Effect of blanching time on physicochemical, nutritional properties, and functional properties of purple sweet potato flour

Abstract The study evaluated the effect of various blanching processes and blanching times on the physicochemical, nutritional content, and bioactive compounds of flour derived from purple sweet potatoes. The purple sweet potato was peeled, steam blanched, dried, and milled to produce purple sweet potato flour (PSPF). The pre-treatments applied were control (no blanching), 5-minute blanching, and 15-minute blanching. The PSPF sample was characterised for its physicochemical properties (carbohydrate, protein, moisture content, and total dietary fibre content), colour properties, total phenolic content (TPC), anthocyanin content, functional properties (water adsorption capacity, swelling power, and water solubility index), and pasting properties. The results showed that the blanching process and blanching time altered physicochemical characteristics, colour properties, bioactive compounds, and pasting properties. The longer time of blanching led to a sharper red index colour, higher swelling power, water absorption index, and water solubility index. A longer blanching time also resulted in higher TPC, greater anthocyanin content and higher pasting temperature and peak time viscosity.