This work focused on the study of the physicochemical changes that take place during the fermentation of cassava starch for stepping times of 15–90 days. SEM studies on starch showed special attack while X‐ray diffraction analysis showed that cassava starch is mainly formed by amylopectin and that the acidification process produce significant structural changes in amylose and amylopectin as a function of the steeping time. Module Differential Scanning Calorimetry analysis showed that the acidification process produces an increase in the peak gelatinization for particular steeping times that are directly associated with changes in the acid condition of the samples and re‐crystallization process. Thermogravimetric analysis showed the non‐intentional contamination of the tanks due to the increase in the residue for long steeping times. The periodic reproduction of bacteria in the reservoir govern the changes in the pasting properties of the acid starch.