Liquid hot water and alkaline pretreatment of soybean straw for improving cellulose digestibility

Soybean straw was pretreated with either liquid hot water (LHW) (170-210 °C for 3-10 min) or alkaline soaking (4-40 g NaOH/100 g dry straw) at room temperature to evaluate the effects on cellulose digestibility. Nearly 100% cellulose was recovered in pretreated solids for both pretreatment methods. For LHW pretreatment, xylan dissolution from the raw material increased with pretreatment temperature and time. Cellulose digestibility was correlated with xylan dissolution. A maximal glucose yield of 70.76%, corresponding to 80% xylan removal, was obtained with soybean straw pretreated at 210 °C for 10 min. NaOH soaking at ambient conditions removed xylan up to 46.37% and the subsequent glucose yield of pretreated solids reached up to 64.55%. Our results indicated LHW pretreatment was more effective than NaOH soaking for improving cellulose digestibility of soybean straw.