초록
This study examined the effects of sub- and supercritical water pretreatments on the physicochemical properties of crab shell α-chitin and its enzymatic degradation to obtain N,N'-diacetylchitobiose (GlcNAc)<SUB>2</SUB>. Following sub- and supercritical water pretreatments, the protein in the crab shell was removed and the residue of crab shell contained α-chitin and CaCO<SUB>3</SUB>. Prolonged pretreatment led to α-chitin decomposition. The reaction of pure α-chitin in sub- and supercritical water pretreatments was investigated separately; we observed lower mean molecular weight and weaker hydrogen bonds compared with untreated α-chitin. (GlcNAc)<SUB>2</SUB> yields from enzymatic degradation of subcritical (350<SUP>o</SUP>C, 7min) and supercritical water (400<SUP>o</SUP>C, 2.5min) pretreated crab shell were 8% and 6%, compared with 0% without any pretreatment. This study shows that sub- and supercritical water pretreatments of crab shell provide to an alternative method to the use of acid and base for decalcification and deproteinization of crab shell required for (GlcNAc)<SUB>2</SUB> production.