Plum jelly is a sweet spread typically eaten on toasted bread, bagels, or other baked goods. It can be made from plums in a variety of ripeness and color, although sweet, dark plums tend to be among the most popular for making jelly recipes. While plum jelly is readily available in grocery stores, in specialty shops, and sometimes at farmers' markets, many people enjoy making their own batches from scratch at home. The process of cooking with plums and converting them to jelly is relatively simple. Cooks who are experienced with jelly-mixing often report that the most important aspect is understanding the correct use of the needed thickener known as pectin.
The fruits selected for plum jelly are usually Damson or Pluot plums. Many home cooks recommend that these fruits be as fresh as possible. If frozen plums are to be used, they should be the kind without added sugar or syrup.
Another important consideration is that plum jelly only sets properly when it is made in small batches, usually about 6 cups (roughly 1,420 ml) at the most. Doubling the recommended measurements of any ingredients typically results in jelly that is not thick enough.
Making plum jelly requires a handful of kitchen tools, including a large cooking pot, a ladle, and a pot known as a canner, which is used to sanitize the jars for storing the finished jelly. Some cooks who do a good deal of canning prefer to buy all of these supplies as part of a canning kit at a kitchen supply store. Properly sanitizing the storage jars is an important step for yielding a good batch of jelly. Using non-sanitized jars requires a longer processing time for the plum jelly, which can often cause it to become too liquid in consistency.
Once the plums are washed and peeled, they are typically chopped into small pieces and steeped in water that has just reached its boiling point. The plums are then simmered over medium heat for another 10 to 15 minutes. Cooking with fruit in this method usually requires stirring in order to prevent any burned pieces. The juice from the cooked plums is then strained and collected for mixing with the pectin to start the thickening process.
Pectin is most often available as a powder that can be found in most grocery store baking sections. Some cooks report that pectin with added sugar yields a thicker and sweeter jelly, though others prefer low- or no-sugar pectin. One of the keys to a uniform jelly is to mix the plum juice right away with the recommended amount of pectin before pouring and sealing the mixture in the jars.