Effect of Vacuum Impregnation on Drying Kinetics and Selected Quality Factors of Apple Cubes.

The possibility of using the vacuum impregnation as a pretreatment before drying apple cubes was investigated. The impregnation was carried out for 4.5 min with the vacuum pressure of 0.01 MPa. The sucrose solution or a mixture of sucrose and the citric acid were used as infiltration liquids. Apple cubes were dried by convective drying (CD) (at temperature of 50 and 70 °C) or microwave-vacuum drying (MVD) (at power of microwaves 120 and 480 W). The drying kinetics was determined and quality factors (anti-oxidant activity, mechanical-rheological properties and colour changes) were analysed. Studies proved that the vacuum impregnation causes increasing of the drying dynamics (12.50-28.57 % during CD and 12.50-18.48 % during MVD). All impregnated apples were darker, yellower and susceptible for deformation or cutting than nonimpregnated. The highest level of anti-oxidant activity was observed when two-component impregnant before MVD by power of 480 W was used. [ABSTRACT FROM AUTHOR]