Production of phenolic enriched mushroom powder as affected by impregnation method and air drying temperature

This study aimed to develop a functional food ingredient by incorporating grape pomace extract into mushroom slices using both vacuum impregnation (VD and simultaneous application of ultrasound assisted vacuum impregnation (VI+ US) techniques with further air drying at 55, 65 and 75 degrees C. Drying kinetics of processes as well as bioactive compounds and physical properties of mushroom powders belonging to VI and VI + US treatments were assessed and compared with non-treated (N-T) samples. The activation energies of drying for VI (27.05 kJ mol(-1)) and VI+ US (16.24 kJ mol(-1)) treatments were found significantly lower than N-T (43.42 kJ mol(-1)) samples, and VI +US samples exhibited highest total phenolic and total flavonoid contents with highest antioxidant capacity values. Physical properties of the mushroom powders were affected by both impregnation techniques and air-drying temperatures. Impregnation treatments increased D[3,2] values (surface area mean) of the samples dried at higher temperatures, and the ultrasound application resulted in the highest values. Both VI and VI+ US treatments improved flowability (Carr index) compared to N-T samples. The highest oil and water holding capacity values were determined in VI +US samples while sole VI treatment revealed lowest water holding capacity.