Investigation of Modified Cellulose and Starch via Hydrolysis and Mass Spectrometry

Abstract: Starches and celluloses can be chemically modified in order to affect their physiochemical properties. Modification of these carbohydrate polymers entails derivatising their free hydroxyl groups with functional groups. Which properties are obtained depends on the nature of the functional groups as well as on how they are distributed throughout the polymeric structure of the carbohydrate. Unfortunately, the correlation between the distribution of modifications and the obtained properties is not fully understood. In order to facilitate the investigation of this correlation, new analytical tools are needed. Starch and cellulose are too large to be analysed by most conventional analysis techniques. In this thesis this problem was remedied by using hydrolysis (either acid hydrolysis or enzymatic hydrolysis) to form smaller molecules that are more easily analysed. The hydrolysates were then analysed by ESI-MS. LC-MS, HPAEC-PAD, SEC-RI and reducing-end determination were employed as well. Four modified polysaccharides were investigated: two modified starches (hydroxypropylated amylopectin potato starch and cationic amylopectin potato starch) and two modified celluloses (carboxymethyl cellulose and methyl cellulose). The information obtained on the hydrolysates could be utilised both in understanding the distribution of modifications in investigated compounds and in understanding of the function of the employed enzymes.