Apples that are not to be eaten immediately must be kept cold to preserve maximum freshness. Apples deteriorate 10 times as fast without proper refrigeration.
Preparing Apples For Freezing
Enzymes in light colored fruits such as apples, pears and peaches can cause oxidative browning as soon as the fruit is peeled or cut. Browning can cause loss of vitamin C. Because fruits are usually served raw they are not usually blanched to prevent this discoloration. Instead, chemical compounds are used to control enzymes in these fruits.
The most common treatment is ascorbic acid (vitamin C). Ascorbic acid may be used in its pure form or in commercial mixtures of ascorbic acid and other compounds. Browning can also be halted temporarily by placing fruit in citric acid or lemon juice solutions or in sugar syrup. However, these measures are not as effective as treatment with ascorbic acid in its pure form.
Apples retain better texture and flavor if packed in sugar or sugar syrup. However, sugar is not necessary to safely preserve fruit. Fruits packed in syrup are generally best used for uncooked desserts. Those packed in syrup or unsweetened are best for most cooking purposes, because there is less liquid in the product.
Freezing Apples In Syrup
This syrup recipe will make 5 1/3 cups syrup which will cover approximately 6 pints or 3 quarts of apple slices. Use rigid freezer containers or zip-closure freezer bags.
2 ½ cups sugar
4 cups water
3 pounds apples
½ teaspoon ascorbic acid powder (1500 mg)*
To make syrup, dissolve sugar in lukewarm water, mixing until the solution is clear. To prevent browning add ½ teaspoon ascorbic acid powder or equivalent in finely crushed vitamin C tablets. Stir to dissolve. Chill syrup before using.
Select fresh full-flavored apples that are crisp and firm, not mealy in texture. Wash, peel and core. Slice medium apples into twelfths and large apples into sixteenths. Place ½ cup syrup in each pint-size container and slice each apple directly into chilled syrup. Press apples down in containers and add enough syrup to cover apple slices. Leave ½ inch headspace in each pint (or 1 inch in each quart-size container). Place a small piece of crumpled water-resistant paper, such as waxed paper, on top of each container to hold apple slices down under syrup.
Seal, label, date and freeze at 0°F or below. Use within one year.
*To use lemon juice: drop apple slices into a solution of two tablespoons lemon juice and two quarts water. Drain well before covering with syrup.
Freezing Apples Without Sugar
Apples frozen without sugar are generally used for cooking. They can be used for pie making too!
Wash, peel and core apples. To prevent darkening, dissolve ½ teaspoon (1500 mg) ascorbic acid powder or equivalent of finely crushed vitamin C tablets in 3 tablespoons water. Sprinkle over apples. Place apple slices in zip-closure freezer bags; label, date and freeze. Treated apples can always be frozen first on a tray leaving space between each piece. Pack into containers as soon as slices are frozen (approximately 2-4 hours). Freeze for up to one year at 0°F or below.
Dry Sugar Packed Apple Slices
Follow directions for "Freezing Apples Without Sugar"; mix ½ cup sugar to each quart apple slices. Place apples in containers and press fruit down, leaving ½ inch headspace for pints and quarts. Seal and freeze for up to one year at 0°F or below.
Preventing Discoloration In Canning
After they are cut or peeled, apples will begin to turn dark due to oxidation. To prevent this as you prepare the fruit for canning or cooking, place in a holding solution made from ascorbic acid or vitamin C tablets. Tablets contain filler, which may turn the water cloudy, but it is not harmful.
Ascorbic acid powder can be purchased at health food stores or drug stores. It prevents darkening while enhancing nutritional value of apple recipes, and without changing flavor. Commercial ascorbic acid mixtures can also be used. Read the label on the container for the amount to use. Although lemon juice adds slight lemon flavor and may not be as effective, bottled or fresh lemon juice can also be used at a ratio of ½ cup per ½ gallon water.
Source: So Easy to Preserve, Fourth Edition, University of Georgia Cooperative Extension Service
Prepared by: Drusilla Banks, Extension Educator, Nutrition and Wellness, University of Illinois Extension