2.2.2. Alkaline-acid method (AA method) (Cao et al., 1996) Five grams of steeped stalks were mixed with 100 ml of
2.9 M NH4OH in an Erlenmeyer flask and incubated in the orbital shaker for 2, 7, 15, 24 h at 26 C. The delignified
residue was separated from the lignin containing liquid through centrifugation, and residual ammonia was removed
washing twice with deionised water and by vacuum evaporation. The solid was then treated with 100 ml of 0.3 N HCl at
100 C in a reflux system for 1 h. The resulting acid hemicelluloses hydrolysate obtained was neutralized by NaOH and
analysed for sugars, while the cellulose residue was washed with water until neutral pH, dried at 50 C to constant
weight, and analysed for cellulose content.