Quality assessment of freeze- and convective dried plum varieties

Abstract

This paper deals with a comparison between two different drying processes. Hot-air and a vacuum-freeze drying processes were used for drying samples of plum (Prunus domestica L.) varieties (' Cacanska lepotica ', 'Cacanska rana ' and 'President '). The main objective of our research was to analyse and simulate the change of the quality parameters formed during dehydration by comparing two known drying procedures convective dehydration and lyophilisation. The study shows the drying kinetics of the two drying methods, and examines some special parameters which characterize the quality of dried products, including the microstructure, rehydration, and texture. The shape of cell structure was determined by electro-microscope. Thin layer drying model (third-degree polynomial) were applied for prediction of the freeze drying process. For model evaluation R: (coefficient of determination) was calculated. The model estimates showed a good agreement with experimental data. The highest values of hardness and rehydration were found freeze dried plum varieties.