Chemicals capable of combining with metal ions to render them ineffective. They are also called sequestrants. Examples of chelating agents used in the food industry are ethylenediaminetetraacetic acid (EDTA), usually as the mixed calcium and sodium salt, and sodium polyphosphate. They are used as food additives to complex metal ions, particularly calcium and magnesium that could give rise to defects. For example they are added to canned fish to prevent development of struvite crystals, and to canned crabmeat to inhibit blueing of the meat.