Physicochemical properties of encapsulated purple sweet potato extract; effect of maltodextrin concentration, and microwave drying power

Abstract

Purple sweet potato (PSP) is rich with anthocyanin and has a great potential as natural food colorant. In this study, investigation on the effect of maltodextrin (MD, DE 4.0–7.0) concentration as wall material and various microwave drying powers towards physicochemical properties of microwave assisted encapsulation of purple sweet potato extract (PSPE) has been conducted. The effects of microwave power (550W and 330W) and MD concentration (20%, 25%, and 30%) were analysed for moisture content, water activity, colour, and total monomeric anthocyanin content (TMA). Both moisture content and water activity of the encapsulated PSPE were significantly decreased (p <0.05) as the MD concentration increased at 20% and 30%. With respect of anthocyanin content, increasing of MD concentration at 20% and 30% showed a statistically significant reduction (p<0.05). PSPA with 20% concentration gave the highest TMA at both microwave drying power of 330W and 550W, with 385.93 ± 10.81mg/L and 419.28 ± 10.89mg/L respectively. However, moisture content, water activity, colour, and TMA were not significantly different with the changing of microwave drying power.