Call me a snob, but I will not use pectin in my preserves. And, yes, I can tell if you have.
My annotated recipe for strawberry preserves in Nora Carey's Perfect Preserves: Provisions From the Kitchen Garden says that I've been making this recipe since 1990. My husband loves this so much that he has been seen eating it straight from the jar. It's pectin-free, it's beautiful to look at and it tastes fabulous, almost as good as fresh-picked berries. (You are using locally grown strawberries, aren't you?)
Robin Mather Jenkins writes for the Chicago Tribune, which provided the recipe analysis.
Makes 12 half-pint jars or 6 pint jars
5 cups sugar (divided use)
5 pounds strawberries, hulled (about 3 1/3 quarts, depending on the berries' size)
1/4 cup fresh lemon juice
Sprinkle 1 cup of the sugar over half of the strawberries in a large, shallow bowl. Add remaining strawberries; sprinkle with another cup of sugar. Cover; let strawberries stand overnight.
Transfer the berry mixture to a colander set over a Dutch oven; let the juices drain into the pan, reserving the berries. Stir the remaining 3 cups of the sugar into the pan; cook the juice mixture over low heat, stirring, until sugar dissolves, about 5 minutes.
Raise heat to high. Heat to a hard boil; add reserved strawberries and lemon juice. Boil mixture 5 minutes. Transfer the berries with a slotted spoon to the colander set over a bowl.
Boil the syrup 10 minutes, or until it is reduced slightly. Measure any strawberry juices that have accumulated in the bowl; add them to the boiling syrup. Continue boiling to reduce the mixture by the amount added.
Add the berries to syrup again; boil 5 minutes or until mixture reaches jellying point on a candy thermometer at 220 degrees. (To test without thermometer, place a tablespoon of the juices on a cold plate and chill. If the mixture is firm enough to remain divided when a finger is pushed through the center, it has reached jellying point.)
Spoon jam into sterilized jars; place in a boiling water bath. Process 10 minutes in boiling water bath.
Adapted from "Perfect Preserves: Provisions From the Kitchen Garden" by Nora Carey
Per tablespoon: 24 calories, 0 grams fat, 0 grams saturated fat, 0 milligrams cholesterol, 6 grams carbohydrate, 0 grams protein, 0 milligrams sodium, 0 grams fiber