Pretreatment of lignocellulosic biomass for enhanced biogas production

Soybean Straw, Corn Stover and Sunflower Stalk as Possible Substrates for Biogas Production in Croatia: A Review

“…Because of different orientations throughout the structure, cellulose molecules have different levels of crystallinitylow crystallinity (amorphous regions), and high crystallinity (crystalline regions). 29 The crystalline form prevails in the major part of the cellulose and is hardly hydrolyzed in comparison to amorphous form. It is therefore expected that high-crystallinity cellulose will be more resistant to enzymatic hydrolysis, but reduction of crystallinity will increase the degradability.…”

“…30 Hemicellulose is a term used to represent a family of polysaccharides, such as pentoses (xylose and arabinose), hexoses (glucose, galactose, mannose and/or rhamnose), and acids (glucuronic acid, methyl glucuronic acid, and galacturonic acid). 27,29,31 The dominant component of hemicelluloses from hardwood and agricultural plants is xylan, while in softwoods glucomanan dominates. Hemicelluloses have a lower molecular weight than cellulose and are more amorphous, random, and branched with little strength that makes it highly susceptible to biological, thermal, and chemical hydrolysis.…”

“…Hemicelluloses have a lower molecular weight than cellulose and are more amorphous, random, and branched with little strength that makes it highly susceptible to biological, thermal, and chemical hydrolysis. 29,32 Lignin is the most complex polymer in nature. 27 It is a large and complex aromatic and hydrophobic amorphous heteropolymer consisting of three different phenylpropane alcohols: p-coumaryl, coniferyl and sinapyl, and their quantity varies according to species, maturity, and the space localization in the cell.…”

“…Lignin is a major barrier in the lignocellulosic biomass bioconversion process. 29,32 Harvest residues could be a good source for AD, due to large availability of biomass. However, agricultural biomass like sunflower stalk, corn stover, and soybean straw contain complex structure of lignocellulose, and does not contain easily fermentable free sugars (Table 3).…”

“…27,58 Pretreatment methods can be divided into different categories: mechanical, physical, chemical, biological and various combinations of these. 27,29,32 Further in the text, the most common pretreatment methods used for corn, soybean and sunflower harvest residues (or the residues similar to them according to the chemical composition) are discussed in more detail. To our knowledge, the AD of soybean straw and sunflower stalk has not been studied in detail so far.…”