Extension's tips for successful jams, jellies

August 8, 2006 (Updated December, 2007)
Carol Ann Burtness
Regional Extension Educator, Food Science
888-241-0720
Email: burtn002@umn.edu

One way to preserve summer fruits is by making jam or jelly. Carol Ann Burtness, food science educator with the University of Minnesota Extension, sat down recently to answer some of the most commonly-asked food preservation questions she receives this time of year.

Can I freeze fruit and make jam or jelly later?

Carol Ann: Yes. You can make jam or jelly later by freezing fruit in large pieces or whole. Measure the amount of fruit carefully before freezing. When you're ready to use it in a recipe, thaw fruit in the refrigerator until only a few ice crystals remain.

• If you use powdered pectin when making jam, do not add sugar before freezing. Freeze the measured fruit and record the amount on the container label. When you're ready to make jam, thaw the fruit and proceed with the recipe, adding the recommended amount of sugar and powdered pectin.


• If you use liquid pectin, combine the measured amount of sugar and fruit together before freezing, and record amounts on the container label. When you're ready to cook the jam, thaw the fruit-sugar mixture and proceed with the cooking and processing steps.


• Save freezer space by making juice for jelly before freezing. Boil the fruit to extract the juice. Pour cooled, strained juice into a freezer container, label and freeze. When you're ready to make jelly, thaw the juice, measure it and immediately add sugar and pectin. Follow the remaining cooking and processing steps.

What containers can I use for storing freezer jam?

Carol Ann: Use freezer containers with tight-fitting lids to prevent loss of quality. Good examples include canning jars or plastic containers with tight-fitting lids. Most plastic margarine or whipped topping containers have loose-fitting lids and are not designed for long-term freezer storage. Leave enough space at the top of the container for expansion during freezing. Wash lids and containers with hot, soapy water and rinse with hot water to prepare them for freezer jam.

The pectin package directions tell me to invert the jars for sealing. Is this a safe method?

Carol Ann: The USDA and the University of Minnesota Extension recommend a six-minute boiling water canning process for all cooked jam and jelly products. Some sealing methods call for turning the closed jars of hot jam or jelly upside down for 30 seconds to one hour. The vacuum seals of jars filled using this method tend to be weaker than those produced by a short, boiling water canning process. A weak seal is likely to fail during storage and allow for mold growth.

(Carol Ann Burtness is a food science educator with University of Minnesota Extension)