title: Enzymatic modification of flaxseed fibers.
abstract: Flaxseed (Linum usitatissimum L.) fibers were modified by oxidoreductive and cellulolytic enzymes. The lignin amount and intrinsic plant peroxidase activity was evaluated by histochemical and spectrophotometric assays. Peroxidase activity was not found from bast fibers. The flaxseed fibers were further separated and treated with laccase to conjugate the model compounds, that is, the hydrophobic gallate molecules on fiber surfaces. Laccase was able to slowly oxidize fiber-conjugated phenolics, but no fundamental changes in fiber cell surface structure or notable coupling of the applied hydrophobic gallate molecules onto the fibers occurred, as revealed by Fourier transform infrared spectroscopy. The reactivity of the mature fibers was further investigated using cellulolytic enzymes. Cellobiohydrolase (CBH) and endoglucanase (EG)-rich enzyme preparations were applied to reach a hydrolysis degree of 1-6% (of the fiber dry matter) using a standard enzyme dosage. The CBH mixture altered the fiber surface morphology distinctly, and SEM images illustrated fibers in which the cellulose fibrils seemed to be loosened and partially hydrolyzed. In contrast, the effect of the EG-rich preparation without CBH activity was notable on the fiber surface, polishing the surfaces. The cellulolytic treatments were potentially interesting for specific enzymatic modifications of flax fiber surfaces, whereas the approach to use oxidoreductive enzyme treatments on mature linseed fibers offered little potential, obviously due to the low lignin content of the fibers.
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, P.O. Box 27 (Latokartanonkaari 11), FI-00014 University of Helsinki, Finland. pekka.maijala@helsinki.fi
authors.forename: Pekka
authors.initials: P
authors.lastname: Maijala
authors.forename: Marliina
authors.initials: M
authors.lastname: Mäkinen
authors.forename: Sari
authors.initials: S
authors.lastname: Galkin
authors.forename: Kurt
authors.initials: K
authors.lastname: Fagerstedt
authors.forename: Tiina
authors.initials: T
authors.lastname: Härkäsalmi
authors.forename: Liisa
authors.initials: L
authors.lastname: Viikari
mesh_terms: D002480:Cellulase / Q000378:metabolism*; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000378:metabolism*; D019597:Flax; D008855:Microscopy, Electron, Scanning; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase