Enzymatic saccharification of sugar-beet pulp

Nine commercial enzymatic preparations have been tested for their ability to release ferulic acid, rhamnose, arabinose, and galacturonic acid from sugar-beet pulp. SP 584, SP 585, and SP 342 from Novo Nordisk gave the highest release of ferulic acid, arabinose, and rhamnose. SP 584 and SP 585 degraded the pulp more rapidly than SP 342. Only SP 342 released free ferulic acid mainly in the early stages of hydrolysis; the ferulic acid was later released under esterified form. Admixtures of SP 342 or SP 249 with SP 584 or SP 585 released no free ferulic acid. The optimal pH for degradation of sugar-beet pulp by SP 584 in acetate buffer was 4; however, more (or similar levels of) galacturonic acid, arabinose, rhamnose, and galactose were solubilized when the reaction was carried out in water with faster release of galactose, arabinose, and galacturonic acid. A larger-scale hydrolysis by SP 584, carried out in water with a longer incubation time (120 h) and a higher enzyme/sugar-beet pulp ratio (3%), resulted in release of similar to 70% of ferulic acid and 65% of diferulic acid, similar to 80% of galacturonic acid (92% as monomers) and similar to 70% of the pulp neutral sugars (similar to 70-85% as monomers).