DRY COATING PROCESS USING POLYSACCHARIDES IN A PAN COATING SYSTEM L. Bilancetti 1 , C. Loisel 1 , F. Depypere 2 , K. Dewettinck 2 , J.G. Pieters 3 , D. Poncelet 1 1. ENITIAA - GPA, Rue de la Géraudiére, F-44322 Nantes Cedex 03, France; 2. Food Technology and Engineering and 3. Biosystems Engineering, Ghent University, Belgium. Abstract Coating of inert pellets of microcrystalline cellulose with modified starches by the dry powder coating technique was investigated, as an alternative to organic- and aqueous-based coatings. The coating process has been conducted in a Pan coater and the coating formulation is divided into two components, a powder polymer and a liquid plasticizer. The experiments carried out have shown high coating process efficiency. The best coating results were obtained using particles smaller than 50µm and having a polygonal shape. The dry coating technique has shown a reduction of processing time compared to standard coating techniques. SEM analysis has shown uniform coating shell thickness onto pellets without presence of coalescences in processes conducted at room temperature. Confocal Laser Scanning Microscopy (CLSM) was used to characterize the dry coated particles in order to measure coating quality and thickness. A protocol for dry coated pellets characterization has been set up. Results obtained by CLSM have demonstrated an effective increase in coating thickness with increasing coating level. 1. INTRODUCTION The principle of coating particles is used in the pharmaceutical field to enhance drug stability, avoiding drug degradation by oxygen, moisture, light and taste masking. In the food industry too, the coating technology is frequently used to separate ingredients from their environment (water, acid, oxygen, other food ingredients), which may be detrimental to the uncoated material or the food itself. It could be used to stabilize ingredients during processing (heat, pressure, moisture), to impart controlled release (during processing, storage or consumption), to change physical characteristics of the original material by reducing the hygroscopicity or improve flowability and compression properties, reducing dustiness or modifying density [1,2]. In the traditional coating, the process consists of spraying a coating material solution on pellets. In case of organic-solvent based process, solvent has to be recovered to avoid pollution, leading to an important overcost. Coating processes with aqueous dispersions are time and energy consuming [3] as a result of the low concentration of coating polymer and large amounts of water to be evaporated. In the last decade coating with polymer powders has been studied as an innovative technology and alternative to the traditional coating with an aqueous polymer dispersion or organic polymer solution. Dry particle coating consists of coating large particles (core material or host) with fine powder (guest). The adhesion of these guest particles is made using a mechano-chemical treatment or using a plasticizer. The plasticizer method is particularly when coating host particles that are relatively soft and very sensitive to heat and can be deformed by severe mechanical forces [5,6,7]. Compared to solvent and water based coating the dry coating method is favourable regarding environmental friendliness, safety and cost. The present contribution wishes to provide preliminary results to apply dry coating in the food and pharmaceutical field. More generally, the aim of this study is to obtain host particles coated with polysaccharides by dry coating process in a pan coating reactor. Proceedings - RELPOWFLO IV - 10th-12th June 2008 682.