To find biocatalyst allowing depolymerization of new polysaccharides, one needs to get a sensitive and well adapted method to a screening program. This led us to compare biochemical methods of detection of the depolymerization. Currently used methods such as reducing sugars assays, double bond monitoring or molecular weight determination were tested to follow the kinetic of depolymerization with different enzyme / polysaccharide couples. The range of concentrations of assorted enzymes allowed us to identify the most sensitive and appropriate method to detect polysaccharide degradation. Reducing sugars assays are quantitative, sensitive and almost usable with all kind of polysaccharide but some compounds may interfere with them. When polysaccharide is bearing charges, agarose gel electrophoresis, although being a qualitative assay is as sensitive as high performance size exclusion chromatography analysis, easy to handle, quite high-throughput and thus preferred.