Uptake kinetics and absorption of calcium in apple matrices

The purpose of this paper was to study the kinetics of calcium uptake of blanched and not blanched apple tissue during impregnation treatments under vacuum or/and at atmospheric pressure. The relative absorption of calcium in rats, regarding calcium carbonate as reference substance, was also analyzed as a first approach. Apple impregnation is conducted (with and without previous blanching in saturated vapor) in isotonic glucose aqueous solutions containing calcium gluconate and lactate. A 50mm Hg vacuum pressure is applied for a time t(1) (0-180 min) or atmospheric pressure is used for a process time t(2) (0-7.5 h). Calcium uptake by apple tissue is influenced by system pressure, blanching, and impregnation time, reaching 500-4600 mu g Ca/g according to process variables. Preliminary data of true calcium absorption ranges between 74 and 86% regarding calcium carbonate.