Commercial food manufacturing equipment is no small investment. When shelling out the dough for a new state-of-the-art machine, pet food processors expect the equipment to last. Equipment must weather product changes, throughput increases and the everyday wear and tear commercial pet food processing puts on a machine. 

Pet food and treats are changing in raw materials and forms. “Pet food processors don’t want any of the cereals,” says Mian Riaz, Ph.D., department head, extrusion technology program, Texas A&M University, College Station, Texas. “They want all proteins and new grains like quinoa. We’re seeing all kinds of new ingredients and carb-free, gluten-free and grain-free.”

These new ingredients, free-from and high-protein products all require different equipment components and settings and have an impact on the equipment. It’s important that the extrusion system can deliver the desired finished product to ensure optimized production and maximum equipment life. To adapt to these changing product needs equipment must be flexible to handle changeovers quickly and efficiently. 

Finally, keeping equipment clean and well maintained helps it run smoothly with minimal interruptions. Clean equipment produces pet food and treats that meet a processor’s high standards more consistently and efficiently. And pet food processors can extend the life of their extruders by implementing a maintenance program. 

Choose the appropriate equipment
The key to equipment that will last is choosing the right equipment in the first place. “Depending upon the type of extruder, different functions can be performed,” says Galen Rokey, process technology director, Wenger Manufacturing, Sabetha, Kansas. “These include expansion, gelatinization, homogenization, dehydration, mixing, pasteurization, protein denaturation, shearing, texture alteration and product shaping.” Before purchasing an extruder, pet food processors should know the finished product and volume they require; the shapes, sizes, desired textures and the raw materials they’ll be working with from the outset.

“Processors need to let equipment manufacturers know what kind of finished product they want so the manufacturers can design the extruder for their application,” Riaz says. “There is low shear, medium shear and high shear, all designed for different products, and similarly, the twin-screw handles different products.”

Pet food processors must establish operational requirements up front with their equipment suppliers about their goals so the extruder can get the job done in an optimal way. These conversations, as well as testing the raw materials on suppliers’ equipment, will help pet food processors get a clear picture of what extrusion system and components will work best for their products. “This will determine overall screw length, screw elements for best mixing and cooking, and functionality of control systems to proportion ingredients and liquids while fine tuning speed and temperature,” says Dave Carney, area sales manager, Buhler, Cary, North Carolina.

Whether or not the product will be raw or cooked is also an important distinction processors need to make to extruder suppliers, as extruders can do both. “I need to understand if a customer wants to portion the extruded product as a raw product or if they want to portion the cooked product,” says Jay Wenther, Ph.D., director of meat technology, Handtmann Inc., Lake Forest, Illinois. “This assists in determining what extrusion may work for them and be the most economical for their business.”

While most pet food is made in single-screw extruders, that may not be the best hardware to process high protein treats and food that is growing in popularity. “Some products can’t be made on a single because a twin-screw extruder can handle very viscous, oily, sticky materials,” Riaz says. “We use a twin screw when you need high protein, high fat or high moisture.”  

As the protein level in a recipe is increased – usually at the expense of starch – there are changes in product expansion, texture and durability. Rokey explains, “Higher protein levels usually result in less expansion as many proteins are less viscoelastic than starch. Increased levels of protein usually result in firmer or harder textures compared to starchy recipes. Many proteins are not functional, in other words they will not contribute to expansion and binding in the extruded product matrix. Generally, products made using recipes with higher protein levels will have less durability and may break and generate fine dust during handling and transportation.”

Clextral gives pet food processors the ability to test their products on Clextral extruders at one of two research centers, one in the US and another in France. At these centers, Clextral’s customers can develop and test new formulations and take advantage of the company’s mechanical, electrical and automation training services. First and foremost, though, pet food processors can have the opportunity to test all the different components Clextral offers on its extruders to find the appropriate hardware for their products. “Clextral provides many options including specific die designs for innovative shapes and special knives that are able to cut highly viscoelastic products in a very consistent process,” says Alain Brisset, Clextral SAS, Firminy, France.

Beyond the actual machine, it’s important that the production line matches the throughput a pet food processor expects. Over-sizing the line is not always the best strategy for expansion and can potentially hinder the line from running at its best. “Instead of buying a larger capacity and only running it half the time, buy a line for five tons and run five tons,” Riaz says. “If you grow, buy another line. To process properly, you have to have the right capacity on the entire system both upstream and downstream from the extruder.”

Clextral extruded dog treatsAdapting to diversity
Over the years, it stands to reason that a pet food processor may need to expand its product offerings to keep up with trends. That could be adding new flavors or shapes to an existing product or maybe introducing high protein or gluten-free products to seize some trendy sales dollars.

“Pet food processors need to ultimately take a close look at what they are currently producing and what products they have in the research and development pipeline,” Wenther says. Accommodating these product expansions is easier with equipment that is flexible enough to adapt to a growing business. An extruder that lasts is an extruder that keeps up with a changing business.

“If the system was built for one product and one product only, then likely the wrong machine was selected,” says John McIsaac, vice president, strategic business development, Reiser Inc., Canton, Massachusetts, illustrating just how important flexible equipment is to a successful operation. “Your consumers’ – or more importantly, their owners – constantly want new products, and you want to be able to meet that demand,” he adds.

Flexible equipment is designed for quick changeovers. While one extruder may be capable of producing many different products, many of the components on the extruder may need changing to accommodate the next product’s needs. “It may take several extrusion forming dies or a different extrusion configuration,” Wenther says. Screws, dies and knives must all accommodate new raw materials and create a new shape, size and texture.

“For example,” Wenther explains, “a processor may want to extrude 17-mm sticks through a 24-lane extrusion system on one day and then make a thicker strip product the following day. With the ability to change the adapter insert, the forming die and block off lanes of the 24-extrusion system to use 12 lanes, they can easily produce a completely different product with the same extrusion technology.”

The screw, which mixes and sometimes cooks the dough, lives inside the extruder barrel. The screw configuration, however, needs to change to handle a new formulation and create a different texture. Operators require easy access to the screw to remove it and change its configuration. To do that, Clextral’s twin screw extruders have an automatic hydraulic barrel opening to provide screw access at the push of a button. “In addition, easy access to the screw-caps and screw pattern enables quick reconfiguration during changeover, and offers convenient, preventive maintenance,” Brisset says.

Dies and knives, which control the size and shape of individual pieces, also need to be quickly and easily changed with each product. “Dies have a quick-clamp design for easy removal and replacement, and cutters offer complete adjustability,” Brisset says of Clextral’s extruders.

Another aspect in the extruder that needs to be flexible is the pumping system. A pumping system needs to be able to deliver accurate portions and handle a diverse array of viscosities. “A piece of equipment designed to be versatile, like a Vemag extruder, will have the ability to swap pumping elements or front-end attachments to allow for new products,” Reiser’s McIsaac says.

The Vemag extruder, offered by Reiser, features a powerful positive displacement double-screw pump that provides high portioning accuracy while transporting product gently without degradation. There are a number of double-screw configurations offered which allows pet food processors to produce a variety of products with one machine. “A Vemag using a double-screw to produce a high volume of dense product can also be used to produce a highly accurate stream of liquid product with a simple change of the double-screw pumping element,” McIsaac explains.

Maintained for the long haul
A thorough and routine sanitation and maintenance program can keep an extruder running efficiently for many years. Conveniently, many of the same characteristics that make extruders flexible also make them easy to clean and maintain.

“A lot of the new equipment design improvements focus on food safety,” Riaz says. “Today, responsibility rests on the manufacturers to provide equipment that meets sanitary standards. New designs are easier to clean, use CIP, open designs and no hidden spots where microbes can grow and contaminate the product.”

These design elements make clean-up and changeovers go more quickly, saving time and boosting efficiency. Clextral designed its extruders for hygienic processing including open profiles for full machine access and continuous hygienically welded machine construction, eliminating bolted joints. The company’s Evolum+ line of equipment is constructed with full stainless steel or stainless/painted steel construction. It also features open design for easy access. In Clextral’s Preconditioner+, the additional conveying bottom screw allows operators to completely empty the tank quickly, which is useful in speedy cleaning and changeovers.

A thorough sanitation program and hygienically designed equipment keeps equipment free from bacteria and build-up that can slow production down. A proper maintenance schedule and equipment that provides easy access for quick maintenance can help prevent breakdowns and speed up repairs when they do happen. “Keeping the screws and barrels properly maintained for best product results and maintaining consistent ingredients will support an efficient extrusion process,” Carney says.

Easy access for changeovers and sanitation also comes in handy during maintenance. Open design lets technicians get to components for repair quicker with less fuss. McIsaac says processors should consider the support an equipment supplier can offer after the equipment is purchased, installed and operational. “Select equipment from companies that have their own factory-trained service technicians,” McIsaac recommends. “Better yet is if these technicians are local for faster response and reduced downtime.”

Understanding a current product line as well as the pet food products of the future will help processors ensure they get the right extrusion system that will go the distance. Purchasing a flexible system that is optimized for their product line will help equipment operate at its best at all times. And staying on schedule with a sanitation and maintenance program will keep everything moving smoothly and get the most life out of an extruder. 

Read more about pet food processing equipment on our Equipment page.