Tannin levels in cassava,a comparison of methods of analysis

Low levels of tannins (proanthocyanidins) have been detected in dried cassava (Manihot esculenta Crantz) samples using standard methods of analysis based on extraction procedures. A direct vanillin assay method was compared with other direct methods of analysis based on acid hydrolysis and protein precipitation. The specificity of the methods is discussed in relation to the levels of tannins detected and their potential biological activity in freeze dried fresh and dried/processed cassava samples. The results are discussed with respect to the amount of indigestible material present in the samples. The results of these experiments indicate that tannins present in dried/processed cassava products may be a factor limiting their nutritional value.