The Role of Preconditioning in Food and Feed Extrusion

Published on: 03/25/2021
Author/s : Michael Joseph / Assistant Professor and Extension Specialist, Poultry Science, NC State University.

What Is Preconditioning? Preconditioning means to condition or prepare a material before it is processed further. In the context of extrusion processes, preconditioning occurs just prior to extrusion inside a piece of equipment called a preconditioner. The preconditioned raw material exits the preconditioner and moves into the extruder for further processing down the line. The dry raw ma...

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Dave Albin, Ph.D. Dave Albin, Ph.D.
VP, Nutrition & Extrusion Technologies
March 25, 2021

Good information. As always, the effects of preconditioning cannot really be divorced entirely from extrusion, which finishes the cooking process. And, ultimately, how all of this affects the end material is what matters.

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March 28, 2021
Fantastic overview.
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March 29, 2021
Dana Nelson Thanks Dana!
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April 8, 2021

Thanks, professor Michael Joseph, for keeping us awake on the preconditioning and extrusion principles...Is a very good overview useful to teach to our operators and apprentices...

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April 15, 2021
Michael:
Great overview. Very useful information. Excellent fact-sheet. Thanks!
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April 15, 2021
Important discusion about the preconditioner design results in a very important conclusions for the operation.
As preconditioner is an special " mixer" it will be important to know opinions on what is the most important in the design.
Parameters like, level of operation, time of retention range, one or two axes, sens of rotation of two axes, how to inyect the water and the steam, position of beaters at the inlet, in the middle and in the outlet, rotation speed, etc.
Because of mixing water, flours and steam is a complicated operation, is very important to built an homogeneous mix and to get that, it needs to pay atention to some details, as for example; how to avoid the wet flour to stick on the walls of preconditioner and after that to hook off and to cause problems at the extruder....( is an example in a tipical instalation of petfoods production)
Once we know about the principles and objectives of preconditioning I feel that the following discussion is about the preconditioner designs and operation of this machine.
Id like to hear your opinions.
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April 15, 2021

Thanks for your comments, Ignacio. You raise some important points. While there are several designs of preconditioners available, the predominant idea with those designs is to have maximum contact of the dry raw materials with that of water and steam to quickly create a precooked material.

As far as wetting of the flour to the walls of preconditioner is concerned, it's probably due to the difference in surface energy between water and the preconditioner walls (metal). Water has low surface energy than metal. As such water (water with raw materials) sticks to the metal and not vice-versa.

I think to reduce the sticking, probably the metal surface must be coated with a material that has less surface energy than water. That's my understanding about this issue.

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Kurt A. Rosentrater
Kurt A. Rosentrater
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  Ames, Iowa, United States
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Kurt A. Rosentrater Kurt A. Rosentrater
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Dave Albin, Ph.D. Dave Albin, Ph.D.
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