BACKGROUND An interesting approach to improve dried foods nutritional properties, functionality, and sensorial attributes, is by taking advantage of pre-treatments for incorporating components into the food matrix. Based on this, this work studied the incorporation of black carrot anthocyanins in apple tissue by using ethanol (concentrations 0-300 mL L-1) as a pre-treatment to ultrasound-assisted convective drying. Samples were pre-treated in acidified ethanol solutions, with and without anthocyanins, and then dried (50 degrees C, 1 m s(-1)) by convective and ultrasound-assisted convective (21.77 kHz, 20.5 kW m(-3)) drying. Both the drying process improvement and the obtained product properties were studied. RESULTS The anthocyanins did not influence the drying kinetics. In contrast, time reduction was > 50% by using both ethanol pre-treatments and ultrasound. Ethanol pre-treatments decr...

Different drying accelerators were studied to improve vegetable drying: acetone (AC), ethanol (ET), isopropanol (ISO) and acetic acid (AA). Pre-treatments were performed by immersion of pumpkin cylinders. Convective drying was performed at 40 degrees C and air velocity 1 m/s. Different aspects were evaluated: drying kinetics, structural changes (microstructure and macrostructure), thermal profile and viscoelastic and rehydration behaviours. The microstructure was modified by pre-treatments, being more pronounced with AC and AA. Thinner cell walls, changes on turgor and extraction of components and air were reported, affecting the mass transfer. Moreover, the microstructural changes reinforced anisotropy and also affected the macrostructure, changing the viscoelastic behaviour. All pre-treatments resulted in a super-diffusive behaviour, decreasing the drying time from 9% (ISO) to 22% (AC)...