Study of the Drying Kinetics of “Granny

Th e drying characteristics of “Granny Smith ” apples were analysed using a tunnel drier at diff erent temperatures and diff erent pre-treatments. „Granny Smith “ apples were cut into rectangle-shaped samples 20x20x5 mm in size. Th e drying temperatures for non-treated samples varied from 50ºC to 80ºC at airfl ow velocity of 2.8 m s-1. Prior to drying at 60ºC, the samples were pre-treated either thermally or chemically, or both (blanching in hot water, steam blanching, blanching in hot 0.6 % CaCl2 solution, freezing to temperature of –18ºC and dipping in 1 % ascorbic acid solution). Th e aim of the study was to get dried apples with approximately 10 % water content, with good texture, rehydration capability and colour quality. Th e eff ect of the temperatures and pre-treatments on the quality of dried apple samples was determined on the basis of colour and volume changes and reconstitution characteristics. Th e kinetic equations were estimated using exponential mathematical model. Th e results of the estimation exhibited correspondence to the experimental results. Th e best results for non-treated apple samples: shorter drying time