Environmental Engineering Reference
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Fig. 2 Schematic presentation of coordinate action of hemicellulases on hemicellulose backbone
into monomeric components
increasing the concentration of any inhibiting compounds in the hydrolysate, sum-
marized in Fig. 2. These compounds are produced from hemicellulose hydrolysates
by specialized microorganisms under a battery of cultivation techniques.
3 Technical Details - Materials and Methods
3.1 Hemicellulose Hydrolysis
In contrast to cellulose, which is crystalline, strong, and resistant to hydrolysis,
hemicellulose has a random, amorphous structure with little strength. It is eas-
ily hydrolyzed by dilute acid or enzymatically using an arsenal of hemicellulase
enzymes [19]. In addition, the lignocellulose can be mildly pretreated with chemi-
cals prior to enzymatic hydrolysis for better saccharification into fermentable sug-
ars. This reduces the crystallinity of the biomass and makes it more amenable to fur-
ther coordinated enzymatic reactions [18, 20]. Various pretreatment strategies with
dilute acid, alkali, ammonia fiber explosion, hydrogen peroxide, steam explosion,
wet oxidation, liquid hot water, sodium sulfite, etc., have been discussed [3, 21].
3.1.1 Dilute Acidic Hydrolysis
Dilute sulfuric acid hydrolysis is a favorable method for pretreatment before enzy-
matic hydrolysis and also for the conversion of lignocellulose to sugars [22].
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