Many people are changing their cooking habits to reduce the amount of sugar in their diets. Unless you use special recipes and gelling agents, however, your jams and jellies may fail if you eliminate or reduce the amount of sugar. Jellies and jams that contain modified pectin, gelatin, or gums may be made with noncaloric sweeteners. Jams with less sugar than usual also may be made with concentrated fruit pulp, which contains less liquid and less sugar. Two types of modified pectin are available for home use. One gels with one-third less sugar. A few brands of this type are available in supermarkets and sold as "light" pectin. The other is a low-methoxyl pectin which requires a source of calcium for gelling. If these are unavailable in your supermarket, you may find them in specialty stores or by mail order. To prevent spoilage, jars of these products must be processed longer in a boiling-water canner. Recipes and processing times provided with each modified pectin product must be followed carefully. The proportions of acids and fruits should not be altered, as spoilage may result. Acceptable refrigerator fruit spreads also may be made with gelatin and sugar substitutes. Such products spoil at room temperature, must be refrigerated, and should be eaten within one month. http://www.ext.nodak.edu/extnews/askext/jamjelly/4345.htm