Additional file 1: Figure S1. Study for the optimum solids and enzyme loading conditions. Figure S2. The color gained by the solutions after: A blank experiments in a H2O and b DMSO:H2O (4:1) mixture and B in pure aqueous solution of sugars in the presence of (a) sodium tetraborate decahydrate and NaOH, (b) buffer citrate phosphate (5 mM) and NaOH and (c) sodium tetraborate decahydrate, buffer citrate-phosphate (5 mM) and NaOH. Table S1. Composition for each lignocellulosic biomass sample. Table S2. Sugars (glucose and fructose, 2.5 wt. %) conversion to HMF in the absence of any additional catalyst (150 °C, 60 min). Table S3. Effect of homogeneous and heterogeneous catalysts on the decomposition reactions of sugars (glucose and fructose 2.5 wt. %) to organic acids (150 °C, 60 min).