Dietary fibre in cocoa shell: characterisation of component polysaccharides

Polysaccharides were isolated from cocoa shells and characterised by compositional and linkage analysis. The polysaccharide types were diverse and included pectic polysaccharides (∼45%) which were made up of a heterogeneous mixture of rhamnogalacturonans with variable degrees of branching. Hemicelluloses (∼20%) consisted of a mixture of a fucosylated xyloglucan, galactoglucomannans, and glucuronoarabinoxylan. Cellulose accounted for ∼35% of the cell wall polysaccharides. The total dietary fibre content was approximately 40%, not as high as previous reports. This was attributed to the fact that previous studies have included a “Klason Lignin” fraction in estimates of fibre. A solid state NMR study of the cocoa shell “Klason Lignin” fraction provided evidence that it contained little if any lignin and presumably consisted principally of protein–Maillard–tannin complexes.