Journal of Advances in Food Science & Technology

Calcium fortified foods and supplements are the preferred options to meet the calcium needs of individuals unable to derive adequate dietary calcium. Although eggshells are a natural source of calcium carbonate, they are mostly disposed off as a waste product. Food, bakery and farm industries produce large amount of eggshells and their disposal poses a great environmental challenge. The aim of this study was to analyze the in vitro bio accessibility of calcium from the egg shell samples and the calcium salts prepared using eggshell powder using an in vitro dialysis procedure simulating intraluminal digestive phase.  Functional properties, total calcium, phosphorus content of eggshells as influenced by heat treatment and with/without membrane were also studied. The results revealed that raw eggshells without membrane had the highest swelling power of 1.92% at 95ºC, and boiled eggshells without membrane exhibited highest bulk density of 1.46 g/ml. Water absorption capacity was higher in raw eggshells (with membrane) while boiled eggshells (with/without membrane) had relatively higher oil absorption capacity. Eggshells without membrane had higher calcium content while eggshells with membrane had greater dialyzable calcium compared to skimmed milk powder and commercial calcium  supplement which served as standard. Calcium carbonate prepared from eggshell powder with membrane had highest dialyzable calcium (152 mg/g) followed by eggshell without membrane (91.49mg/g). The present study revealed that the calcium content of eggshell exhibits high bio-accessibility and prospects exist for its utilization as a natural raw material in the preparation of calcium salts.