Tapioca starch comes from the roots of the cassava plant. The cassava plant has different names depending on the region. In North America and Europe, the roots are called cassava, while in other regions, it is called yucca, mandioca, manioca, tapioca, cassada, or cassava. The plant belongs to the spurge family, and it was previously described as two edible species based on the presence of high and low cyanide contents in roots. However, they are now classified as the same species, Manihot esculenta.
Cassava is an easy-to-grow shrubby crop that can grow in many soil types, including infertile or acidic soil. It needs little water and can survive droughts. To grow more cassava, a piece of stem (called a stake) is planted in the ground, ideally vertically. Good-quality stakes are taken from mature plants and spaced about 100 cm apart. Plants can reach 1-5 meters in height and are ready for harvest in 8-18 months. The roots, which are the edible part, are just below the surface and should be harvested after 10-12 months. It’s important to harvest at the right time, indicated by the plant’s harvest index, to maximize root yield and starch content. To harvest, cut the stem and pull the roots from the ground. The plant tops can be used for replanting, and the roots are taken to the processing factory.
The amount of cassava roots produced depends on different factors, like the type of cassava, the quality of the soil, the weather, and how well the crop is cared for (e.g. using fertilizer and weed control). Although cassava requires low maintenance, taking good care of it can result in high yields. Cassava is usually grown on land that isn’t good for other crops, so it’s not often rotated. In some areas, the farming practices don’t provide enough nutrients, so fertilizer is needed to get the best yield. Usually, 5 to 20 metric tons of cassava roots are produced per acre (12-48 T/hectare).
Mature cassava roots come in different shapes and sizes, ranging from 3 to 15 centimeters in diameter, depending on the variety, age, and growth conditions. The color of the outer peel can be white or dark brown. When you look at a cross-section of the root, you can see two main parts: the peel and the central pith. The peel has two layers, the outermost layer called the periderm and the inner layer called the cortex, which contains different types of tissue. The central pith of the root is where the starch is stored, and it is made up of cambium and parenchyma tissue and xylem vessels.
Mature cassava roots contain 60-70% water, 30-35% carbohydrate, 1-2% fat, 1-2% fiber, and 1-2% protein, along with small amounts of vitamins and minerals. The starch content of roots varies from 15-33% depending on the climate and when they are harvested. The maximum starch content is at the end of the rainy season. Cassava is not a good source of protein, vitamins, and minerals, but it is used as a staple food in many areas because it is a good source of energy.
It is important to consider the toxicity of cassava when using it for human or animal consumption. Cassava plants contain cyanogenic glucosides, which can release hydrogen cyanide when the plant is damaged. The amount of cyanide in cassava roots varies depending on various factors. The cyanide content is highest in the peel, rather than in the starchy tissue of the root. There are three types of cassava: low toxic (sweet), medium toxic, and high toxic (bitter). Sweet cassava is preferred for direct consumption, while bitter cassava is used for industrial products. Proper processing methods are necessary to effectively detoxify cassava and produce safe products.