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

Abstract

This study aimed to develop a functional food ingredient by incorporating grape pomace extract into mushroom slices using both vacuum impregnation (VI) and simultaneous application of ultrasound assisted vacuum impregnation (VI+US) techniques with further air drying at 55, 65 and 75 °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.