• When possible, preserve fresh, locally-grown plums for the best quality and nutritional value.
• Know when fresh plums are available in your state with this seasonal food guide.

• If this is your first time freezing or it has been awhile, it is recommended that you read General Freezing Information before beginning.  

1. Selection & Ingredients

• Select ripe, deep-colored, firm fruit. Do not use fruit that show signs of decay or mold.
• Use 2-2 ½ lbs of plums or prunes per quart container.
• Anti-darkening treatment (optional):  
  • Ascorbic acid (Vitamin C) –or-
  • Commercial ascorbic acid mixture (follow manufacturer’s directions for treating fruit)
• Sugar for sugar or syrup pack (optional)
  • NOTE: Unsweetened, dry packed fruits will lose quality faster than those packed in sugar or syrup.

2. Freezing Equipment

• Cooking pot (if using liquid pack method)
• Colander
• Cutting board
• Knife
• Ruler/headspace tool
• Use clean packing containers and materials that are moisture and vapor-proof/resistant:
  • Rigid containers (glass jars and hard plastic containers) are especially good for freezing foods with liquid. Covers for rigid containers should fit tightly.
    • Square or rectangular, straight-sided rigid plastic containers make the best use of freezer space.
    • Wide-mouth, dual-purpose glass jars made for canning and freezing are tempered to withstand extremes in temperature and allow for easier removal of partially-thawed foods.
    • Narrow-mouth dual-purpose glass jars can also be used but require greater headspace (to avoid expansion breakage at the shoulder) and foods must be completely thawed before removal.
  • Flexible bags or wrappings (plastic freezer bags, freezer paper and heavyweight aluminum foil) are best for freezing food products with little or no liquid.
    • Vacuum packaging removes more oxygen than other freezing methods (Refer to manufacturer's instructions.)

3. Prepare Equipment 

• Before use, wash reusable containers in hot soapy water and rinse well. Dry.

4. Prepare Fruit 

• Thoroughly wash plums or prunes.
• Leave whole or cut into halves or quarters and pit. 

5. Pack

Choose one of the following packing methods:

Unsweetened (Dry) Pack-

• To prevent darkening, dissolve 1/4 teaspoon (750 mg) ascorbic acid in ¼ cup cold water for each quart of fruit. Sprinkle over the fruit.
  • If using commercial ascorbic acid mixture, follow manufacturer’s directions.
• Pack fruit tightly into containers, leaving proper headspace for the container type (see Headspace table below).
  • Treated fruit slices can also be frozen first on a tray and then packed into containers as soon as they are frozen.
• Before sealing, make sure sealing edges are free of moisture or food.
  • If using flexible bags or wrap, remove as much air as possible.
• Seal.

Sugar (Liquid) Pack-

• To prevent darkening, dissolve 1/4 teaspoon (750 mg) ascorbic acid in ¼ cup cold water. Sprinkle over the fruit.
  • If using commercial ascorbic acid mixture, follow manufacturer’s directions.
• Mix 1/2 cup sugar with 1 quart sliced fruit.
• Pack fruit tightly into containers, leaving proper headspace for the container type (see Headspace table below).
  • If using rigid containers, place a small piece of crumpled water-resistant paper on top to hold fruit down.
  • If using flexible bags, remove as much air space as possible.
• Before sealing, make sure sealing edges are free of moisture or food.
• Seal.

Syrup (Liquid) Pack-

• A 30% sugar syrup is recommended for most fruits
  • Lighter syrups (10-20%) are lower in calories and desirable for mild-flavored fruits, such as melons.
  • Heavier syrups (40-50%) may be needed for very sour fruits.
  • Plan for 1/2 to 2/3 cup syrup for each pint of fruit.
• To make the syrup, dissolve sugar in lukewarm water, mixing until the solution is clear (see Sugar Syrup Recipe table below).
• • Cool syrup before using. (Syrup can also be prepared the day before and refrigerated until ready to use.)
• To prevent browning, add 1/2 teaspoon (1500 mg) ascorbic acid to each quart of cooled syrup.
  • If using commercial ascorbic acid mixture, follow manufacturer’s directions.
• Add 1/2 cup syrup/pint container or 1 cup syrup/quart container.
• Add sliced fruit, pressing down firmly, and cover with additional syrup, as needed, leaving the proper headspace for the container type (see Headspace table below).
  • If using rigid containers, place a small piece of crumpled water-resistant paper on top to hold fruit down.
  • If using flexible bags, remove as much air space as possible.
• Before sealing, make sure sealing edges are free of moisture or food.
• Seal.

6. Storage

• Label with the name of food, date, and type of pack.
• Freeze packaged fruits as quickly as possible to 0°F or below.
  • For quickest freezing, place containers in single layer in freezer.
• Most fruits will maintain high quality for 8-12 months at 0°F or below.