Methods of Estimating Carbohydrates II. The Estimation of Starch in Plant Material: The use of Taka-diastase

Abstract

1. The Sachsse method of estimating starch is unreliable in the case of plant material; not only does the presence of pentosans falsify the results as pentoses are formed during the hydrolysis, but actual destruction of dextrose occurs during the prolonged treatment with dilute acid. 2. O'Sullivan's method gives low results owing to the loss of dextrin which occurs during the purification of the solution after the conversion by diastase. 3. A method is described for estimating starch based on the use of taka-diastase; under suitable conditions this converts the starch into maltose and dextrose only and no loss of these sugars occurs when the solution is treated with clearing agents such as basic lead acetate. 4. The necessity of removing substances soluble in water, such as gums, etc., which are optically active and thus cause error in the estimation of starch in plant material is emphasised. Special care is also necessary in sampling.