Fate of mucilage cell wall polysaccharides during coffee fermentation

Effects of a 20-h fermentation on cell wall polysaccharides from the mucila ge of pulped coffee beans were examined and compared to those of unfermente d beans, on alcohol insoluble residues (AIRs), their hot-water-soluble crud e pectic substances (PECTs), and their hot-water-insoluble residues (RESs). Yields and compositions were very similar: AIRs, which consisted of simila r to 30% highly methylated pectic substances, similar to9% cellulose, and s imilar to 15% neutral noncellulosic polysaccharides, exhibited no apparent degradation. However, PECTs from fermented beans were shown to have undergo ne a slight reduction of their intrinsic viscosity and weight-average molec ular weight by capillary viscosimetry and high-performance size-exclusion c hromatography. After fermentation, hot-water-insoluble pectic substances of RES exhibited partial de-esterification. Removal of coffee bean mucilage b y natural fermentation seems to result from a restricted pectolysis, the me chanism of which remains to be elucidated.