Microstructural Characteristics of Dried Carrot Pieces and Real Time Observations during Their Exposure to Moisture

Abstract

The effects of different drying methods on the cellular structure of carrots were examined. Carrots were dried by vacuum drying, freeze drying and oven drying in combination with microwave pre-drying. Dried and fresh untreated samples were analysed by light microscopy and environmental scanning electron microscopy (ESEM). The cellular structure of vacuum dried as well as microwave pre-dried samples was found to be very different from that of fresh samples. Most, if not all, of the original microstructure was lost during drying with these techniques, though traces of original structure were preserved on external surfaces. Most of the original microstructure was preserved in the freeze dried carrot. ESEM was also used to observe the behaviour of the dried samples in an atmosphere of increasing humidity and showed that dried tissues did not regain their original cellular structure though some turgidity was regained by the freeze dried samples.