Most freezer jam recipes use only a handful of ingredients.
Freezer jam has several advantages over heat-processed canned jam, including its vibrant color, fresh taste and relative ease of preparation. Pectin is the most common ingredient used to make freezer jam set. Freezer jams containing less sugar will require alternative ingredients to set properly, however.
Natural Pectin
Pectin is a naturally occurring substance in fruit. Because different fruits at different stages of ripeness contain different levels of pectin, only some types of fruit can be successfully gelled without adding additional pectin from commercial sources. High-pectin fruits include sour apples and crab apples, many plums, cranberries, tart blackberries and boysenberries, wild Concord grapes and lemons. These fruits can often be mixed with low-pectin fruits to make freezer jam.
Commercial Pectin
To take the guesswork out of gelling freezer jam, use a brand of commercial pectin that is labeled for use in no-cook jam. Commercial pectin is derived from apples or citrus fruit, and generally comes as a powder. When added to a jam recipe, it interacts with sugar to form a predictable gel as long as the correct ratios of fruit, pectin and sugar are present. Because some brands of pectin require a period of boiling for activation, it's important to choose one that's compatible with your recipe.
Gelatin
Pectin requires a fairly large amount of sugar to work properly, making it unsuitable for diabetics or others who wish to avoid consuming refined sugar. Gelatin, an animal product made from the carcasses of swine slaughtered for pork, has similar gelling properties to pectin regardless of the level of sugar present in the recipe. This makes it ideal for use in no-sugar-added freezer jam recipes. Gelatin is generally softened in cold water, then added to the fruit mixture and boiled briefly.
Agar-Agar
Agar-agar powder is a lesser known ingredient that is gaining popularity with professional chefs for its powerful gelling properties. Made of algae, it has eight times more gelling action than gelatin. To use agar-agar, simply boil it in liquid for one minute and let it cool. Don't add acidic liquids such as lemon juice; high acid levels can interfere with agar-agar's gelling. Like gelatin, agar-agar does not require sugar to work properly. It also cooks more quickly than pectin, keeping the fresh fruit taste of the jam intact.
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