CHEMICAL COMPOSITION OF THE EDIBLE OYSTER SHELL CRASSOSTREA MADRASENSIS (PRESTON 1916)

Oysters coming under the Genus, Crassostrea and Saccostrea are observed along the Indian coasts. Among them four species are considered economically important including Crassostrea madrasensis[1], Crassostrea gryphoides (Schlothein 1813), Crassostrea rivularis (Gould, 1850) and Saccostrea cucullata (Born, 1890). Crassostrea madrasensis, the dominant among them has been selected for this study. The procedure of analysis of the samples was based on AOAC 2005 standards. Flame Photometry, ICP and CHNS analysis was used to find out the precise values for Ca and Na; Sr and Mg; and C and S respectively in the shell of Crassostrea madrasensis. Calcium as calcium oxide was observed as the largest constituent at 47.49% closely followed by total Carbon at 43.87%. The remaining elements Sodium as sodium oxide at 1.119%, Magnesium as magnesium oxide at 0.619%, Sulfur as sulfur dioxide at 0.403%, Strontium as strontium oxide at 0.020% and water as moisture exist only in negligible percentages. The utilization of oyster shell relates to the chemical constituents which contribute more than 90% of the shell. In Crassostrea madrasensis, these elements have been identified as Calcium and Carbon and have been quantified as contributing on an average 91.36% by weight of the shell in this study. These can effectively be used in the pharmaceutical, fertilizer, lime, cement and poultry feed industries.