|dc.description.abstract||For the production of biotechnological materials, sustainable resources are required
that do not compete with the food supply. Such a material is the cheap and plentiful
sugar beet pulp (SBP), a cell-wall-rich by-product from the sugar industry. The
long-term goal of this study is to improve effective waste management of SBP and its
application as a carbohydrate-rich material.
I have characterised SBP and its derived biotechnological product, Curran®, by
investigating the chemical composition, the constituent polysaccharides’ molecular
mass and the product’s potential to interact with water. Curran® has valuable
rheological properties and thus numerous potential industrial uses, for example as an
additive in paints. Viscosity of Curran® is considered the most significant parameter
to distinguish between high- and low-value products (high viscosity is usually
regarded as being of higher value). Therefore, a wide range of different viscosity
experimental Currans® (eC) were selected for this project.
I hypothesised that the composition, as well as polysaccharides’ molecular mass,
have a significant influence on viscosity. Results from this project showed that eC are
a changed cell wall polymer network, comprising essentially all the cellulose, much of
the hemicellulose but only low levels of pectins.
I further tested whether the molecular mass of hemicellulosic and pectic
polysaccharides in eC affects viscosity of the product. All hemicelluloses and pectins
in eC showed decreased molecular mass compared with the polysaccharides in SBP.
In addition, high-viscosity eC contained the smallest pectic polysaccharides. This led
to the conclusion that viscosity increases with decreasing molecular mass of the
I finally investigated the accessibility of hydroxyl (–OH) groups in the polysaccharide
network of eC products and other carbohydrate samples. The –OH group availability
is an important factor for the interaction of eC with other industrial ingredients. Hence,
the availability of –OH groups was hypothesised to correlate with viscosity of the eC
products. This work established an easy, but sensitive, method for the relative
quantification of available –OH groups in different carbohydrate materials such as
paper, xyloglucan, SBP and eC products. The method is based on the quantification
of 3H remaining bound to carbohydrate samples after removal of 3H2O by desiccation.
The percentage of 3H retained and hence availability of –OH groups in eC products
increased with increasing viscosity. Greater availability of –OH groups might increase
the interaction of eC particles with each other and water molecules which leads to
enhanced viscosity. Furthermore, the addition of these eC or Curran® products to
paints may benefit the paint’s properties (such as cracking resistance in hot or cold
The findings of this thesis contribute to an improved understanding of Curran’s®
rheological properties and may lead to an optimised production of Curran®. In future,
this might inform strategies of adding Curran® to a wide range of products and thereby
increase the use of “waste” for biobased materials.||en