Thermochemical pretreatments of maize stem for sugar recovery: Comparative evaluation of microwave and conventional heating

•Microwave thermochemical pretreatments efficiently decomposed hemicellulose.•Microwave thermochemical pretreatments produced high yields of monosaccharides.•Microwave thermochemical pretreatments removed 96.1 % lignin content from biomass.•Efficient microwave thermochemical pretreatment was completed within 5 min.•Microwave heating consumed 25–34 folds less energy than conventional heating.