Starch and flour from defective rice kernels and their physicochemical properties

摘要

The objective of this study was to evaluate the extraction yield and the physicochemical, crystallinity and thermal properties of starch from rice kernels with different types of defects. The defects present in milled rice kernels were separated and classified into five groups: Yellow, Damaged 1, Damaged 2, Red-Streaked and Chalky & Immature. Starch was isolated from the defective kernels, kernels without defects (Non-defective), and original samples (from the industrial electronics selector). The Yellow, Damaged 1 and Chalky & Immature kernels presented higher extraction yield of starch (approximately 66%) as compared to Non-defective kernels (60.1%). The starch from kernels with and without defects differed in pasting properties, indicating that the defects affect the quality of the starch; however, major differences were also observed in the flour. Starches isolated from defective kernels had higher pasting temperatures, peak viscosity and final viscosity than the starches of Non-defective kernels, with the exception of the starch of Red-Streaked kernels, which had a lower peak viscosity and final viscosity and higher breakdown characteristics.