Answer from a Master Food Preserver:

Many people want to reduce the sugar in their jams. There are safety concerns when altering the amount of sugar, the preparation method, or the type of pectin used from a recipe. Fruit usually has high "water activity" (naturally occurring water) and needs a certain amount of sugar to bind with the water to prevent the growth of mold and yeast in the jam.

Recipes for jam using standard pectin usually have large amounts of sugar. The sugar makes the jam safe when canned and helps with the gelling process. Canning your jam with only two cups of sugar could spoil more easily. With that lower amount of sugar, freezing the jam is the only safe way to store until ready to eat.

As an alternative, there are reduced- and no-sugar pectins available (called low-methoxyl) in powder and liquid formulations. Because they are low- or no-sugar, you should follow the recipe insert in the box of pectin for your choice of jam. Some recipes allow sugar substitutions with honey, corn syrup, or even artificial sweeteners.  

Have a Question? Submit yours here