Encapsulation of Orange oil using fluidized bed granulation

Abstract

The objective of this research was to determine if orange oil can be spray dried and agglomerated in a single step process called granulation and if so, to compare the products prepared using granulation to the traditional processes of spray drying and then agglomerating. The processes that were studied as a part of this research were spray drying (SD - A conventional process widely used in industry), agglomeration of spray dried Flavors (SDA) and fluidized bed granulation (FBG). The model system used to evaluate the two different processes was an orange oil emulsion. They were made by first preparing a slurry 55% in solids (carrier in water). The carrier was a blend of Maltodextrin (MD-150 as bulking agent) and Modified Starch (Capsul™, an Octenylsuccinate acid derivatized starch as emulsifier). Orange oil was added at 25% of the carrier solids level and emulsion was made using a high shear rotor-stator blender. The said emulsion was subjected to spray drying and the resultant spray dried emulsion was agglomerated. The emulsion with same composition was also used for fluidized bed granulation (FBG). The resultant product, orange oil encapsulates were analyzed for Limonene Oxide content under storage (Shelf life study), Particle Size, Density, Orange Oil retention and Moisture Content. It was observed that FBG samples had higher density than SD and SDA samples. Density was found to be proportional to run time of the process and SDA samples had higher density than SD samples. Under the study operating conditions, fluidized bed granulation produced larger particles compared to spray drying or SDA. As one would expect particle size was found to be proportional to run time of the process (FBG and SDA). In case of FBG, it can be explained by the continuous spraying of emulsion while processing, which results continuous drying and film formation on granules (particle growth). Under the study operating conditions, FBG products also had a lower moisture content compared to other products. FBG samples had the highest oil retention followed by spray drying and SDA; The SDA batch with shortest run time (about 30 mins) had the least oil retention. While conducting the shelf life study, it was observed that granulation samples had the lowest limonene oxide content, hence less oxidation after four weeks of storage followed by agglomerated samples. Spray dried samples were observed to have highest limonene oxide content and hence, the highest oxidation after four weeks of storage as smaller particle size contributes to a higher available surface area per unit volume for oxidation. Overall, it was observed during this study that fluidized bed granulation produced orange oil encapsulates that possessed better properties such as more resistance to oxidation, better retention of flavors and higher density than spray dried orange oil.