Cookbook author Camilla Wynne calls her blueberry jam Bleu Matin (or Blue Morning). “Blue” refers to the macerated and slow cooked blueberries, and “morning” to the fact that coffee beans are steeped into those berries while they bubble away.
The coffee brings out the tart, fruity notes of the blueberries and tempers the sweetness of the jam. In her book “Jam Bake,” Wynne focuses on small-batch preserving and skips the water-bath canning approach (in which your filled jams are immersed in boiling water) for a riff on the old-fashioned open-kettle method, which relies on the heat of the jam itself to secure an airtight seal on your jars.
Wynne preheats her jars in the oven to sterilize them and ensure enough heat for proper sealing. (There is no need to sterilize the jar lids with this method because the jars are turned upside down during the canning process.) Whether this approach is as safe as the water-bath method endorsed by the USDA remains a concern for many.
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This jam can be finished in a water bath, if you prefer. Click here for step-by-step instructions to water bath canning.
This is a small-batch jam recipe. If you decide to make a larger batch, you will need a large pot and, likely, longer cooking time for the berries.
Equipment: You’ll need a 6-quart or larger heavy pot, such as an enamel-coated cast iron Dutch oven (not aluminum), a candy thermometer, as well as canning jars, lids and rings (we used eight 4-ounce jars). Also helpful: a canning funnel.
Storage: Without any processing, the jam can be refrigerated for up to 10 days or frozen for up to 3 months. Or it can be processed into the oven-sterilized jars or in a water-bath canner for 10 minutes, after which it should be shelf-stable for up to 18 months.
Make ahead: The blueberries can be macerated for up to 1 week before making the jam.
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