Metal contaminants, such as copper, iron and nickel, can often find be found in food we eat. These unwanted impurities from the soil or from machinery during harveting and processing, will degrade the food stuffs by catalyzing the oxidation of the fats in the food. A class of food additives known as sequestrants can be added to remove the problems caused by these impurities. The additives react with trace metals in foods, forming tightly bound complexes (sequestered), thereby preventing the decompostion of the food.

The sodium and calcium salts of EDTA (ethylenediaminetetraacetic acid) are common sequestrants in many kinds of foods and beverages.

EDTA (ethylenediaminetetraacetic acid). The EDTA molecule can bind to metal ions by forming six bonds to it - two from nitrogen atoms in amino groups and four from oxygen atoms in carboxyl groups.

To sequester means " to withdraw from use"

Formal Chemical Name (IUPAC)