My grandma makes the best raspberry jam. I’m not biased. It’s an objective fact. Every September, she bustles about her kitchen filling mason jars with ruby red deliciousness, which she then ships across the country to her beloved grandchildren. But even with years of practice, Grandma has off days, when her jam doesn’t set.
Turns out there are quite a few possibilities why Grandma’s jams don’t jiggle, as explained in Sarah Owens’ Toast and Jam. While the self-taught baker wowed the culinary world with her James Beard Award–winning Sourdough in 2016, her latest book features both rustic baked breads and their toppings, sweet and savory.
"I prefer a softer, almost silky set and often leave the the pectin out altogether to make a syrup,” she writes. But if you want your jams, jellies, and preserves to gel, consider these four culprits before repurposing:
Pectin is a water-soluble fiber concentrated in the skins and cores of fruit that gives jams their gel. While all fruits make equally delicious jams, they don’t all have equal amounts of naturally-occurring pectin. Some, like blueberries, peaches, or strawberries, naturally contain less pectin, while others, like apples and citrus fruits, are naturally pectin-rich. But as fruit ripens, enzymes begin to break pectin down, making fruit softer and more difficult to gel. If preserving low-pectin or very ripe fruit, try adding an additional teaspoon or tablespoon of pectin, available at most grocery stores in the baking aisle.
You may hesitate to add sugar to already sweet fruit, but pectin needs the sweet stuff to set properly. If you use a no or low-sugar pectin and your jam is still liquidy, add 1/4 to 1/2 cup more sugar.
In order for pectin to bond with sugar and fiber at 220° F, pectin also needs acid. For a firmer consistency, try adding 1 to 2 more tablespoons of white vinegar or lemon juice.
Too much heat will start to break down pectin’s structure (and keep your jam from setting), while not enough heat won't let the water evaporate (and keep your jam from setting). After stirring pectin into the hot mixture, you should cook it for only 1 to 3 minutes before reaching a setting point at 220°F.
When making jams with high sugar content, you can use homemade pectin. To make your own pectin stock, quarter under-ripe green or crab apples. Place into a stock pot filled with water, then bring to a gentle boil over medium-high heat, cover, and cook for 30 minutes. Once the apples are soft, strain the mixture through a mesh sieve into a large bowl. You can use the "pectinified" liquid to replace water in high-sugar jam recipes.
Do you have any tips or tricks to ensure your preserves set? Any favorite no-fail recipes? Let us know in the comments!