Development of a high-performance anion-exchange chromatography with pulsed amperometric detection based profiling approach to analyze (hetero)mannans.

Structural analysis of polysaccharides is essential for understanding their functions in the plant and their technofunctional properties in food. Therefore, a profiling approach for analyzing mannans was developed. First, enzymatically generated standard compounds representing glucomannan and galactomannan structural units were produced. Five different glucomannooligosaccharides with a degree of polymerization (DP) of 2-4 were obtained from konjac meal and four different galactomannooligosaccharides with a DP of 3-8 from locust bean gum. A combination of different liquid chromatography methods was used for their purification, followed by spectroscopic identification. Having these and additional commercially available standard compounds on hand, an analytical approach for (hetero) mannan profiling was developed and validated. This assay is based on enzymatic hydrolysis of the sample material by a specific mannanase and a semi-quantitative determination of the released oligosaccharides by high-performance anion-exchange chromatography and pulsed amperometric detection. If required, additional mass spectrometric detection can be performed. (Hetero) mannooligosaccharides released from a plant sample can thus be detected, allowing for the classification of the mannan type as demonstrated by application of the developed assay on plant materials including coffee beans, copra meal, and blackcurrant seeds.