Enzymic release of ferulic acid from sugar beet pulp using a specific esterase from Aspergillus niger

We have purified and characterised a novel esterase (CinnAE) from Aspergillus niger. The enzyme demonstrated activity towards various soluble feruloylated oligosaccharides derived from sugar beet pulp (SEP) but, when acting alone, the esterase released only 0.9% of the alkali-extractable ferulic acid from SEP. However, when incubated with a mixture of endo-arabinanase and alpha-L-arabinofuranosidase, there was a 14-fold increase in ferulic acid release, demonstrating a strong synergy between these three enzymes. No increase in ferulic acid release was observed when SEP was incubated with CinnAE plus endo-(1,4)-beta-D-galactanase and beta-D-galactosidase, Hence, feruloylated arabinans in SEP are readily available for hydrolysis by arabinan-degrading enzymes, whereas feruloylated galactans are not available for hydrolysis by galactan-degrading enzymes.