Michigan State University Extension
Preserving Food Safely - 01600631
Jam or jelly is too soft or syrupy if it is:
-Undercooked. (Undercooked jelly is syrupy and will not set).
-Made in too big a batch. (Jelly should always be made in a small batch, using no more than 4 to 6 cups of juice for one cooking. With a larger batch it is necessary to boil the mixture longer than usual to bring it to the jellying stage; however, long boil- ing often produces a strong caramelized flavor and darkened color. If a larger batch of jelly is boiled for the usual time, it will be undercooked). DO NOT DOUBLE A RECIPE FOR JELLY.
-Made with too much juice in the mixture.
-Made with too little pectin (fruit was overripe or too little added pectin was used).
-Made with too little acid.
-Made with too little sugar. (If jelly made with too little sugar is boiled for the usual length of time, it will be syrupy and runny. Jelly made with too little sugar requires longer boiling to reach jellying stage. But by the time it reaches this stage the jelly will be tough). DO NOT DECREASE THE AMOUNT OF SUGAR IN A JAM OR JELLY RECIPE.
-Made with a great excess of sugar. (Jelly made with excess sugar is so soupy that it does not hold its shape. If commercially canned or frozen fruit or juice is used to make jellied products, the excess sugar will probably cause the jelly to be syrupy. Only unsweetened commercial preparations can be used to make jelly or jam).