The influence of acid hydrolysis followed by autoclaving-cooling on physical properties and resistant starch of purple sweet potato (Ipomea batatas L.) flour

In this study influence of acid hydrolysis using HCl 2% followed by autoclaving-cooling at 121°C for 15 minutes and cooled at 5°C for 72 hours with two repetition cycles on resistant starch of purple sweet potato flour were investigated and physical properties were analyzed. This treatment exhibited beneficial impacts of modified flour on resistant starch formation by 14.35%. Significant difference was exhibited between native and modified flour for ΔE value. Rapid visco analyzer was also used to determine pasting properties including peak viscocity, trough viscocity, breakdown, final viscosity, setback, and peak time where all of them except breakdown value were higher than the native one. Moreover, no signs of damage on the surface of native purple sweet potato flour were showed in micrograph of scanning electron microscopy. While autoclaving-cooling sample exhibited a rough structure as a result of the loss of its granular appearance and destroyed shape. This study also indicated a change of X-ray diffraction pattern from C-type to B-type caused by the modification treatment.