ANNOUNCEMENT
Final Examination for the Degree of MSc
YIKAI REN

Examining Committee
Dr. Lisa Duizer, Chair
Dr. Douglas Goff, Advisor
Dr. Steve Cui, Advisory Committee Member
Dr. Massimo Marcone, Department Examiner

TITLE: Development of Natural Binders Based on Agricultural By-Products to be Applied in the Landscaping Industry

ABSTRACT: An alkaline extraction method was applied to extract polysaccharides from agricultural by-products: wheat bran (WB), corn fiber (CF), and okara, in order to substitute psyllium in novel binders applied in the landscape industry. Physicochemical and molecular characterizations indicated WB had better gelling potentials than CF and okara, with a higher molecular weight (MW), higher intrinsic viscosities (IV), and better viscoelastic properties. An extrusion process was applied to further improve the binding and gelling properties of WB. Results showed WB extrudates had a great increase (more than 100%) in soluble dietary fiber (SDF) content, as well as higher apparent viscosities and MW after extrusion. Alkaline pretreatment before extrusion exhibited positive effects on rheological and molecular properties, while cellulase pretreatment showed negative effects. Rainfall simulation test (RST) approach was applied to evaluate the rainfall-erosion resistance capability of modified binders and compare them to psyllium-based formulas. Fly ash addition (2%) could greatly reduce the solid loss (SL) in RST. WB and modified WB fibers did show much better SL results than CF and okara, although thet did not achieve the level of psyllium-based binders. Occasionally, yellow mustard gum (YMG) was also tested in RST. However, YMG exhibited much better binding potentials than WB, which had similar SL results to the control and was even better with fly ash added. Future work could be focused on the utilization and modification of yellow mustard bran, as well as the working mechanism of YMG in binder aggregates.