Ascorbyl stearate (C<sub>24</sub>H<sub>42</sub>O<sub>7</sub>) is an ester formed from ascorbic acid and stearic acid. In addition to its use as a source of vitamin C, it is used as an antioxidant food additive in margarine (E number E305). The USDA limits its use to 0.02% individually or in conjunction with other antioxidants.