PNNL-13501 - Pacific Northwest National Laboratory

Figure 3. 13 C NMR spectrum of corn fiber hydrolysate,
showing α- and β-anomeric mixtures of arabinose (A),
galactose (Ga), xylose (X), and glucose (G)
magnetic field. The hemicellulose was found to contain
no detectable sterol/lipid oil components as expected, but
did contain detectable carboxyl groups. The solid-state
NMR spectroscopic method is useful for direct analysis of
residual protein in the mixtures, and for analysis of
residual carbohydrate in the extracted source corn fiber.
The results of this study include the successful
measurement of fiber hydrolysis rates and byproduct
formation, the identification of optimal hydrolysis
conditions, and measurement of kinetics of both corn
fiber and model disaccharide systems. This capability
development provides the starting point for the
development of economical sugar and neutraceutical
production.
Summary and Conclusions
Kinetics of hydolysis of a series of oligomeric sugars
were carried out to optimize reaction conditions for
minimal byproduct and maximum monomeric sugar
yields. Accurate corn fiber hydrolysis kinetics
demonstrated clean sugar production. The relative rate of
production of sugars followed the trend arabinose >>
xylose >> glucose >> galactose, and the rates of
hydrolysis of disaccharides demonstrated the trend
arabinobiose >> xylobiose > > cellobiose. Since the
homogeneous liquid phase hydrolysis of cellobiose is
relatively rapid, the very slow rate of hydrolysis of
cellulose reflects the well-known structural inaccessibility
of this material. The kinetic methods developed here for
disaccharides, and applied to wet milled corn fiber
provide support for scale-up design of commercial
carbohydrate extraction.
The results of the work serve to define the response of
categories of saccharide bonds to hydrolysis. Solid-state
NMR spectroscopy was also used to determine the
components of corn fiber derived hemicellulose, as well
as wet milled corn fiber.
Separations and Conversions 423