Morphology and strength of cellulose derivatives coatings in fluid bed processing

Abstract

Microencapsulation is defined as a process in which small particles or droplets are surrounded by a coating in order to obtain small capsules with many valuable properties. One of the most commonly used and most promising techniques to realise microencapsulation in the food industry is fluidized bed coating. The effectiveness of the fluidized bed coating process can be verified by the quantification of the coating quality. Verification of coating quality is an important issue for companies that produce encapsulated food ingredients since deviations from the intended value of coating thickness may cause problems related to release of core material. The main goal of this PhD study was to examine the quality of coatings obtained from four selected water-soluble cellulose derivatives: methylcellulose, low and high viscous type of carboxymethylcellulose and hydroxypropylcellulose. The quality of the coatings was examined for two aspects: coating morphology and coating strength. To this end, the Confocal Laser Scanning Microscopy (CLSM) was used to determine the coating morphology and the repeated impact tests (RIT) were applied to evaluate the attrition strength of cellulose derivative coatings on various core materials. Within this PhD research, coating quality and coating thickness of selected materials were quantified. Furthermore, the relationship between coating material properties and the coating quality was examined