Complete conversion of agarose into water soluble agaro-oligosaccharides by microwave assisted hydrothermal hydrolysis

•Microwave assisted hydrothermal hydrolysis is attempted for the degradation of agarose.•Complete liquefaction of agarose was achieved under optimized treatment condition.•The sugar yield (monosaccharide and oligosaccharides combine) is over 90%, most of sugars are valuable agaro-oligosaccharides.•Both even- and odd-numbered agaro-oligosaccharides were obtained from the microwave assisted hydrothermal hydrolysis.