Calcium ascorbate. (bp) calcium ascorbate is a compound with the molecular formula cac12h14o12. It is the calcium salt of ascorbic acid, one of the mineral ascorbates. It is approximately 10% calcium by mass. As a food additive, it has the e number e 302. It is approved for use as a food additive in the eu, usa and australia and new zealand. Identifiers cas number 5743-27-1