When fruits are low in acid, add lemon juice or citric acid. Added acid is always required with some types of commercial pectins. Sometimes the acid is already combined with the commercial pectin. Check the ingredients list. Sugar Sugar must be present in the proper proportions with pectin and acid to make a good gel.
Sugar also prevents the growth of microorganisms in the product and contributes to the taste.
Never change the amount of sugar in a recipe. Sweeteners such as brown sugar, sorghum, and molasses are not recommended because their flavors overpower the fruit and their sweetnesses vary. You can replace part but not all of the sugar with light corn syrup or light, mild honey. For best results, use tested recipes that specify honey or corn syrup. Artificial sweeteners cannot be substituted for sugar in regular recipes because gel formation specifically requires sugar.