Microencapsulation is applying a coating to small particles to isolate the substrate. People might microencapsulate in order to mask a bitter or bad taste. Ingredients could be encapsulated in order to provide a barrier from other ingredients for example, to improve stability. Ingredients might be encapsulated to provide a specific temperature release (as in a baking application), or a pH release, or a sustained or modified release. All of these reasons for encapsulation could be accomplished at Watson Inc. using their expertise in fluid bed microencapsulation.
In the first part of this blog, we will be discussing the use of what we call “hot melt microencapsulation”. This is utilizing fluid bed technology to apply a molten coating to a substrate. One of the important parameters is the selection of the coating material. What temperature do you want it to melt at? What is the application? Are there any GMO or other requirements on it? All of these things need to be considered when selecting the coating material. Other important product variables that need to be considered are the particle size and morphology of the substrate. The surface area of the substrate along with the shape of the particle will ultimately determine how much material needs to be applied in order to fully encapsulate the substrate. Finer particles will have much more surface area than a larger particle, and thus will require more coating to encapsulate. Similarly, compare a smooth surface ping pong ball, with the surface of the moon. While the ping pong can be easily coated because of its smooth surface, the surface of the moon is full of craters, and would require material to fill in those craters before applying a smooth uniform coating.
Fluid Bed Microencapsulation
In the fluid bed microencapsulation process, you are taking a molten solid, and spraying it using atomizing air to break it into droplets, hit the substrate, and spread on the surface of the substrate. The droplets are applied layer by layer until they coalesce into one integral film. Process variables include the temperature of the molten coating material, any heat loss on its way to being applied, that amount and temperature of the atomizing air using to break the coating liquid up into small particles, the product temperature of the substrate being coated, and the total amount of coating applied.
The use of the “hot melt microencapsulation” is performed daily at Watson where we take this art form and make it a reproducible, controllable, testable, science.
We have alot of other information available on the Microencapsulation page of our website.