Biochemically modified polysaccharides from leguminous plants with versatile properties for industrial applications

Galactomannans are polysaccharides with a unique mannose-to-galactose ratio (M/G), which influences their properties. In this thesis, a quantification method for sugar diastereomers in galactomannans was developed, exploiting the fragmentation pathways of mannose and galactose in MS analyses. The spectra of commercially available galactose and mannose display the same fragments, but significant differences in their intensities. Mixtures of mannose and galactose have been analysed to evaluate the applicability of this method for quantification aims. The relative intensities can be deconvoluted, leading to a reliable quantification. The method has been applied to the quantification of hydrolysis products to evaluate susceptibility to different conditions. In addition, different galactomannans have been oxidised, generating structured and stable hydrogels. Upon lyophilisation, aerogels were generated, capable of uptaking solutions. Analyses by stability assays, MS, NMR and FT-IR demonstrate that the oxidation leads to the formation of carbonyl and carboxyl groups from hydroxyls and subsequent establishment of hemiacetal and ester bonds, cross-linking the gels. Fenugreek-based materials are more structured and stable compared to other aerogels, which is likely due to the higher amount of galactose units present in fenugreek gum and, therefore, to more extensive cross-linking of the resulting elastic gel. Actives have been absorbed into aerogels. The release of polymyxin B and nisin were evaluated against bacterial strains. Protease and lipase release was evaluated in solution by monitoring the increase in protein concentration and enzymatic activity. The analyses performed suggest that these aerogels represent versatile bio-compatible delivery systems and could be employed for industrial applications.submitted by Erika PonziniUniversität Linz, Dissertation, 2018OeBB(VLID)275142