Application of Three Alternative Technologies (Spray Drying, Fluid Bed Drying And Freeze Drying) to Obtain Powdered Formulas from Plants with Antimicrobial Potential

Abstract

This study aims the application of three alternative drying technologies (spray drying, fluid bed and freeze drying) to evaporate and immobilize the bioactive components of plant hydrophilic extracts on different natural matrices. Three different powdered formulas were obtained from watery extracts , e.g. 15% leaves of Persian walnut (Juglans regia ), European Mistletoe (Viscum album) and white willow bark (Salix alba ),  mixed with three different matrices (maltodextrin, lactose and salt) in a weight ratio 90:10. The mixes were evaporated by three alternative methods (spray drying, fluid bed and freeze drying) to obtain powdered formulas. By UV-Vis spectrometry and FTIR spectroscopy there were monitored the phenolic derivatives and their stability comparing the concentration in the initial extract and after drying. The concentration of phenolic derivatives decreased differently after drying, depending on the technology and the matrix. The best results were obtained for willow extract on salt, using spray drying technology, with recovery rates above 50%. The behaviour of the matrices was different during the drying process: the most reliable was maltodextrin used in spray drying and salt, used in fluid bed drying. By freeze drying, lactose and salt gave best results, but this technology was considered more expensive. Finally, the best procedure was found to be spray drying, due to its rapidity and the continuity of drying for a long period of time, being the most economic, while freeze drying assured reliable composition by slow vaporization process at low temperatures. The willow formula proved to be the most concentrated in phenolics and reccomended to be used as biodesinfectant.