Combined Smoking and Drying Kinetics of Retted Cassava Pulp and Effects on the Physicochemical and Pasting Properties of the Extracted Starch

Cooked paste of smoked-dried flour of retted cassava is the staple food of million people in West and Central Africa. The present study investigates the dynamics of combined smoking and drying on some physicochemical and functional properties of the flour and its derived starch. Fresh cassava tubers (variety 4115) were trimmed, retted, wrung, crushed, put into balls and then dried using three processes: traditional combined smoking and drying, electrical combined smoking and drying, and oven-drying. The drying processes did not significantly modify (p > 0.05) the proximate composition of samples neither their drying rates (0.19 h⁻¹ < k < 0.22 h⁻¹). A positive and significant correlation was shown between the drying constant k and the smoking constant k ₛ (p < 0.05). The colour of the oven-dried flour sample was clearer with the highest whiteness index (86.11 ± 0.76) than the flour from traditional and electrical combined smoking and drying processes (65.41 ± 4.35 and 68.18 ± 3.98, respectively). The peak viscosity and breakdown values of retted starch paste were significantly higher (p < 0.05) than that of the flour from which it originated. Meanwhile, the starch cold paste exhibited lower setback values and thus a lesser tendency to retrogradation when compared to retted flour gel. All this suggests that despite the relative instability of temperature in the traditional attic, it preserves, in comparable extent, the functional and nutritional values of cassava derivatives as electrical drying processes. Considering the functional use of the retted cassava for fufu preparation, smoked-dried starch is more suitable for cooking than oven-dried starch. In addition, the electrical combined smoking and drying process appeared as the best drying method, since the derived product has low tendency to retrogradation.