Quality control of cassava products

Cassava

Quality control of cassava products

In the processing of cassava, questions naturally arise regarding efficiency and output; moreover, in selling the product the determination of quality becomes important. These problems can only be resolved by qualitative and quantitative study of the composition of the raw materials and the properties of the finished products. The financial return, especially in large factories, will depend to a certain degree on such control analyses of cassava products, which in a way are actually part of the processing itself.

Analysis of basic materials

The two important basic materials requiring analysis are the cassava roots and the water used in cassava processing. The best practical qualitative test of these materials consists in reproducing the whole process on a small scale and judging the resulting flour by comparing it with a standard sample or by analysing it according to the methods described farther on. In fact, for judging the suitability of the water available, small-scale processing is the only test of practical value.

Apart from this, since cassava starch is the substance to be isolated, a determination of the starch content in both the fresh roots and the pulp remaining after rasping and wet-screening is necessary for control of the efficiency of the process and in particular for determination of the rasping effect.

Finally, tests for the presence of hydrocyanic acid are necessary owing to the important food uses of cassava products.

A random sample of, say, 10 kg of cassava is thoroughly washed to remove the cork layer; then either the whole or the peeled roots are grated or ground. The pulp is washed out over 50-mesh bronze gauze and the flour milk obtained over 260-mesh gauze. When the suspension reaches 3º Brix (approximately 35 g of dry starch per litre), it is left to settle for four hours. The top liquid is then decanted, and water is added to the settled starch to make a slurry of 10° Brix, which is strained over 260-mesh gauze and left to settle for the second time. After decanting, the starch is mixed with water to a thick suspension (45° Brix) and filtered on a Buchner funnel under vacuum. The moist starch is dried in an oven, preferably in circulating air, commencing at a temperature of 50°C, and concluding at 60°C.

The dried starch is sieved through silk before examination.