Efficient production of chito-oligosaccharides through microwave-assisted hydrothermal and low-acid-mediated degradation and deacetylation of chitin

The conventional method for producing chitin oligosaccharides involves high-temperature hydrolysis in highconcentration acid. In this study, we present an alternative method using microwave-assisted hydrothermal and diluted acid (0.12 mol/L) hydrolysis. After batched reactions, the liquefaction rate of chitin can reach almost 50%, and the sugar product yield is about 27%. Furthermore, this method leads to the reduction of the average particle size of chitin by approximately 70%, a decrease in the degree of acetylation by about 35%, partial destruction of the intermolecular hydrogen bond network, and the breaking of glycosidic bonds. These changes result in the exposure of more hydroxyl groups and enzyme binding sites, which may facilitate a subsequent enzymatic treatment. The method is a feasible alternative to obtain chitin oligosaccharides with a low environmental impact and operating cost.