Strawberry jam is the ultimate way to preserve the berries so that they can be enjoyed long after the short season has passed. While making it is actually quite straightforward, it is important to avoid some common mistakes in order to achieve success.
Reducing the sugar: Conventional jam recipes require a lot of sugar, and that sugar is not just there to serve as a sweetener. The sugar binds to the water in the fruit, which otherwise would prevent the jam from thickening. The sugar essentially prevents this water from getting in the way, so what you are left with is a nicely set jam rather than a thin and runny one.
Not adding lemon: Lemon is important for a couple of reasons in strawberry jam. First, it is acidic, and acid helps balance the sugar in the jam so that it is not too sweet. Second, it is naturally high in pectin. If you are not using boxed pectin, lemons give the strawberries a boost since they are low in pectin, and pectin is crucial if you want your jam to thicken and gel.
Not cooking long enough: While it is important not to overcook your jam, which leads to the loss of that fresh strawberry flavor, you also don’t want to undercook it. Often, strawberry jam recipes only have you cook the fruit for a few minutes. While this does lead to an extra fresh-tasting preserve, it can also cause the fruit pulp to separate from the jelly as the jam cools. To prevent this separation, cook the fruit a few minutes longer, and use a potato masher to crush the berries as they cook. This will help release any trapped air from the fruit flesh, and will result in jam that stays integrated.
Follow this tip: Cook the jam a few minutes longer than the recipe calls for and mash the strawberries a little with a potato masher while they cook so that the fruit stays evenly distributed throughout the jam once it cools.