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 esteras e III) and CinnAE (cinnamic acid esterase)) for their ability to relea se ferulic acid from maize bran, a particularly rich source of ferulic acid. However, even though both enzymes exhibited significant activit es on novel feruloylated oligosaccharides derived from maize bran (inc luding FAXX (O-(5-O-feruloyl-alpha-L-arabinofuranosyl)-(1-->3) -O-beta -xylopyranosyl-(1-->4)-D-xylopyranose)), neither esterase was efficien t in removing ferulic acid from the whole bran, even in the presence o f other carbohydrases. It is shown that the kinetics of ferulic acid r elease from feruloylated oligosaccharides was influenced by (a) the na ture of the sugar-sugar linkage, and (b) the type of sugar present. Th e 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.