Comparative study of the starch determination methods in cassava root and flours

Starch content of cassava tubers was determined with 8 methods; namely: (1) measurement in specific gravity of cassava roots, (2) measurement in degree baume of starch suspensions, (3) the polarimetric method, (4) the colorimetric method, (5) Fehling titratic method after hydrolysis with 0.3094 N HCl, (6) enzymatic method, (7) Fehling titratic method after hydrolysis with 25 % HCl and (8) HPLC method. The results indicated that the starch content obtained by using methods (1) and (2) were nearly the same and significantly higher than the results of the other methods (p=-0.01). The methods of (3), (4), (5) and (6) gave almost the same values. The starch content obtained by using methods (1) and (2) were nearly the same and significantly higher the results of the other methods (p=0.01). The methods of (3), (4), (5) and (6) gave almost the same values. The starch content obtained by using methods of (7) and (8) were lower than the other methods (p=0.01). Among the above methods, methods (1) and (2) had the lowest covarience of variation, thus these two methods gave the highest precision in determination of starch in cassava roots. Six methods; (3), (4), (5), (6), (7) and (8) were also used to determine the starch content in cassava flour. The results of methods (3), (4), (5) and (6) were not significant different and could be used alternately, whereas methods (7) and (8) gave the lowest starch content. In comparisions of the covariance of variation (CV) of individual methods of (3), (4), (5), (6), (7) and (8) in determination of the starch content in both cassava root and flours, the CV valve in the determination in cassava flour were lower than that in the cassava root. It might be suspected that these methods were more suitable for starch determinations in cassava flour than cassava root. Moreover the enzymatic method (6) was the best method attributed to the lowest CV.