Firm unbleached muslin or cotton flannel with the napped side turned in or four thicknesses of closely woven cheesecloth may be used. Jelly bags or cloths should be damp when extracting juice. A jelly, candy, or deep-fat thermometer should be used to determine doneness in jellied fruit products without added pectin. A boiling water bath canner is necessary for processing all unrefrigerated or unfrozen fruit spreads. To enjoy jams, jellies, and other fruit products at their best, make only a quantity that you can use within a year.
Jellies lose flavor, and color during storage.
For best results, make only one recipe at a time, using no more than 6 to 8 cups juice. Double batches do not always gel properly. Preparing the Containers Prepare the canning jars before you start to make the fruit product. Half-pint jars work best, unless a recipe specifies another size. Using larger jars can result in a weak gel.