Michigan State University Extension
Preserving Food Safely - 01600895
3-l/2 lb. ripe plums 3 lb. ripe Concord grapes 1 cup water l/2 tsp. butter or margarine to reduce foaming (optional) 8-l/2 cups sugar l box (l-3/4 oz.) powdered pectin
YIELD: About l0 half-pints
PROCEDURE: Wash and pit plums; do not peel. Thoroughly crush the plums and grapes, one layer at a time, in a saucepan with water. Bring to a boil, cover, and simmer l0 minutes. Strain juice through a jelly bag or double layer of cheesecloth. Measure sugar and set aside. Combine 6-l/2 cups of juice with butter and pectin in large saucepan. Bring to a hard boil over high heat, stirring constantly. Add the sugar and return to a full rolling boil. Boil hard for l minute, stirring constantly. Remove from heat, quickly skim off foam, and fill hot, sterile jars, (see directions below for sterilizing jars) leaving l/4-inch headspace. Adjust lids and process.
Sterilization of Empty Jars
To sterilize empty jars, place them right side up on the rack in a boiling-water canner. Fill the canner and jars with hot (not boiling) water to 1 inch above the tops of the jars. Boil 10 minutes at altitudes of less than 1,000 feet. At higher elevations, boil 1 additional minute for each additional 1,000 feet elevation. Remove and drain hot sterilized jars one at a time as filled.
RECOMMENDED PROCESS TIMES FOR GRAPE-PLUM JELLY IN A BOILING-WATER CANNER
Process Times at Altitudes of
Style of Jar 0- 1001- 6001- Pack Size 1000 ft. 6000 ft. 8000 ft.
Hot Half-pints 5 min. 10 min. 15 min. or pints