The decrease of total solid recovery as temperature increased can be basically attributed to hemicelluloses solubilisation. Fig. 2A also shows the percentages of hemicelluloses that remained in the solids at the end of each pretreatment in relation to the initial weight of hemicelluloses in the raw material. The addition of sulphuric acid and, mainly, the increase of temperature led to the depletion of the hemicelluloses in resulting solids. For example,experiments performed without acid at 210 C, 220 C and 230 C removed 69.1%, 83.9% and 93.4% of the original hemicelluloses, respectively, while dilute sulphuric acid pretreatments carried out at the same temperatures rose the percentages to 90.8%, 97.0% and 100% respectively.