Impact of steam-heat-moisture treatment on structural and functional properties of cassava flour and starch

Abstract

In this study, moisture, steam-temperature and time conditions were optimised in relation to functional properties of cassava flour and starch. The optimal conditions for cassava flour were 15% moisture, 120 °C and 1 bar for 10 min and for cassava starch were 19% moisture, 120 °C and 1 bar for 20 min. Structural, physicochemical, viscoelastic and thermal characteristics of cassava flour and starch upon the optimal steam-heat-moisture treatments were examined Volume-based diameter (D(4.3)) of cassava flour granules reduced (107.87 to 42.94 μm) and cassava starch granules increased (17.67 to 50.88 μm) when subjected to optimal steam-heat-moisture treatments. The optimal steam-heat-moisture treatments had no effect on the crystal patterns of cassava flour and starch (A-type), nonetheless, relative crystallinity of cassava flour was increased (34 to 59%) and cassava starch was decreased (32 to 27%). Increments in swelling power (17.24 to 19.07 g/g) and peak viscosity (6377 and 7330 cP) and, reductions in solubility and loss factor (tanδ) were ensued by the optimal steam-heat-moisture treatment of cassava starch. Both optimal steam-heat-moisture treatments of cassava flour and starch had increased thermal stability but reduced breakdown viscosity, setback viscosity (528 to 230 cP and 1259 to 938 cP, respectively) and gelatinisation enthalpy.