PET Food Processing - June 2018 - 56


the first part of the oven helps prevent this. Another option is to introduce steam in the beginning, which will
enable the product to bake out the moisture in the center
of the large biscuits."
Extruded products most commonly require a dryer. "When a product is made on an extruder there is
usually moisture added during this cooking step in
the form of steam or water to get the correct product appearance and cook level," explains Galen Rokey,
process technology director, Wenger Manufacturing,
Sabetha, Kansas. "This moisture must then be removed for product shelf life. Typical extruded pet
foods may contain 20% to 30% moisture prior to
drying. Conveyor speeds within the dryer allow the
proper bed depth and retention time. Drying temperatures are another operating parameter needed to
reach a product moisture level between 6% and 8% as
the product leaves the dryer."
Extruded products for human consumption are typically dried below a moisture content of 5% for bite texture, flavor and structure stability. Pet food extrudates

are more dense than human food and are normally
dried to a final moisture content of 6% to 9% for shelf
stability and food safety.

Critical controls
Oven and dryer manufacturers build in automation and
controls designed to optimize the operating parameters.
RBS ovens utilize independently controlled blowers for
top and bottom airflow. An RBS 3-pass dryer can increase throughput in a smaller footprint by continuously
blowing warm air on top of the product as it drops from
one tier of the dryer to the next. All sides of the product are exposed to the warm airflow as it gently flips and
tumbles to the next level.
"Benchmarking an oven is important," Pallottini
says. "A benchmark defines the bake profile for each
product formulation by measuring the four key
variables in an oven: temperature, airflow, humidity and heat flux." The RBS Scorpion Data Logging
Measurement System is a hardware and software measurement system, with a 32-input channel, data logger

APEC has been engineering custom process solutions to solve the challenges of pet food manufacturers
since 1992. We understand that you work in an ever-changing industry. That's why we have continued to
innovate our process and control systems to improve your performance, quality and bottom line. Whether it's
from our extensive equipment line or a custom solution, you can rely on APEC for exceptional:

Dry and Liquid Coating | Weighing | Mixing | Batching | Blending


+1 (616) 374-1000 *


Table of Contents for the Digital Edition of PET Food Processing - June 2018