Starch modified by natural fermentation in orange-fleshed sweet potato

Abstract

This study aims to modify starch via the spontaneous fermentation of orange-fleshed sweet potato for a period of 0, 4, 8, 12, 16, and 20 days and evaluates the effects of this process in this starch. In Brazil, this flour which is naturally fermented from manioc is described as “puba.” Thus, the results of “puba” from the orange-fleshed sweet potato ferment for 12 days show increases in the amylose content, luminosity, gelatinization enthalpy from Differential Scanning Calorimeter (DSC), final paste viscosity from Rapid Viscous Analyzer (RVA), and gel hardness but the water solubility and absorption (WSI and WAI) indexes are reduced. Using Scanning Electron Microscopy (SEM), the consumption of non-starchy materials and depressions on the surface of the granules resulting from the fermentation could be seen. The Fourier Transform Infrared (FT-IR) Spectroscopy, X-Ray Diffraction, and Nuclear Magnetic Resonance (NMR) Spectroscopy analyses show that no new functional groups are formed, and there are no changes in the crystallinity pattern (showing the same native CA- pattern) or molecular arrangement, respectively. Therefore, the sweet potato “puba” flour shows production viability due to the advantageous changes in its technological characteristics, as well as the potential to be studied for further food applications.