Modified citrus pectin. Citrus pectin is a polysaccharide obtained from orange or lemon rinds. Pectin is indigestible by humans, and so it can be broken down into smaller saccharide units to increase its absorbability, thus turning it into modified pectin. Modified citrus pectin is a source of dietary fiber 1. Modified citrus pectin is considered generally recognized as safe (GRAS) and is approved for use as a food additive by the U.S. Food and Drug Administration (FDA) 2.