How to freeze fruit for best quality

It’s harvest time in Ohio for fresh fruit, and for those of us who grow our own fruit that could be more than we can enjoy in the short window of its shelf life. Sharing with friends and family is one option. Freezing extra fruit and storing it to use up over time is another.

Freezing fruit is an easy way to preserve fruit so that it retains its nutritional quality.

Ensuring success

Although the nutritional value of fruit is maintained when frozen, its color, structure and taste can be impacted by enzyme activity, air, microorganisms, the formation of ice crystals and the rate of moisture evaporation.

Enzyme activity. Enzymes naturally occur within fruits, regulating the ripening process. Freezing fruits slows this process, but doesn’t stop it. Ascorbic acid can be used to control enzyme activity and prevent browning when freezing fruit.

Air. Exposure to air can increase enzyme reactions and oxidation that cause surface browning. It can also increase moisture loss. Make sure air is removed and packaging is tightly sealed before freezing fruit.

Microorganisms. Bacteria, molds and yeast are present in all fresh foods and multiply rapidly when the temperature is between 40 F and 140 F. Freezing controls the growth of microorganisms; however, survivors can start growing again when food is thawed. This is why it’s important to freeze and thaw fruit properly.

Ice crystals. Small ice crystals are desirable because the texture of the fruit is preserved much better. Large crystals damage food cells and create a soft mushy texture. You can ensure the formation of small crystals by freezing food quickly and uniformly. Fruits with high moisture content such as berries and grapes can be frozen individually on cookie sheets for 4-6 hours and then put in storage containers. For fruits already packed in containers, make sure there is adequate spacing in your freezer so that cold air can circulate on all sides. Don’t overcrowd your freezer and space the food you are freezing out among the food that is already frozen to freeze efficiently.

Evaporation of moisture. Reducing the amount of moisture that evaporates from fruit while it is in the freezer means packing it correctly. Moisture loss leaves fruit exposed to oxygen, which results in loss of color, flavor and texture. As much air as possible should be removed from containers and freezer bags before sealing them and the correct amount of headspace should be left.

Headspace

• Fruits packed in juice, sugar, syrup or water and crushed and pureed fruit should have ½-¾ inch space for pint containers and 1- 1 ½ inch of space for quart containers. It’s important to leave enough space for liquid to expand so juices don’t overflow from your containers while freezing. Place a piece of plastic wrap on top of the fruit to keep it submerged in the syrup or liquid.
• Fruits packed without added sugar or liquid should have ½ inch of headspace.

Packing with sugar or syrup

Fruit can be frozen without sugar, however, it will freeze harder and take longer to thaw. Sugar helps keep frozen fruit firm and prevents browning.

Sugar. Fruits intended for pies and other baked products are often packed in sugar. One cup of sugar should be used for every 2-3 pounds of fruit. Juice will form as the fruit sits in the sugar. When using fruit packed with sugar in baking recipes, the relative amount of sugar added should be factored into the total sugar the recipe requires.

Syrup. Fruit that you’re preserving to be served uncooked can be packed in a syrup made of sugar and water. Honey and maple syrup can be substituted for a portion of the sugar, however, the flavor of the finished product may be affected. Use about ½ to ⅔ a cup of syrup for each pint of fruit and 1 ⅓ cups for each quart of fruit. Make sure fruit is covered in syrup before storing. Allow syrup to cool before pouring over fruit.

• Very light syrup: 4 cups water, ½ cup sugar
• Light syrup: 4 cups water, 1 cup sugar
• Medium syrup: 4 cups water, 1 ¾ cups sugar
• Heavy syrup: 4 cups water, 2 ¾  cups sugar
• Very heavy syrup: 4 cups water, 4 cups sugar

Other options. Water, fruit juice and pectin syrup can also be used to freeze fruit, however, they will not have all the benefits of freezing fruit using sugar or syrup. Juice has some of the benefits of freezing fruit with sugar and pectin power can be used to improve the frozen quality of fruits that have poor texture when frozen.

Freezing tips

• Choose fruits that freeze well. Right now, apples, blackberries, blueberries, cantaloupe, grapes, peaches, pears and plums are in season in Ohio.
• Prepare only a few containers to be frozen at a time, so that fruit can be frozen quickly and uniformly after it’s packaged and sealed.
• Wash fruit before packaging to remove any dirt, however, don’t let fruit soak in water.
• Don’t use galvanized copper or iron equipment to prepare fruits for freezing. The acid contained in fruit can react with the metals and form harmful compounds or change the flavor of the fruit.
• Remove green and bruised spots from fruit before freezing.
• Pretreat fruit to prevent browning by adding ascorbic acid to holding water to prevent browning. Use 1 teaspoon (3,000 milligrams) per gallon of water. The drain fruit before sweetening or packaging.
• Ascorbic acid can also be added to individual packs of fruit at a rate of ½ teaspoon per quart of cold syrup or ½ teaspoon in 3 tablespoons of cold water per 4 cups of fruit to be stored without syrup.
• Cool fruit in the refrigerator before packaging it.
• Freeze fruit in portions that can be thawed and used for a single meal or serving.
• Choose packing materials that are resistant to moisture and vapor; durable and leak-proof; resistant to cracking and brittleness at low temperatures; resistant to oil, grease and water; impermeable to absorption of off-flavors and odors; easy to seal and label. Some recommendations for fruit packed without added sugar or liquid include plastic freezer bags, vacuum packaging designed for freezing, rigid plastic containers and glass or plastic freezing jars. Recommendations for fruit packed with added sugar or liquid include rigid plastic containers and glass or plastic freezing jars.
• Do not use paper cartons, recycled plastic food tubs, thin plastic or any containers with cracks or poorly fitting lids.
• Label packaged fruit with the type of fruit, added ingredients, the date packaged, the number of servings and the date to use by. Frozen fruit should be used within 8 to 12 months of freezing for best quality.
• Freeze fruit as soon as it’s packaged and sealed. Otherwise, refrigerate it until you can. The sooner fruit is frozen efficiently, the better its quality will be preserved in the freezer.
• Don’t overload the freezer. Leave enough space for air circulation so that fruit freezes quickly.
• Thaw fruit in the refrigerator, under cold running water or in the microwave for immediate use.

Resources

Penn State Extension