Influence of natural fermentation and drying conditions on the physicochemical characteristics of cassava starch

The physicochemical characteristics of cassava starches sampled at a pilot plant in Colombia during fermentation and drying processes were determined in relation to their ability for making specific bread-like products that inflate during baking. Nitrogen compounds and non-starch polysaccharides are minor components which were unlikely to be involved in the baking expansion property of fermented cassava starch. Thirty percent of the lactic acid synthesised during the fermentation step was not recovered after sun-drying whereas it remained constant when oven-dried. The crystalline structure of starch was not changed by the fermentation and drying processes whereas the behaviour of starch polysaccharides in water was dramatically modified. This behaviour seemed to be related to the baking expansion potential of cassava starches; the lower the intrinsic viscosity, the hot paste viscosities and the hydrodynamic volumes of the starchy components, the higher the baking expansion ability. These results suggest the occurrence of an oxidative modification of starch molecules, such as depolymerisation, due to the joint action of fermentation and sun-drying.