Partial depolymerization of pectin by a photochemical reaction.

Complex heterogeneous polysaccharides that comprise pectin were partially depolymerized by a photochemical reaction using ultraviolet light in the presence of titanium dioxide catalyst. In a period of 6h at pH 7, this UV/TiO(2) process decreased the average molecular weight of pectin from 400kDa to 200kDa. The characterization of the partially depolymerized pectin, which was fractionated by size-exclusion chromatography, was performed by (1)H NMR spectroscopy, and the spectra obtained showed that the resulting oligosaccharides and polysaccharides maintained the intact core structure of pectin. The monosaccharide content and depolymerization profile were determined by high-performance anion-exchange chromatography coupled with pulsed amperometric detection. This controlled photochemical depolymerization technique might be useful for preparation of pectin oligosaccharides as an ingredient in food and pharmaceutical products.