Cellulose as a component of plant cell walls and as a food additive in confectioner

Abstract

A healthy diet is rich in dietary fibre (largely indigestible polysaccharides, most of which derive from plant cell walls). Cellulose is one of the main components of plant cell walls and a major contributor to human dietary fibre intake. It is a natural component of food-plants, and can also be added during commercial preparation of foodstuffs.

This project investigates the physico-chemical properties of various commercial sources of cellulose that have been empirically found to differ in palatability, especially ‘mouth feel’, as additives to confectionery. The aim was to explain why these seemingly similar celluloses behave so differently as food additives. Concurrently, I performed comparable studies on plant cell walls (prepared as alcohol-insoluble residue; AIR), sourced from various plant species and tissues. Potential differences between cellulose preparations could include (a) contaminating non-cellulosic polymers, (b) degree of oxidation, and (c) accessibility of cellulosic surfaces to neighbouring solutes.

(a) Contaminating non-cellulosic polymers: I performed various studies for chemical composition – digestion with α-amylase for analysis of starch content; washing with phenol followed by Ba(OH)2 hydrolysis for analysis of covalently bound proteins; assay of acetyl bromide-soluble lignin and hydrolysis with trifluoroacetic acid and H2SO4 (followed by thin-layer chromatography) for analysis of hemicellulose relative to cellulose content. These assays did not reveal major differences between the various commercial cellulose samples – all were relatively pure cellulose. Naturally, the AIR preparations were more diverse in chemical composition, containing all the non-cellulose polymers studied (starch, proteins, lignin, hemicelluloses and pectin).