PET Food Processing - March 2020 - 57

EQUIPMENT

KEY TO
KIBBLE
CONTROL
Preconditioners play a crucial role in delivering
consistent, safe and quality extruded pet foods.
By Jennifer Semple | jsemple@sosland.com

Today's trending pet food formulations featuring high
meat content and a broad range of ingredients are a
challenge to extrude. Preconditioners are a vital tool
delivering product consistency to the extrusion process.
"The preconditioner provides the environment to uniformly hydrate, heat and mix the food ingredients before beginning the cooking process," says Daniel Tramp,
technical sales, companion animal division, Wenger
Manufacturing, Inc., Sabetha, Kansas.
Preconditioning is a preliminary treatment of raw
materials before extrusion cooking to ensure a homogeneous pre-cooked mix on a continuous basis. "The
preconditioner hydrates, pre-heats and thoroughly mixes the raw material with injected fluids such as steam,
water, oil or slurries," explains Emmanuel Lavocat, food
& feed extrusion process engineer, Clextral, Tampa,
Florida. As formulations evolved, preconditioners were
developed "to respond to process requirements, improve
product quality and increase the capacity of the extrusion systems," he adds.

Delivering results
In high-volume processing, control of the process is
important. As more fresh, high-moisture-content ingredients are added to pet food formulations, it becomes
more challenging to uniformly mix the large volumes of
wet ingredients with the dry before transferring to the
extruder. Preconditioners help extruders have better
control of the finished product.

"By starting the cooking process in the preconditioner
by 'warming' the recipe before it enters the extrusion
barrel, the operator is able to reduce the amount of energy that needs to be transferred into the product while
in the extruder barrel," Tramp says. "This, in turn, allows
for improved control of the cooking step and the opportunity for increasing the consistency of the final product
attributes." Tramp points out that product flexibility is
also increased. "For example, the more homogenized the
mix is then the possibility for smaller particle size can be
present, which in turn can create unique final product
attributes that may be otherwise unattainable," he says.
Better process control can have a large impact on
overall process efficiency, but preconditioners can help
with the little things as well. "Rework is often driven by
fines creation, which is often most prevalent in non-homogenized product," says Adrian Martinez-Kawas, international project manager, Corporate Project Services,
a division of Wenger. "The homogenization that the preconditioner offers can have a positive direct effect on the
final product stability and structure."
Martinez-Kawas goes on to explain that the coefficient
of variation (CV) is a statistical number used to measure
how well a recipe has been mixed together. The lower
the CV, the more homogenized the mix. He says modern
preconditioners have taken steps to reduce the CV of a
mix. Specifically, the ability to have two mixing shafts
with independent speed, circumference and direction of
rotation has shown to improve the CV of a mix while

A preconditioner
continuously mixes
powder and liquid
ingredients and
replaces mechanical
energy with thermal
energy, which can
lead to lower overall
operating costs.
Bühler Group

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PET Food Processing - March 2020

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