Drying and cooling are critical stages in pet food manufacturing. Drying removes excess moisture, while cooling stabilizes the temperature, making the product ready for packaging and sale. Both are essential steps in producing safe, high-quality pet food.
Drying technologies typically include methods like convection drying, vacuum drying or freeze drying, which apply controlled heat and airflow to remove moisture while maintaining nutritional integrity.
Cooling technology usually involves forced air, chilled air or cooling tunnels that rapidly lower the temperature of the food while ensuring the final product remains structurally intact.
When it comes to the latest innovations, Lloyd Parks, VP Sales Americas at Cuddon Freeze Dry, said there is a range of options for producers to consider.
“Freeze drying has continued to gain popularity because of its shelf life benefits along with nutritional preservation,” said Parks. “Vacuum drying has also been getting some attention as it is a midpoint between fully cooked and freeze drying.”
Extrusion and baking have also made progress in limiting high temperatures for extended periods of time, said Parks. “Wind velocity and lower-temp cooling towers are now being used in some products looking for lower temps and minimal processing,” he noted.
By integrating the latest drying and cooling technologies, pet food producers can ensure high-quality, nutritious and safe products while improving operational efficiency and reducing environmental impact.
Ensuring a consistent drying process
Regardless of technology, proper drying comes down to the time and temperature a product is exposed to during its process. This is followed by sample testing moisture at the end of the process. Each process moisture result will dictate if any settings need to be adjusted to reach the desired moisture. This holds true for extrusion, baking, freeze drying or vacuum drying.
“Proper drying relies on having accurate, real-time data about product characteristics from the extruder,” said Robert Sunderland, director of Dryer Technology with Wenger. “With an advanced control system, dryer operation uses this data to optimize important aspects such as drying time, temperature and airflow.”
One key to a food-safe process is to maintain consistent drying throughout production runs, said Sunderland.
“Product that is not dried correctly retains too much moisture and can be re-contaminated after it leaves the dryer,” he noted. “A proper dryer design will enable even product spreading and consistent bed depths so that heated air can access every individual item correctly for a precise amount of time.”
Will Henry, director of R&D and product development at Extru-Tech, agreed, adding, “The mechanical design of our drying/cooling equipment ensures that the pet food, individually and wholly, is dried/cooled in a manner that is consistent and repeatable. Any variability will render inconsistent product moisture.”
An additional step is to install an inline moisture measurement analyzer to ensure product from the dryer is at the target moisture level. This allows corrections to be made immediately to minimize waste.
“Using and applying the correct instrumentation to record water activity and/or moisture is the first step,” said Henry. “Assigning the correct control point and establishing an effective corrective action procedure is second. Understanding that criterion should be tailored to a given product is last, and certainly the most important.”
Dave Carney, area sales manager, Petfood & Aquafeed, Buhler Group, said using sensors to accurately measure moisture helps prevent spoilage in the bag. Buhler’s DryingPro uses a microwave technology control system that adjusts the dryer’s production parameters to keep moisture content steady.
“The result is a reduction in the fluctuation in moisture content currently seen at the end of the dryer,” said Carney. “Where today there are high safety margins in place to ensure no product leaves the factory with higher moisture contents than allowed, those safety margins can be reduced due to the accuracy of the system, resulting in less overdried product and therefore more product to sell.”
Efficient drying to reduce energy use
Traditional dryers require significant energy to operate, so pet food producers are always looking for ways to reduce energy usage without impacting drying performance. Fortunately, there are several options available to increase energy efficiency of existing dryers, said Sunderland.
“An upgraded dryer control system is critical,” Sunderland said. “Installing a heat exchanger system on the dryer outlet can result in up to 20% energy savings by recuperating exhaust air. Also, burners can be retrofit to accommodate alternative, lower cost fuels.”
To achieve even higher savings, installing a high-temp heat pump system with larger coils can help a company reach its sustainability goals. “A dryer upgrade is not only important for sustainability, but it can also generate tremendous monetary savings, within short payback times,” said Sunderland.
The consumer’s perception of how a product is manufactured and its carbon footprint is a leading influence to become more sustainable. A more efficient drying system requires less power to operate and therefore less cost, which is always of interest to a pet food processor.
“Drying efficiency is a high priority, so a lot of new technology is now available for pet food manufacturers,” said Jay Pokorny, Innovation Group leader with Extru-Tech. “Developments in controls automation and energy recovery systems can reduce the total energy needed in the manufacturing process.”
Renewable sources of energy can lower costs and improve sustainability.
“Many of our customers are investigating steam technology or electric heat alternatives as opposed to using gas heat sources,” said Carney. “Using either of these methods will drive their carbon footprint to essentially zero. We also offer energy recovery methods for additional savings by reconditioning once used heated air.”
Cooling technologies help maintain nutritional value
Using technology, pet food processors can cool product to optimal levels without compromising safety, quality or integrity of the product. Advancements in cooling technology are helping to maintain nutritional value by improving precision and reducing thermal damage.
There are several cooling methods designed to maintain nutritional ingredients by protecting sensitive ingredients from excessive heat exposure and oxidation, which can degrade essential nutrients and reduce product quality.
1. Cryogenic cooling uses ultra-low temperatures achieved with liquid nitrogen or carbon dioxide to rapidly cool pet food without affecting moisture content. Quick cooling reduces nutrient degradation by limiting exposure to heat and oxygen, preserving vitamins, minerals and amino acids.
2. Air impingement cooling cools food quickly by directing high-velocity, low-temperature air streams directly onto the product. This rapid cooling method minimizes bacterial growth and helps retain nutrients, particularly in heat-sensitive formulations.
3. Vacuum cooling works by removing pressure around the product and facilitating rapid cooling through water evaporation. This method is gentle on pet food and helps retain nutrients by minimizing thermal stress.
4. Hybrid cooling systems combine different cooling methods, such as air and cryogenic, to achieve a balance between energy efficiency and nutrient preservation, which is particularly useful for fresh or minimally processed pet foods.
Today’s cooling systems now use sensors and IoT technology to monitor and adjust cooling temperatures precisely throughout the process. By keeping tight control over the temperature, these systems help avoid nutrient loss from overheating while ensuring that all parts of the batch are cooled evenly.
“Applying sensors and automation to the cooler and product help to steady-out the cooling process, thus reducing quality variation of the finished product,” said Pokorny. “Once tight control of product variation is achieved, then things like moisture and water activity can be optimized.”