Sanitary Homogenizers- What do they do? What Different Types are There?

May 1, 2014

One of the most commonly encountered, yet intimidating pieces of equipment in a food or pharmaceutical plant is a homogenizer. Be it a mixer, a colloid mill, a shear pump, or a high pressure Gaulin homogenizer- mixing, blending, and breaking down of products to create stable emulsions is one of the most ubiquitous processes across industry. This post will take a look at sanitary homogenizers, what they are, how they are classified, and what technologies are available.
To begin, what is a homogenizer? Homogenization is any of process used to make a mixture from two mutually non-soluble liquids into a stable emulsion. An emulsion is a type of colloid in which a substance is microscopically dispersed throughout another substance. When each of these two substances are continuous and liquid, this is known as an emulsion. In an emulsion, a third component, known as a surfactant (emulsifying agent or stabilizer) must be present in amounts adequate to prevent coalescence of the dispersed phase.

The equipment that makes the homogenous mix is known as a homogenizer. Generally speaking, the purpose of homogenizer is to take a large amount of mechanical energy and impart it into the two fluids to create an emulsion or dispersion. Homogenizers accomplish a variety of specific goals including improving product texture and flavor, particle size reduction, and cell disruption. Tank mixers, inline mixers, high shear mixers, shear pumps, colloid mills, and high pressure homogenizers are al, by definition, homogenizers.

APV Homogenizer

APV Homogenizer

The difference between sanitary mixers, shear pumps, colloid mills, and high pressure homogenizers is the amount of energy imparted on the fluid as reflected by emulsion particle size. Generally speaking, the smaller particle size required, the larger the amount of energy we need to put into the fluid. For reference, a mixer at 1500 RPM can create emulsions with particle sizes that vary between 10-20 micron, while a high shear mixer at 6000 RPM can create an emulsion with particle sizes as small as 2-5 micron.

The highest energy homogenizer that we use to achieve stable emulsions with the lowest possible product size is the high pressure homogenizer. First demonstrated at the 1900 World’s Fair by Auguste Gaulin, high pressure homogenizers were first used to treat milk. Because of this designation, the term “homogenizer” has historically related to the high pressure process developed by Gaulin.

A high pressure type homogenizer basically consists of a positive displacement pump attached to a homogenizing valve assembly. The pump forces fluids through the homogenizing valve (a small, fixed orifice) at a high pressure. The theory of how homogenization is actually accomplished in a high pressure homogenizer has long been disputed, but it now appears that turbulence created as the fluids pass through the homogenizing valve is the primary mechanism. Future posts will elaborate on homogenization theories and equipment considerations.

To conclude, homogenization is any process used to make a continuous mixture from two immiscible fluids. The equipment that does this is a homogenizer. Holland has a wide variety homogenizers we specify, including mixers, colloid mills, shear pumps, and high pressure homogenizers. While this post touches on high pressure units, future posts will get into additional detail. If you have any questions about homogenization in your specific application, contact a Holland sales engineer today!