4. Conclusions
Liquid hot water and dilute sulphuric acid pretreatments were found to be suitable technologies for the hydrolysis of hemicelluloses of olive stones at high temperatures. The conversion of hemicelluloses reached 93.4% and 100% at 230 C when using liquid hot water and dilute sulphuric acid, respectively. The maximum yields of D-xylose (21 kg/100 kg of olive stones) and D-glucose (11 kg/100 kg olive stones) were found in dilute sulphuric acid pretreatments performed at 200 C and 230 C, respectively, while hydrothermal processes provided the highest recovery of oligosaccharides
(17 kg/100 kg olive stones) at 210 C. Regarding organosolv pretreatment, the use of EtOH/H2O/H2SO4 mixtures at high temperature resulted in solids with high cellulose content (83.3%).