Hollow pickles may be caused by using too large a cucumber, faulty growth of cucumber, or a long lapse of time between picking and preserving. Shriveled pickles could be the result of placing cucumber in too strong a brine, too heavy a syrup, or too strong a vinegar, a long lapse between gathering and preserving, over-processing, or dry weather. White sediment in jar or crock can result when the salt used in pickling contains an anti-caking agent. Just because the jar of food has a seal, it cannot be assumed safe. A preserved food is safe when a USDA or similar recommended canning procedure has been correctly followed, when quality produce has been used, and when the canned food is stored and used correctly.
Sugar is added to improve flavor, help stabilize color, and retain the shape of the fruit.
In canned foods, sugar is not added as a preservative. There is mold on the top of the jelly. If mold is extensive, discard the product. Though mold growth can change the pH of products, the high sugar concentration would prevent any danger of botulism. Clemson University Cooperating with U.S. Department of Agriculture and South Carolina Counties.