A jar of jelly does not go bad if kept unopened in a cool, dry, dark area. Once opened it should be refrigerated and is good for about 9 months. If you see mold or detect odor them throw it out.
Expiration dates on jar are estimates and are just best used by dates. Jams and jellies do not go bad until some time after being exposed to mold, fungus, and bacteria in the air. They have an almost indefinate shelf life if not opened.
If it smells or tastes bad, then do not eat.
What are fruit jellies?
Fruit jelly is a semisolid mixture of preserved fruit juice and sugar. In the United States, a fruit jelly is defined as a semisolid food that is made from at least 45% by weight of fruit juice extract and 55% of sugar content by weight. Some fruits are seasonal, and you might not access them easily during their off-season months. Food processing industries take this chance to preserve extracts from these fruits for use later in the year in a flavored and palatable form.
How are fruit jellies made?
You might wonder how a fruit jelly is made to have such a close resemblance to the taste, smell, and color of the original fruit despite it being a processed product. Contrary to the presumption of many, blending and preserving whole fruits does not yield a fruit jelly. Instead, the juice from the fruit is extracted, mixed with sugar, and subjected to heat. After some time, the mixture starts to thicken, forming the jelly. Some factors affect the thickening of this fruit extract. Some fruit extracts concentrate faster than others.
The main components of a fruit jelly are water, acids, pectin, and sugar. Sugar and water are just additives, while acids and pectin are contained naturally in fruits. Different fruits have different concentrations of acids and pectin, and sometimes the concentration of these ingredients may have to be enhanced for the jelly to form.
Role Played by Pectin
For a fruit juice extract to form a gel, pectin must be present. It determines the continuity of the gel structure in the final product. The average percentage of pectin in jelly is approximately 0.5 to 1.5 percentage by weight.
Pectin is found in a plant’s cell walls, and it is expected that some fruit extracts have enough pectin content to form a gel. However, when making a fruit jelly, you should always assume that the pectin content is not sufficient and acquire processed pectin from reliable manufacturers. The pectin from such manufacturers is usually pure.
When using such pectin, the standard ratio of pectin to sugar is approximately 18 parts of the pectin part. The rigidity of the gel formed is dependent on the sugar concentration and the acidity of the medium.
Role Played by Acids
Firmness in a fruit jelly is dependent on the acidity in the fruit extract. The optimum firmness is obtained at a specific pH. This pH level requirement may vary for different types of pectin used but the optimum gel form at a pH range of 3.1 to 3.3. pH levels outside this range either form too hard gels (weeping) or result in poorly structured gels. The acidity of the fruit extract also determines the temperature at which the gel sets.
Role Played by Sugar in A Fruit Jelly
Sugar contributes to the thickening of the gel during processing. It may also act as a flavor for some fruits which lack considerable amounts of sucrose. At a concentration of 55% by weight, sugar also serves as a preservative. Low sugar content in fruit jelly creates a medium suitable for the growth of molds and yeasts.
Since it keeps a very long time you can store in your bunker as a food store.