Alkaline pretreatments involve delignification using dilute sodiumhydroxide, potassium hydroxide, ammonia or lime, usually under conditions milder than those of other pretreatment processes [7].This type of pretreatment consists of applying a basic solution to solubilize lignin–carbohydrate complexes by the breakdown ofalkaline labile aryl–ether bonds (e.g., O 4 and O 4) and by acid-base reactions involving both aliphatic (mostly due to carbo-hydrates) and aromatic hydroxyl groups (exclusively due to thepolyphenolic structure of lignin).