2.2.1.3. Calcium carbonate removal. To the shell powder 7% HCl was added until no gas escapes under stirring. As a check, HCl of 10 ml were added to the mixture. Later it was filtered off and washed well with distilled water. The product was dried at 60◦C overnight as a result 50 g of chitin was obtained, this step was also known as demineralization