You are here

Extrusion test methods

Animation of back extrusion method

Extrusion testing has many applications within the food, and other industries, for texture assessment. This method is relevant to semi-solids or viscous liquids, where the rheological properties of the product affect the flow.

Extrusion can be divided into two categories; forward extrusion and back extrusion. Forward extrusion is when the test sample is placed into a confined container and then forced through an orifice or grid. The foods resistance to this extrusion is then measured. The size of the orifice or grid selected is dependent upon the product being measured and the textural property of interest.

Back extrusion is typically performed with the product being measured is placed in an open top cylinder, and a piston with a diameter smaller than the cylinder, is forced down into the sample. The result is that the product flows back between the space created by the piston and the cylinder.

See FTC's extrusion test method capabilities.

Test procedures

For example, sour cream, when not processed properly, can be grainy. By forcing sour cream through a small orifice – using forward extrusion- one will either see a smooth force level or a jagged one. The jagged one happens when the grains alternately become plugged and unplugged in the orifice building then releasing back pressure.

Back extrusion is a more common method of extrusion testing. The key factor to consider in back extrusion is the gap between the piston and the cylinder. This is called the “annulus” and the smaller the annulus, the greater the resistance to the flow.

For consistency in testing of viscous liquids, once decanted, samples should be left to recover structure in a controlled environment.

Extrusion testing fixtures

Extrusion test methodsExtrusion test results comparing firmness of yogurtsExtrusion applications in food industries

Trusted by customers across the world

As a Meat Scientist and program leader for the University of Nevada, Reno, I need to ensure that equipment I use in my lab is reliable, durable, versatile, and accurate. For texture analysis of meats, there are many systems available in the market. Over the last 15 years of my career, I¹ve worked with many of them and had great and bad experiences with different brands.

Last year, I decided to try a different system for my lab, the TMS-Pro Texture Analyzer from Food Technology Corporation. The system has all the attributes I was expecting to conduct texture and shear force analysis in a quick and not complicated way. The customer support provided by them is outstanding and their technicians are always ready to walk me through new procedures and initial set up. If you are looking for a reliable system for food texture analysis and special customer service, the TMS-Pro is the system to go for and the Food Technology Corporation is the one that can deliver the support.

Amilton de Mello
Assistant Professor of Agriculture, Meat Science and Food Safety
https://www.unr.edu/anvs

Excellent customer service. Consistently followed up and offered help without asking. Relatively low priced - provides good value. 

Easy to switch different load cells. Used it for 5 lab sessions for 68 students this semester and performed well.

 

 

Professor Jeyam Subbiah, University of Nebraska
https://nebraska.edu/

Nestle purchased a texture system from Food Technology Corporation in 2006. Since then I have recommended the texture system to several vendors in North and Central America. Staff at FTC was able to develop a simple training manual and procedure for the texture system allowing easy training in short period of time.

From purchasing of equipment through to installation and start-up, the level of personal care and service was remarkable. Shirl Lakeway and his staff at Food Technology Corporation are patient and understanding, and are always at our disposal for any assistance. Since we bought the equipment we have had no problems and feel very secure knowing that we can count on FTC for their support and service.

Dr Mawele Shamaila, Nestle - USA
http://www.nestleusa.com/