THERMAL DRYING OF BIOMATERIALS WITH POROUS CARRIERS

Thermal drying of bioproducts often leads to a significant deteriorati on of product quality. One of the simplest methods for better quality retention of thermosensitive materials is drying of the materials in a mixture with porous carriers. In order to determine the effect of car riers presence on the mechanism of dehydration process a set of experi ments was carried out in a laboratory vibrofluidized bed dryer. The ex periments were performed for three different carriers (wheat bran, gro und rape and flour). Baker's yeast was taken as an example of a sensit ive material. The effect of following parameters on degradation proces ses was analysed: concentration and kind of a carrier, temperature and flowrate of inlet air and frequency of a vibrated bed. The analysis o f the results proves that temperature of inlet air and kind and concen tration of a carrier are the most important factors affecting final pr oduct quality. The results show that the main effect of a carrier's pr esence on quality retention comprises changes of a structure of labile material. Sorptional properties of the carrier are less important. In second part of the work dehumidified air was applied as a drying agen t to enhance quality retention of biomaterials. Results obtained are e ncouraging, however this method requires further research.