Studies on chitin, 2. Effect of deacetylation on solubility

Abstract

AbstractA reproducible method for obtaining water‐soluble chitin and a relationship between solubility and degree of deacetylation of chitin were studied. It was found that the regenerated chitin isolated at low temperature from an alkali chitin solution left at 25°C for 48 to 77h showed very good solubility in water at 0°C. The degree of deacetylation of an alkaline treated chitin was determined by titration with hydrochloric acid. It increased rapidly to about 75% as the alkaline treatment time increased and began to level off to about 90% and only the regenerated chitin samples with around 50% of deacetylation were found to be soluble in water. The X‐ray diffraction diagrams showed that these were amorphous, although both chitin with lower degree of deacetylation and chitosan had crystallinity. The improved solubility of chitin with about 50% of deacetylation would be attributed to the partial deacetylation which probably brought about the destruction of secondary structure and also the increase of the hydrophilic property on account of the increased number of amino groups.