Assessing the availability of two bamboo species for fermentable sugars by alkaline hydrogen peroxide pretreatment.

This study comprehensively investigated two bamboo species (i.e. Neosinocalamus affinis and Phyllostachys edulis) in terms of their cell wall ultrastructure, chemical compositions, enzymatic saccharification, and lignin structure before and after alkaline hydrogen peroxide pretreatment (AHP). During AHP, Neosinocalamus affinis (NAB) had higher delignification than Phyllostachys edulis (PEB), and thus showed better enzymatic digestibility (93.05% vs 53.57% for glucan). The fundamental chemical behavior of the bamboo lignins was analyzed by fluorescence microscope (FM), confocal Raman microscope (CRM), molecular weight analysis, and 2D HSQC-NMR. Results indicated that the PEB has thicker cell wall and more concentrated lignin in its compound middle lamella and cell corner middle lamella than NAB. Moreover, PEB lignin contains more G units (S/G of 0.95), in evident contrast to that of NAB lignin (S/G of 1.30), which favor the formation of C-C linkages, thus impeding its degradation during the AHP.

Enhancement of eucalypt chips' enzymolysis efficiency by a combination method of alkali impregnation and refining pretreatment.

A combination process of alkali impregnation and refining was used as a pretreatment to improve the production of fermentable sugar. The surface structures and crystallinities of wood samples were characterized to explain the relationships between the pretreatment action and enzymatic efficiency. After refining, the reducing sugar contents in hydrolyzates were analyzed by UV-Vis and HPLC. The results showed that the enzymatic efficiency could be improved by the combined pretreatment, due to the increment of specific surface area and the release of more free hydroxyls. Comparing to the sodium hydroxide and deionized water, the impregnation with magnesium hydroxide had low refining energy consumption and high yield of reducing sugar (glucose and xylose) in enzymolysis process, where about 560 kWh/t of the energy was saved in refining, and the yield of the reducing sugar was as high as 91.53%. And the enzymolysis could be improved by a certain amount of magnesium ions.