KE LIANG B. CHANG*, JOHN LEE AND WEN-RONG FU

National Taiwan Ocean University, Department of Food Science, 2 Pei-Ning Road, Keelung 202, Taiwan, Republic of China.

ABSTRACT

   The hydrolysis of chitin (93% N-acetylation) by hydrochloric acid produced N-acetyl-chito-oligosaccharides (NACOs) with low degrees of polymerization (DP) from 2 to 6. The HPLC retention time of NACOs decreased with increased water content in the mobile phase. A gradient elution procedure, using acetonitrile to water (v/v) ratio lowered linearly from 80/20 to 60/40 within 60 min, provided optimal resolution and characterization for the NACOs. The natural logarithm of the retention time of NACOs correlated linearly with the DP values. Hydrolysis of chitin followed a series-parallel reaction mechanism. At the same time the NACOs with higher DP's were generated from chitin, and were degraded by hydrochloric acid to form products with lower DP's. More NACOs with higher DP's were produced under conditions with higher concentrations of hydrochloric acid and a shorter reaction period. Higher temperatures facilitated the generation of NACOs with lower DP's.

Key words: Chitin, N-acetyl-chito-oligosaccharides, acid hydrolysis, HPLC.