Solution NMR Spectroscopy of Food Polysaccharides

Many polysaccharides are allowed for direct food use, where they serve a number of useful functions including dietary fiber, bulking agent, thickener, encapsulant, gelling agent, foam and emulsion stabilizer, protective colloid, emulsifier and suspending agent, adhesive and binder, flocculant, swelling agent, film/coat former, or syneresis inhibitor. Many of these polysaccharides have complex structures or are mixtures with different components. Over the years, NMR has been a premiere technique for characterizing these materials. NMR characterization can help identify the materials in question, quantify the different functional groups present, and detect minor components and impurities. Above all, the high resolution achieved in solution NMR can provide detailed structural information on composition, sequence distribution, substitution pattern, and molecular weights (in some cases) for individual polysaccharides. Concurrent application of other analytical techniques, such as methylation, esterification, fractionation, mass spectrometry, and chromatographic methods, has enabled structural information on even complex polysaccharides or mixtures to be obtained. In this article a review is given of the solution NMR of food polysaccharides, with emphasis on papers published in the past 20 years. Included in the review is a survey of 21 common food polysaccharides, the current understanding of their structures, and the techniques used for their determination.