Applications of Fluidization in Food Industry

Fluidization is one of the technologies commonly used in the agro-food industry. It basically covers drying, cooling, agglomeration, granulation, and coating of food products. Fluidization is common because it is ideal for the processes of a wide range of both heat sensitive and non-heat sensitive products.

By fluidization, particulate materials are able take the properties of fluid. Gas (usually air) is made to pass through a product layer under controlled conditions to create uniform processing conditions. The gas performs two functions. It supports the weights of the particles and enabling them to flow with the gas. It is also it serves to cool, heat or dry the particles at direct contact with the solids material.

Fluid Bed Drying

Even though in recent years frozen foods increased its popularity, drying is still an important operation in the food industry especially in the preservation of food products. And fluid bed drying has significant advantages over traditional frying techniques.  It lessens the risk of food particles being overheated as well as giving easy material transport, high rates of heat exchange at high thermal efficiency. 

Fluid bed drying is for powders, granules, agglomerates, and pellets with an average particle size normally between 50 and 5,000 microns. For very fine powders or highly elongated particles, vibration for successful fluid bed drying is required.

Fluid Bed Cooling

It is somehow similar to drying but in fluid bed cooling, cold gas (usually ambient or conditioned air) is used instead. It is desired to remove heat from the particles but it additionally requires conditioning of gas to prevent the loss of volatiles or moisture. Cold surfaces can also be used to help remove heat further. 

Fluid Bed Granulation

Granulation transforms suspensions or solutions into dry, free flowing, dustless granules using granulators. Particles in suspension or solution are sprayed onto warm air, simultaneously drying and agglomerating the product.

Fluid Bed Pelletization

Pellets can be formed in 2 ways: liquid-layering and powder layering. Liquid-layering uses top spray coater to layer the active particle onto an inert core then forming the shape of a pellet. The spraying is done simultaneously with drying. Powder layering is done when the active particle is in the form of powder. Pelletization is achieved using a sprayer and liquid binder solution to hold the particles together. After that, the pellets are then dried.

Fluid Bed Coating

Food coating more commonly known as encapsulation, has a lot of functions including increasing shelf-life, masking taste or odor, improving visual appeal and improving ease of handling. Layering can be designed to lessen the release of constituents from the food particles. This is usually used for finer particles. Coating is done using an atomizer. Then particles are dried with air blowing upward through the column. 

References:

GEA Pharma Systems. Fluid bed processes - drying, cooling, agglomeration, granulation, pelletizing and coating of particulate materials. Sept. 22, 2012. http://www.gea-ps.com/npsportal/cmsdoc.nsf/webdoc/ndkw73fb8j

Smith, Peter. Applications of Fluidization in Food Industry. Victoria: Blackwell Publishing Asia Pty Ltd. 2007