Some 2,500 varieties of apples are grown in the United States, and the popular fruit is grown commercially in 36 states. The top apple-producing states are Washington, New York, Michigan, California, Pennsylvania and Virginia, and many orchards allow customers to pick their own apples during peak season in the fall. Here's how to find the tastiest fruits and keep them that way after picking.

Picking tips:

• Select firm, bruise-free apples. Remember, color can vary widely depending on the apple's variety, so don't depend on color alone to tell you whether the fruit is ripe. Apples come in hues ranging from dark green to yellow, as well as pink, orange, bright red, dark red and even combinations of color.
• Apples on outside branches of the tree ripen first, with those towards the center of the tree ripening last.
• Ask questions! The orchard staff will know which trees have ripe fruit because ripening dates are calculated from the number of days since the trees flowered. The staff can also tell you what characteristics to look for in the particular varieties being grown.

Storage tips:

• When you are picking apples, don't throw them into containers. Place them gently, or they will bruise and go bad more quickly.
• Don't wash apples until just before use to prevent spoilage.
• Keep apples cool after picking to increase shelf life. A cool basement is ideal, but the fruit/vegetable drawer of a refrigerator will work as well. Fresh-picked apples will generally keep for weeks, but the variety makes a difference. For instance, Red Delicious apples do not keep well.
• High humidity will help keep your apples from shriveling, but don't let the apples themselves get wet. A wet towel placed nearby helps to keep humidity high.
• A refrigerator is fine for small quantities of apples, but a box of apples should be kept in a cool, dark spot where they won't freeze. Freezing ruptures all of an apple's cells, turning it into one large bruise.
• Apples and potatoes should never be stored together. As they age, potatoes release ethylene gas, which makes apples spoil faster.
• Prevent contact between apples stored for the winter by wrapping them individually in sheets of newspaper.

Apples are a healthful snack: they contain no fat or cholesterol, and 1/2 cup of apples has only 42 calories. Apples are high in dietary fiber, vitamin A and niacin. They contain iron and other trace minerals and some vitamin C as well.