Agriculture Reference
In-Depth Information
Although there have been many promising achievements in fabrication of bio-
nanocomposites from cellulose and pectin fibers isolated from sugar beet shreds, there are
several issues to be addressed to in order to accomplish economically efficient production of
nanocomposites at larger scale. The most important one is high energy consumption during
the step of mechanical disruption of fibers to nanofiber which is usually conducted in high-
pressure homogenizator.
One of the ways to solve this problem could be combination of mechanical disintegration
with enzyme treatments which can be conducted at mild and controlled conditions. Although
use of enzymes has not yet been studied for such purposes on sugar beet shreds, results of
several studies indicate this approach as promising one for successful production of cellulose
nanofibers. In one of them, cellulosic wood fiber pulp was treated by endoglucanases or acid
hydrolysis in combination with mechanical shearing in order to disintegrate cellulose
nanofibers from the wood fiber cell wall. Enzyme treatment was found to be more efficient in
facilitating disintegration than acidic one, enabling production of cellulose fibers with
favorable characteristics for nanocomposite fabrication [72].
In another study, mild enzymatic hydrolysis has been introduced and combined with
mechanical shearing and a high-pressure homogenization, leading to a controlled fibrillation
down to nanoscale from softwood pulp. The milder hydrolysis as provided by enzymes in
comparison to more aggressive acid hydrolysis allowed longer and highly entangled
nanoscale fibrils, whose feasibility in reinforcing multicomponent mixtures was here
manifested by the observed strength of the gel networks down to low concentrations.
Resulting material of nanoscale cellulose fibrils showed superior characteristics for
application for reinforcement of nanocomposites and as templates for surface modification
[73]. In addition, nanoscale cellulose fibrils produced after enzymatic treatment open several
challenging options for materials science not only to tune the aqueous properties but also for
totally new applications, such as templates for functional nanostructures as novel high-value
product.
C
ONCLUSION
Thanks to their chemical composition reflecting in high content of polymer carbohydrates
and low lignin content, sugar beet shreds represent an excellent substrate wether they are
subjected to enzymatic or microbial conversion. Bioconversions of sugar beet shreds by
bacteria, yeasts anf fungi allow their utilization as value-added feed and soil fertilizers with
environmentally safe fungicide characteristics, as well as production of valuable products
such as food/feed grade enzymes and biogas. Converted by enzymes to monosaccharides,
sugar beet shreds are interesting as a renewable source for bioethanol production which is
much easily degradable than other lignocellulosic substrates. Newertheless, the most
promising new applications of biotechnology for coversions of sugar beet shreds into high-
value products seem to be directed towards development of products in pharmaceutical and
nanotechnology sectors such as dietary fiber and nanofiber and pharmacologically active
compounds.
