Studies On The Bioaccessibility And Rapid Removal Of Cadmium In Shellfish

Since the shellfish is vulnerable to be polluted by cadmium,the researches of the risk of cadmium exposure to human body,as well as the removal of cadmium,are both significantly important.This paper took advantage of a static in vitro gastrointestinal model to investigate the bioaccessibility of cadmium in cooked shellfish,the method for rapid removal of cadmium in living shellfish and the mechanism of it were also discussed.This paper involves three parts:In section one,the bioaccessibility of cadmium in shellfish after being cooked in four different methods,including boiling,microwaving,stir-frying and deep-frying,were estimated through imitating the demic digestion system.It turned out that the bioaccessibility of cadmium in cooked shellfish ranged from 37.8%to 73.3%and from 25.1%to 56.3%in the simulated gastric solution and in the simulated intestinal solution,respectively.According to the gastrointestinal digestion results,bioavailability of cadmium in cooked shellfish presented by the following trends:deep-frying,stir-frying,stir-frying,boiling.The concentration of cadmium in the deep-frying shellfish was 0.09 ?g/g after gastrointestinal digestion,which was 2.3 times as much as boiling shellfish.Therefore,boiling cooked shellfish had reduced the absorbing capacity of cadmium in the human body.In section two,the study analyzed the influence of Vc,EDTANa2,CaC12 and chitosan on removing cadmium of the living shellfish under the circumstances of artificial seawater.The orthogonal experiments were taken to develop the agent of rapid removal of cadmium in living shellfish.We found that the removal rate could reach up to 48%,as much 2.7 times as to blank after 9 h when the concentrations of Vc,EDTANa2,CaCl2 and chitosan were 1.5 g/L,1.5 g/L,1.5 g/L and 0.5 g/L,respectively.In section three,the mechanism of removal cadmium in shellfish was studied through the differential centrifugation.Accumulated cadmium in the shellfish muscle was typically separated into five subcellular pools:metal-rich granules(MRG),cellular debris,organelles,heat-sensitive protein(HSP)and metallothionein-like protein(MTLP).The concentrations of cadmium in five subcellular fractions after the removal were compared with the original concentrations.We have discovered that cadmium of subcellular fractions(MRG)organelles,cell debris and HSP)have decreased by 36.3%,57.2%,30.4%and 50.5%,respectively after 9 h,which indicated that the cadmium in organelles was the easiest to remove.However,cadmium in MTLP was increased from 153.5 ng/g to 402.4 ng/g through the intervention of the agents of removal,which showed that intracellular cadmium were difficult to excrete because it could easily combine with MTLP.