RELEASE OF FERULIC ACID FROM MAIZE BRAN AND DERIVED OLIGOSACCHARIDES BY ASPERGILLUS-NIGER ESTERASES

We have examined two A. niger esterases (FAE-III (ferulic acid esterase III) and CinnAE (cinnamic acid esterase)) for their ability to release ferulic acid from maize bran, a particularly rich source of ferulic acid. However, even though both enzymes exhibited significant activites on novel feruloylated oligosaccharides derived from maize bran (including FAXX (O-(5-O-feruloyl-alpha-L-arabinofuranosyl)-(1-->3) -O-beta-xylopyranosyl-(1-->4)-D-xylopyranose)), neither esterase was efficient in removing ferulic acid from the whole bran, even in the presence of other carbohydrases. It is shown that the kinetics of ferulic acid release from feruloylated oligosaccharides was influenced by (a) the nature of the sugar-sugar linkage, and (b) the type of sugar present. The results suggest that enzymic release of ferulic acid from maize bran is limited by physical and steric factors, not by the chemical nature of the linkage.