Digestibility of Zinc Contained in Oysters

Abstract

To obtain information on the luminal absorption of oyster (Crassostrea gigas) zinc, the zinc action during an in vitro protease digestion of oysters was examined. More than 90% of the zinc was solubilized at pH 1.3 or 3.0 irrespective of the pepsin digestion. The solubilized zinc was partially re-precipitated by neutralization and trypsin digestion did not solubilize the re-precipitated zinc. When the pepsin digestion was performed at pH 5.0, the ratio of soluble zinc in trypsin digest decreased. When the trypsin digest was fractionated by Sephadex G-25, zinc was eluted later than the peptide fragments. These results indicate that the pH of the stomach juice rather than peptides released by the digestion of oyster protein highly contributes to the solubilization of oyster zinc in small intestine.