Microwave‐Assisted Drying of Kiwifruit: Effects of Microwave Power on Functional Properties and Energy Consumption

ABSTRACT

This study investigated the effects of different microwave power levels (360, 540, 720, and 900 W) on the functional, physicochemical, and bioactive properties of kiwifruit powders, as well as energy consumption kinetics during drying. Power‐dependent color changes were observed: loss in greenness ( +a ) increased at 540 and 900 W, whereas +b and chroma values decreased at 900 W. HR values (1.10–1.22) indicated acceptable flowability across all treatments, with no significant differences in flow properties. Water activity (aw) reached its minimum at 720 W, while hygroscopicity peaked at this level. Water holding capacity (WHC) was highest at 720 W (5.52 g water/g), whereas oil holding capacity (OHC) (4.25 g oil/g) and water solubility index (WSI) (57.43%) peaked at 900 W. Total phenolic content (TPC) increased up to 720 W (1132.5 mg GAE/100 g) and remained statistically unchanged at 900 W. DPPH activity showed no significant difference between 720 and 900 W, while FRAP reached its maximum at 900 W (38.63 μmol TE/g). Energy analysis revealed that higher powers (720–900 W) produced elevated SMER values initially due to rapid moisture removal. However, SEC increased sharply in later drying stages, particularly at 900 W, reducing energy efficiency. Overall, 720 W favored several quality parameters, whereas 540 W offered a better energy‐efficiency profile. Since no single power level was superior across all parameters, balancing product quality and energy performance is essential for kiwifruit powder production.