Hemicelluloses

Hemicelluloses include non-starch polysaccharides such as (arabino)xylans, (glucurono)xylans, xyloglucans, (galacto)mannans, (galacto)glucomannans, and mixed-linked-beta-glucans. According to a generalized classification scheme, the dominant hemicelluloses in the primary cell wall of dicots are xyloglucans, whereas primary cell wall hemicelluloses of commelinid monocots are dominated by arabinoxylans. Mannans are widespread, but often less dominant quantitatively, for example in cereal grains. In certain plants or plant tissues, however, mannans also serve as reserve polysaccharides and are therefore found in large portions.

As these polymers largely differ in chemical details that determine their functionality including fermentability as a key characteristic in food and feed, we strive to understand the molecular assembly in the closest detail possible. Thus, we have developed and continue to develop profiling approaches for the described hemicelluloses to study structural elements that may affect both nutritional and technological functionality. These approaches are usually based on partial enzymatic or chemical degradation, followed by chromatography (ion, hydrophilic interaction, and reversed-phase chromatography) based separation in combination with several detection techniques including mass spectrometry and pulsed-amperometric detection. Labeling strategies are also of interest. Depending on the chemical structures, approaches to modify these versatile polymers are being developed.