Homemade Jam Making: A Flavor Blast from the Past


While the steps between whole fruit and a quaint and colorful jar of delicious, spreadable blackberries may seem challenging and mysterious, the formula couldn’t be simpler: Fruit plus sugar equals jam. That’s the simplicity of a process that dates back at least as far as Roman times. (If you’re looking for a time-tested recipe, try Marcus Gavius Apicius’s offerings in Of Culinary Matters—assuming you read Latin.)

Making jam may tap into childhood nostalgia or conjure up bucolic visions of lush fields and farmhouses. It may be just the right gift for a special event or the ideal way to enjoy your favorite fruits at the peak of their season, in any season. Mastering the basic concepts of jam making and storage will free you to explore just about any flavor combination.

Mastering the Technique

If you’ve already considered the finer points of jam versus jelly versus preserves (or even marmalade), congratulations. If not, a quick overview: Jam is made by cooking crushed fruit or fruit pulp with sugar; jelly combines fruit juice and sugar; preserves mix crushed fruit and fruit juice with sugar. The difference is noticed mostly in texture. Jams and preserves spread easily and have a heartier texture that includes chunks of fruit. Jellies are a firmer, glossier spread with a smooth texture throughout.

The magic-maker in all of these processes is pectin, a naturally occurring substance found in the cell walls of plants. Pectin is nature’s gelatin, and most fruits have enough pectin to turn a boiling mass of sugar-coated strawberries into a thick, delicious spread.

A basic recipe for jam includes two cups of fruit, four cups of sugar, and one-quarter cup of lemon juice. (The lemon juice enhances the effect of pectin.) Mash the fruit into a chunky paste, then mix it with sugar and lemon juice. Place all ingredients in a saucepan and stir over low heat until the sugar has dissolved. Then, increase the heat until the mixture reaches a rolling boil. Continue to boil until the temperature of the jam-to-be reaches 220 degrees Fahrenheit (105 degrees Celsius). Remove the completed jam from the heat.

If your jam has trouble holding together, you may need to cook it a bit longer (to evaporate more liquid and concentrate pectin), add more sugar, add more lemon juice, or, if absolutely necessary, add commercially produced pectin. If your jam is too firm, reduce the cooking time or quantities of sugar and acid.

If you plan to eat your work right away, jam can be stored in an airtight container in the refrigerator. For long-term storage (or sharing), canning is by far the best option.

Preserving Your Work

Canning will keep your hard (and delicious) work fresh for months and also allow you to share your efforts with sure-to-be-grateful friends and family. To can jam, use glass jars with two-piece metal lids. Ball and Kerr are popular brands. Sterilize the jars by soaking them in hot water (180 degrees Fahrenheit) or just running all parts through a cycle in your dishwasher.

Fill a large stockpot with water and bring to a boil. Add your freshly cooked jam into the jars, leaving about one-quarter inch of space at the top of the jar. Place the top lid on the jar, then lightly tighten the band portion of the lid onto the jar. Carefully place the full jars in the pot of boiling water for about ten minutes. Water should cover the jars by at least an inch or two, and should also flow freely around the jars. A “popping” sound after the jars have been removed means the airtight seal has formed and your jam is safe! Sealed jars should be stored in a cool, dark place.