Effect of ultrasonic treatment on the molecular weight of carboxymethylated chitin–glucan complex from Aspergillus niger

Different factors affecting the efficiency of the ultrasonic depolymerization of the high-molecular-weight carboxymethylated chitin–glucan prepared from the fungal mycelium of Aspergillus niger have been investigated. The influence of the following parameters was examined: concentration of the chitin–glucan complex, duration of ultrasonic irradiation, reaction temperature and volume of the ultrasonicated solution. The optimized conditions for the efficient ultrasonic depolymerization include: polysaccharide concentration – 0.2 mg ml−1; volume of the sonicated solution – 25 ml; duration of the sonication – 10 min; and constant cooling of the sonicated sample in an ice–water bath.