Fluidized bed processing in food (bio)technology

Dewettinck, K.; Huyghebaert, A. . Dept. of Food Technology and Nutrition

Fluidized bed processing in food (bio)technology

1999

Dewettinck, K. | Huyghebaert, A. (Gent Univ. (Belgium). Dept. of Food Technology and Nutrition)

Originally developed as a pharmaceutical technique, fluidized bed coating is now increasingly being applied in the food industry to tune the effect of functional ingredients and additives, and to supply the food (bio)technologist with a wide variety of encapsulated versions of powdery food ingredients and additives. Main benefits of such miniature packages, called microcapsules, include increased shelf life, taste masking, ease of handling, controlled release, improved aesthetics, taste and color. By means of a thermodynamic model Topsim the effects of major process and ambient variables on the thermodynamic operation point were quantified. The effects of process variables such as particle size, atomization pressure, and inlet air temperature on coating efficiency were evaluated by means of response surface methodology. The atomization pressure, often understood as only a droplet size influencing factor, was proven to have a more complex effect since it also influences the droplet velocity and fluid-bed temperature. It was demonstrated that undesirable side-effect agglomeration is primarily influenced by coating characteristics such as hygroscopicity, water binding capacity, and viscosity. These factors and the molecular weight of the biopolymer being applied also influence drastically the final coating quality. Moreover, it was established that side-effect agglomeration and coating formation must be related to glass transition phenomena but further experimental work is necessary to get a clearer understanding.

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