Making grape jelly is easier than you can think. This recipe is for the old-fashioned grape jelly which needs only two ingredients. We think that wild grapes or underripe Concord grapes make the best jelly but any regular red grapes will do.
Do avoid seedless white/green grapes which have little flavor and make a bland jelly. Seedless or with seeds doesn’t really matter, as the strainer will remove seeds.
Grapes for juice – use 14 oz of grapes for 1 cup of grape juice
3/4 cup sugar for every cup of grape juice
Optional: 2 tablespoons lemon juice
Wash and stem the grapes. Put into a kettle or large stainless-steel pot, mash down and cook slowly for about 10 minutes, until the juice flows freely. Water – ¼ or ½ cup for every 4 cups of grapes – may be added a little at a time to prevent scorching or sticking.
Bring to a boil over medium-high heat, stirring frequently. Reduce heat, cover pot loosely and boil gently. Stir and continue crushing grapes until softened, about 5 to 10 minutes.
Strain grapes through a dampened jelly bag or fine-meshed strainer or dampened cheesecloth in a sieve collecting the juice in a bowl. Leave the strained juice overnight in the refrigerator to allow the white crystals that sometimes form to settle. In the morning, pour off the juice carefully, discarding the sediment, if any, at the bottom.
Measure out 4 cups (leave the rest for another batch) and heat to a boil in a stainless-steel saucepan. For 4 cups of juice, you’ll need to add 3 cups of sugar and bring the mixture back to a full rolling boil. Boil quickly, stirring, until the candy thermometer reads 8 degrees above the boiling point of water (about 220°F) or until the jelly sheets off a spoon.
Note: The jelly needs to be cooked until it’s fairly thick so make sure you cook it long enough or you can add two tablespoons of lemon juice to the grape juice while it’s coming up to a boil and before adding the sugar.
Remove from heat and skim off any foam that forms. To prevent foam from forming add ½ teaspoon butter or margarine after you add the sugar. Ladle the hot grape jelly into hot, sterilized jars leaving ¼-inch of headspace.
Wipe the rims of the jars and add lids that have been washed and dried. Add screw bands and tighten until fingertip-tight.
Place jars on rack in boiling water bath canner and make sure they are completely covered with water (1-2 inches above the jars). Cover with lid and bring to a boil. Process ½ pints and 8 0z jelly jars for 10 minutes. Remove canner lid waiting 5 minutes, then remove the jars to a towel on the counter, and cool for 12 to 24 hours. Test sealing of jars by pressing lightly in center of lid and store jars that have sealed. Any jars that don’t seal may be refrigerated and used.