and 15 days, the seedless raisins are stacked and dried again. From here they go to great bins called sweat boxes where their moisture content is equalized.
Next step for the raisin is the packing house where workers remove stems and pass the fruit over screens.of different sized mesh. Machines remove the stem caps as the raisins pass between revolving screens. Another machine whirls them through a fine spray of water and gives them a final cleaning. Then by machine the raisins are pressed and sealed into packages.
Muscat raisins with seeds receive more drying time than do the seedless variety. After drying, they are softened again with a hot water washing. Next they are fed between rubber rollers which press the seeds to the surface. A saw toothed roller catches the seeds between its teeth and removed them. The seeds are then carried away while the raisins advance to a machine that packages them.
Raisins are well known as a nourishing food. Moisture makes up 24 percent, with 71.2 percent being carbohydrates. Two percent ash, .5 percent fat and 2.3 percent protein complete the nutrition countdown. Ten minerals of important food value are also included.
California is the only state that produces raisins commercially. Its central valleys with hot, dry summers and mild winters provide ideal weather to grow the grapes necessary to produce raisins.
As early as 1892, California was growing more raisins than Spain, the longtime top producer. Each year California produces about 350 million pounds of raisins.