A Comparative Study of the Structures, Crystallinities, Miller Indices, Crystal Parameters, and Particle Sizes of Microwave- and Saline Water-Treated Cassava Starch

The structures, crystallinities, Miller indices, and particle sizes of cassava treated with microwave radiation or saline water were analysed and compared. Cassava was milled to sizes of 100 to 120 mesh and then dried under solar radiation for several days. The first set of substrates was treated by microwave radiation at 300 W for 10, 20, or 30 min or at 1000 W for 8 min. The second set of substrates was immersed in saline water for 5 days at salt concentrations of 3.43% or 10% (w/w). The treated substrates were characterised by x-ray diffraction, Fourier transform infra-red spectroscopy, and scanning electron microscopy, and the results were compared with the characteristics of the native substrate. There were significant differences in the characteristics of the microwave- and saline water-treated cassava. Crystallinities of the microwave-treated substrates were lower than those of the saline water-treated samples. A large shift (change in 2θ) in the diffraction peaks was observed for the treated substrates as compared with the native substrate. Examination of the surface morphology suggested that saline water enabled the dissolution and elimination of the undesirable fibres in the substrate; this was not observed for the microwave-treated substrate.