Background:
Biomass use for the production of bioethanol or for the production of platform chemicals requires the efficient biomass breakdown to fermentable monosaccharides. Lignocellulosic feedstocks often require a physicochemical pretreatment prior to enzymatic hydrolysis. Optimal pretreatments can be different for different feedstocks and should not lead to biomass destruction and the formation of toxic products. The influence of six mild sulfuric acid or water pretreatments at different temperatures on the enzymatic degradability of sugar beet pulp was examined.
Results:
An optimal pretreatment of 15 min at 140 degreesC in water can solubilize 60 w/w% of the total carbohydrates present, mainly pectins. Higher severities lead to the destruction of solubilized sugars and to the subsequent production of the sugar degradation products furfural, hydroxy methyl furfural, acetic acid and formic acid. The pretreated samples were enzymatically degraded successfully with an experimental cellulase preparation.
Conclusions:
Pretreatment of sugar beet pulp greatly facilitates the subsequent enzymatic degradation within economically feasible times ranges and enzyme dosages. In addition, pretreatment of sugar beet pulp can be useful to fractionate functional ingredients like arabinans and pectins from cellulose. The optimal combined severity factor to enhance the enzymatic degradation of sugar beet pulp is between Log R'(0) = -2.0 and Log R' (0) = -1.5. Optimal pretreatment and enzyme treatment solubilized up to 80% of all sugars present in optimally pretreated sugar beet pulp, including > 90% of the cellulose.