Combine the blueberries (or strawberries) and the sugar in a medium saucepan. Mash berries slightly with a potato masher or the bottom of a fork. Bring mixture to a boil over medium-high heat, stirring occasionally.
As soon as the berries begin to boil, begin to stir.
Continue to cook and stir occasionally until jam begins to thicken. During the last few minutes of cook time, stir vigorously so that the mixture doesn't stick to the bottom of the pan.When the mixture reaches a gel consistency, remove pan from the heat.
Pour into a clean glass jar.
Video
Notes
Expert Tips
Stick to Berries Rich in Pectin: While you can use a variety of fruits, berries like blueberries and strawberries that are naturally rich in pectin yield the best results.
Cook Slowly for Thickness: The combination of fruit and sugar needs a solid 20 to 30 minutes of cooking time to thicken properly. Slow cooking helps evaporate the moisture, aiding in the thickening process.
Monitor Thickness According to Fruit: Different fruits have varying water content, affecting the time needed to reach the desired thickness. Start assessing your jam’s consistency around the 20-minute mark.
Uniform Fruit Size Matters: To ensure even cooking, make sure your fruit pieces are of similar size. Chop the fruit into halves or quarters before cooking.
Soft Texture, Big Flavor: Although jam made without pectin tends to be softer than its store-bought counterpart, its fresh and vibrant flavor more than compensates.