3.1. Raw material composition
The chemical composition of the raw material used in this study is shown in Table 1. Olive stones were a potential source of sugars, due to their contents of cellulose (26.1%) and hemicellulosic sugars (25.5%). The maximum potential yield of ethanol attainable from the cellulose fraction was 14.8 kg per 100 kg of dry olive stones. Dxylose (23.4%) was the main pentose in the hemicelluloses. Cellulose and hemicelluloses (52.5%), acid insoluble lignin (31.3%) and ash (0.7%) contents obtained in this study were similar to those found in literature [18].