Cassava Starch

The two products come from the same root and are routinely confused, but they are made differently and behave differently. Cassava flour is the whole peeled root, dried and milled: it retains the root’s fibre, protein, and minerals along with its starch, and it carries the colour and flavour that come with them. Cassava starch is the starch alone, washed free of everything else by a wet process, and it is white, bland, and functionally consistent.

The difference is not one of grade or refinement level within a single product. They are separate products, made on different equipment, sold to different buyers, at different prices, for different purposes — and a recipe or formulation calling for one will generally fail with the other.

Cassava starch extraction is a race with the raw material. Roots begin deteriorating within days of lifting, and a deteriorated root gives less starch and gives it dirtier, so the factory schedule is dictated by the delivery, not the other way round. Roots are washed and peeled, rasped to a fine mash that ruptures the cells, and the starch is washed out of the fibrous residue.

The starch milk is then separated from the solubles, refined through repeated washing, dewatered, and dried — commonly by flash drying, which is fast enough to avoid damaging granules that are already free of their protective cell walls. Two residual streams accumulate: peel, taken off at the front of the line, and the fibrous pulp left after the starch is washed out. Both are handled as residuals with feed and other uses rather than as products the factory is run to make.

Cassava starch pastes at a comparatively low temperature to a clear, cohesive, notably bland gel. The neutral flavour is a genuine commercial advantage — there is no cereal note to mask — and the clarity suits applications where the thickener must not be seen. Its cohesive, somewhat stringy texture is prized in some food traditions and engineered away in others.

• Food — thickening, texturising, and the base for tapioca pearls and snacks
• Industrial — paper and board manufacture
• Industrial — adhesives, textile sizing, and binders
• Feedstock — native starch converted into modified starches and sweeteners
• Energy — fermentation substrate for ethanol

As with other native starches, the paste is not robust to prolonged heat, shear, and acid, so a large share of production is modified before use. Native and modified cassava starches are separate commercial goods, and permitted modifications are a matter for food regulation in the market of use.

Buyers assess whiteness, starch purity, moisture, ash, residual fibre, and the absence of specks and off-odour — most of which are readings on how well the factory washed the starch and how fresh the roots were. Viscosity behaviour is specified where the application demands it. The product ships as a dry powder in bags, big bags, and bulk; it is hygroscopic and cakes in humid air, and like any fine organic powder in bulk handling it carries a dust explosion hazard.