Cassava and its Powdered Derivatives; Flour and Starch in Perspective

It serves another important purpose because of the uses of its derivatives. Cassava has many uses aside being use directly as food. Cassava can be converted into starch, flour, ethanol, chips, syrup etc. it is also used as animal feed because of its fiber content and as a biofuel component among others. These numerous derivatives make cassava very important as it can be used in the food, textile, pharmaceutical industries etc., in fact studies show that in every industry, cassava derivatives are used.

Most cassava derivatives can easily be distinguished from each other as ethanol is liquid, chips is in a solid form. However, the powdered property of cassava flour and cassava starch makes it very difficult for people to differentiate between the two. In many cases, the products have been interchanged for the end user. In this article we will differentiate between the two, that is, cassava starch and flour. Cassava starch and cassava flour have some physical properties that makes it difficult to differentiate, both of them are in a powdered form and are all in most cases white in color. But analyzing carefully you would realize that there are a lot of differences.

Processing cassava into starch is more sophisticated than flour. Therefore, the processing line for cassava starch has more equipment than the cassava flour even though some of the machines like flash dryers are used in both processing lines.

Processing cassava into flour is simpler. The fresh cassava roots are peeled and washed , this is sometimes done manually but for large scale production, machines are used. The washed tubers goes through the grating process where the tubers are cut into smaller pieces , then desanding takes place before it is pulverized into fine particles before going through the dewatering  unit to remove excess water content, then dried in the flashed dryer and finally sieved and packaged.

On the other hand, when processing cassava starch, the tubers are not peeled because the peel itself has some starch in them. Therefore, the tubers right from the field goes through the dry-cleaning units to clean the dirt and the husk, before it thoroughly washed. The cleaned tubers are then cut and mashed by the rasper and then goes through the desanding stage to remove the remaining dirt in the cassava slurry. The slurry moves to the sieving stage where fibre and other particles are removed in the cassava slurry, this is normally performed by the centrifuges, before it goes into the refining unit made up of the hydro cyclones which removes the insoluble substances such as proteins, fat and others from the cassava slurry. The pure slurry is then dewatered and dried into cassava starch.

Different processing methods and processing lines lead to different properties of cassava starch and cassava flour. With the cassava starch, impurities such as sand and other components such as fibre, protein, fat etc. are removed to obtain only starch, therefore it is pure white in colour and has no taste, this makes cassava starch hygroscopic and can be gelatinized and is hydrolysable. Furthermore, the toxicity of cassava is removed during processing due to the complicated processing process, making it non-toxic.

On the other hand, cassava flour contains fibre and other substances, so the colour of cassava flour is not as white as starch. Also, cassava flour still contains a little toxicity, especially the cassava flour produced through semi-automated processing. Therefore, cassava flour can not be eaten raw, however, the toxicity of cassava flour can be removed by cooking.

The difference in properties determine the different usages of cassava starch and cassava flour.

Cassava starch is a good industrial raw material because of its low non-starch impurity content, high viscosity, low gelatinization temperature, transparent and stable paste liquid, good film formation and strong permeability. It is widely used in food, beverage, candy, pharmaceutical, textile, paper and other industries.

Due to cassava starch’s high viscosity, it can be used as an adhesive. Its paste is clear, which is suitable for colouring with pigments, can also be used as a thickener, puffing machine, binder and stabilizer.

As for cassava flour, it is mainly used in the food industry. In African countries, cassava flour can be used as substitute for wheat flour for making baked goods. That is because, cassava flour contains fibre, and fibre can be used as a substitute for gluten to improve the texture of some baked goods. Meanwhile, cassava flour is increasingly used in a variety of foods such as bread, noodles, and pancakes.

Due to the demand for these products, it is imperative that we differentiate between the two to avoid loses. Especially when you cannot use flour for many things that cassava starch can be used for. Cassava root is basically made up of water, fibre, protein, cyanide, vitamins and the flesh. In simple terms, cassava starch is devoid of all the other components in the cassava tuber except the flesh, while the cassava flour is the powdered flesh that contains some of the other components like fibre and protein.

In Ghana, most varieties used for starch are the same used for Flour. Varieties like the Sika Bankye, Bankye Hemaa, Ampong Bankye, Otuahene Bankye, Capevars Bankye are all varieties suitable for both Starch and Flour but Sika and Capevars Bankye are the best varieties for producing starch as it has very high starch and less fibre content. Ampong Bankye is normally suitable for high quality cassava Flour than starch because it has more fibre content. Although the cost of producing or buying these raw material varieties for processing is the same, the cost in processing lines and the factory as well as its operations are not the same as the cost of the starch processing line and its operational cost is higher than that of Flour. Same goes for the price of starch being higher than that of flour, thus, an end user should always get detailed information about the two products in order to make the right preparations, get the right equipment and skills to produce the right product.

Industrialization is very important and in a developing sector in this part of the world. It is prudent that the right information is known by the stakeholder, so as to produce the best products for the local and international market. Also, knowing the difference would prevent the sales of wrong or interchanged products to the end user, as well as the wrong machines to the processor, thus bringing sanity and breeding trust and awareness in this seedling industry. The next time a stakeholder wants to go into processing cassava or buying processed cassava in a powdered form the above differences should not be refrained from for success to be assured.