Considering Regarding now, the effect of pretreatments on GS composition, after the applied chemical steps, the cellulose content continuously increased as expected. Alkali treatment was efficient removing hemicellulose. This was explained by the cleavage of the ester-linked substances, such as hemicelluloses, favoured under basic conditions. The lignin content remained practically constant. The alkali treated garlic straw (ATGS) contained 63% wt cellulose, 13% wt hemicelluloses, 4.6% wt lignin, and 9.6% wt ash (Table 1).