Studies on enzymic release of ferulic acid from sugar-beet pulp

Abstract

Eighteen commercial enzymic preparations have been tested for their ability to release ferulic acid from primary cell-walls of sugar-beet pulp. Three release patterns were found: (a) no or little, esterified ferulic acid; (b) only esterified ferulic acid; or (c) a mixture of free and esterified ferulic acid. No enzymic complex released only free ferulic acid. Release kinetics were studied on two complexes, ‘Hemicellulase REG II’ (Gist-Brocades), which released the highest amount of esterified ferulic acid, and ‘Pektolase LM’ (Grindsted), which released one of the highest amounts of free ferulic acid with the lowest proportion of esterified ferulic acid. ‘Pektolase LM’ digested sugar-beet pulp rapidly, first releasing esterified ferulic acid, which was later deesterified. ‘Hemicellulase REG II’ showed an initial lag phase followed by fast liberation (between 32 and 48 h of incubation) of esterified ferulic acid. Sugar-beet pulp hydrolysates from ‘Pektolase LM’ and ‘Hemicellulase REG II’ were fractionated on DEAE Sephacel. The results showed that esterified ferulic acid was present either linked to fragments of pectic polysaccharides poor in arabinose (∼40% of esterified ferulic acid injected) or to arabinose oligomers (∼60%). © 1994 Academic Press.