Effect of ball milling on enzymatic sugar production from fractionated corn stover

Corn stover is a valuable feedstock for non-grain sugar production. Each anatomical part has different compo-sition and structural propertied. In this study, corn stover was divided into four parts (stem, leaf, husk, and ear). Their response to ball milling pretreatment and potential for sugar production by enzymatic hydrolysis were studied. Among four parts, the husk obtained the highest monosaccharide concentration due to its lower crys-tallinity and more suitable chemical composition. Ball milling pretreatment can enhance their structural prop-erties significantly and increase sugar yield. At 20% solid loadings, the monosaccharides concentration in all parts exceeded 80 g.L-1. However, due to the larger particle size, the husk had a poor response to ball milling pretreatment. In contrast, the best response was observed in stem due to the least particle size and lots of cavity structure. Therefore, the enzymatic hydrolysis efficiency of ball milled stem was the highest. Furthermore, the lignin content among various parts before ball milling was the critical factor for the difference in enzymatic hydrolysis efficiency, so as the ash content of the leaves, the crystallinity and water retention value of the stem. After ball milling, higher crystallinity, xylan content, D(10) and water retention value were the key factors leading to low enzymatic hydrolysis conversion of husk. This study provided a guidance for the better corn stover sugar production.