To make preserves, you need fruit, sugar, acid and pectin, which thickens when activated by heat to set the resulting preserves. Pectin is found in most fruits, especially in their skins. Fruits high in pectin, including stone fruits, will thicken naturally when simmered. For low-pectin fruits like berries, the addition of store-bought powdered pectin is crucial. Because pectin levels among fruits vary, it’s important to rely on instructional guides from pectin packages if you’re substituting one fruit for another or using a blend of two or more.
No-cook jams, often referred to as freezer jams, skip the simmering and canning. Instead, chopped raw fruit are combined with sugar and pectin. The resulting condiment should be stored and frozen immediately.
Before chopping your plums, slice off a bite of each and taste to ensure it is just right. You want the boldest flavors for a no-cook preserve.
Plum-ginger freezer jam
• 3 pounds ripe but firm plums, pitted and cut into 1-inch pieces
• 1 cup super-fine sugar
• 2 tablespoons fresh ginger, scrubbed, grated
• 2 tablespoons lemon zest
• 2 tablespoons lemon juice, plus more to taste
• 1/4 teaspoon calcium powder, if needed
• 4 1/2 teaspoons powdered pectin
• 1/2 teaspoon kosher salt
Using a fork, crush the plums in a bowl to release some pulp and juices while keeping the fruit chunky. Toss with the sugar, then add the ginger and lemon zest and juice. Stir until the sugar dissolves. Measure the volume of your fruit mixture; you should have about 6 cups.
If your package of pectin comes with calcium powder, stir 1/4 teaspoon of the calcium powder into 1/4 cup water to dissolve. Set aside. Place the
4 1/2 teaspoons pectin in a stand blender. Bring 1 cup water to a boil, then pour it into the stand blender and blend. The mixture should become smooth. Stir the pectin mixture into the fruit until evenly combined, then stir in 4 teaspoons of the calcium water, if using. The jam should thicken. Add the salt, stir and taste. Adjust after tasting with more teaspoons of lemon juice, if necessary.
Transfer to clean airtight containers, cover and chill in the refrigerator for at least 24 hours and up to 2 weeks before serving.
Total time: 10 minutes, plus chilling; makes 6-7 cups.
There are a few different brands of powdered pectin, so the amount needed may change depending on which you buy.
If the package includes instructions for no-cook freezer jam, follow them and adjust the amount of pectin needed based on your volume of cut fruit.