In vitro digestibility of zinc contained in oyster was studied. Oyster (Crassostrea gigas) was boiled in water for 5 min and then homogenized. The homogenate was incubated with Tris-HCl buffer (pH 7.4) or 0.1N HCL Rate of soluble zinc in Tris buffer or 0.1N HCl was 15 or 87%, respectively. When the homogenate was digested with pepsin in 0.1N HCl. the rate of soluble zinc was increased to 92%, but when the pepsin-digest was further digested with trypsin. the rate of soluble zinc was lowered to 56%. In a Sephadex G-25 gel chromatography of the pepsin digest. zinc was recovered in one low molecular weight (<10,000) fraction. This zinc fraction was further digested by trypsin because zinc was recovered in plural lowered molecular weight fractions in a fractionation of the pepsin-trypsin digest by Sephadex G-25.
