Comparing and Contrasting Liquid Coating Equipment Solutions

comparing liquid system pumps

There are a number of ways to apply liquid coatings to foods and pet food. Using the right liquid coating equipment solutions for your coating type and product can improve product quality, and reduce waste, maintenance expenses, and downtime. In this blog post, we’ll discuss different liquid coating equipment solutions. We’ve updated this blog post in 2021 to give you more information about the latest liquid coating equipment solutions.

Comparing and Contrasting Liquid Coating Equipment Solutions

Screw Conveyor

spray coating screw conveyorAs extruded products move through a screw conveyor, they can also be coated. This requires the use of spray nozzles over the screw conveyor. However, the spray nozzles actually coat a relatively small portion of the product. This means the coating relies on mixing action to properly and uniformly coat the product. Spray liquid coating equipment solutions using screw conveyors don’t provide much mixing action and comparatively little retention. Reducing the screw conveyor flights or using ribbons in place of solid flights can improve the mixing action. Paddles with a slight pitch between the ribbon flights will move the product in the opposite direction of the conveyor, which can also improve the mixing action.

Ideal Application Method

Using a screw conveyor and spray nozzles is a popular method for coating materials. This arrangement can be used for many different liquid coatings and materials, though there are certain circumstances that are ideal. Since the spray nozzles can become clogged when working with liquids that contain high levels of fat, oils, sugars, or salts, it’s ideal to test the viscosity of the liquid first. Since the mixing action is essential to the liquid coating, but it can also break apart pellets or particles that are especially fragile, this method also works best for tougher materials that are likely to retain their shape.

Rotating Drum

The rotating drum is a common liquid coating equipment solution in food and pet food production. With this method, the product tumbles through a tilted drum, across raised flights on the inside. This system provides the unique advantage of adjustable retention. The drum also eliminates pinch points, which can cause fragile products to break. However, this method also has some disadvantages. Similar to the screw conveyor, the rotating drum requires mixing action to work. By putting the spray nozzles into a plenum prior to entry into the drum, this process can be improved.

Ideal Application Method

The rotating drum method is another popular liquid coating method. Since the mixing action is gentler compared to the screw conveyor, and doesn’t have pinch points, this operation can work better for more fragile pellets and other particles. Since this method also offers control over retention time, it can also work better for liquids that require longer periods to soak into the material. Since this method also requires spray nozzles, it’s ideal to work with liquids that aren’t prone to clog and don’t use excessive fats, oils, sugars or salts.

Rotating Disk

spray coating rotating diskThe previous systems all use spray nozzles to coat the product. Systems using spray nozzles have a number of challenges. Spray nozzles can easily clog, especially when working with coatings with heavy fats, oils, sugars or salts. Liquid coating equipment solutions that bypass spray nozzles can avoid many problems resulting from clogs. Rotating disk applicators like the Mistcoater use spinning disks to apply liquid to the product. The liquid coating drops onto a disk spinning at a high RPM, which atomizes it into a fine mist and covers the product. This method not only provides uniform coating, but also requires less maintenance.

Ideal Application Method

The rotating disk liquid coating system provides versatility and efficiency. Since the rotating disk applicator doesn’t require mixing action to coat the material, this can be ideal for fragile pellets and particles. Since there are no nozzles to clog, this can also work well for liquids with a high oil, fat, sugar or salt content. For systems that are prone to clogging or crumbling fragile particles, a spinning disk system can be an ideal upgrade to reduce maintenance costs, reduce material loss, and improve finished product quality.

Batch Mixer

These liquid coating equipment solutions are usually located just before load-out or packaging. These mixers used paddles, or a combination of ribbons and paddles to move coatings over the material. This allows the product to move through the mixer quickly without getting damaged. A vacuum can also be drawn on this mixer, allowing it to draw the air out of the product and then draw liquid into the product when the vacuum is released. With this system, it’s also easier to add a light level of liquid to the product. The disadvantage is that this system requires more headroom, and it can be expensive.

Ideal Application Method

The batch mixer liquid coating method also offers versatility and efficiency. With the ability to choose between vacuum coating and mixing action to coat the materials, it’s easier to accommodate a wider array of materials and liquids with varying properties. Vacuum coating can help to increase liquid retention, as it allows the liquid coating to enter the pores of the pellets or granules. This method also makes it possible to add multiple liquid layers to the product. If the liquid coatings require separate applications to retain their properties or to fully absorb into the product, combining batch mixing with vacuum coating may work best.

Each of these methods has advantages and disadvantages. Finding the right liquid coating equipment solutions means finding a good fit for your product, coating, and the rest of your existing equipment. Work closely with your system engineer and provide as much information as possible about the coating and materials you’re working with. This will help you to optimize your system.

Solving Application Problems in Dry Pet Food Palatants

dry pet food palatants

In our previous post, we discussed some of the problems and solutions in applying liquid pet food palatants. Pet food palatants are also available in dry forms, which present different advantages, as well as different challenges. Solving problems in dry pet food palatant application requires a close look at the application equipment, as well as storage procedures, controls, weights, and more.

Dry Pet Food Palatants: Problems and Solutions

The first form of pet food palatants were dry additives known as “digests.” These digests were proteins that were broken down and applied to dry foods in order to mimic the taste and smell of meat that cats and dogs naturally crave. Today, pet food palatants are much more diverse, but dry palatants still play an important role in pet food processing.

Storage for Dry Palatants

As you might expect, dry palatants will not withstand moisture well. Dry palatants are made to adhere to products with the introduction of fats or oils, so too much moisture early on will cause them to stick together and spoil. Proper storage is essential, especially in humid environments. The dry palatants should be completely sealed until they are ready for application.

Flow Control

Though dry palatants will not cause clogs the way liquid palatants will, they do cause other problems. Dry materials are susceptible to a number of flow problems. The materials might stick together from moisture or static electricity, or they might stick to equipment surfaces. Agitation will keep the dry digest flowing properly, and stainless steel construction or non-stick coating will prevent sticking.


For the dry palatants to stick to the product properly, retention time is important. The dry palatants are usually applied after a layer of fat or oil, which allows the palatants to stick. If the fats or oils do not have time to absorb properly, the layer will be too thin to absorb the palatants. Or, if the layer is too thick, it will encapsulate the palatants. Thorough equipment testing is the best way to ensure that each stage in the process works properly.


Uniform application is also an important consideration. For the palatants to be uniformly applied, the fat or oil must also be uniformly applied. If you are finding a lot of dry palatant at the bottom of the pet food bag, the dry layer is not sticking properly. Changing the application point or the amount of liquid used on the surface can help to solve this problem.


Dry digest is typically applied at a lower rate than liquid palatants, usually between .5 and 2.5% percent. With this relatively low amount, a light, even layer over the product is especially important. A vibratory spreader or a rotary slinger can effectively and evenly spread the palatants over the surface of the product.


With the low amount of dry palatants used, an accurate and consistent control system is also important for measuring the flow of all ingredients. With more accurate instruments to measure the flow rate, the more accurate the application will be. In the case of dry palatant application on kibble, the flow of the kibble is considered the master flow, and the flow of the other ingredients are slaved to the master flow as a percentage.


Proper application of dry palatants requires consistency, uniformity and accuracy. Relatively small environmental changes can easily disrupt this process. Temperature, humidity, and flow rates should remain consistent. The equipment should also be monitored and verified to ensure it is working properly.

Dry palatants and wet palatants work together to make nutritious pet food appealing to dogs, cats, and other animals. When application processes behind these additives work properly, the system can work efficiently and the finished product is high-quality. The right system design can solve many of these problems from the start and keep operations running smoothly for years to come.

Solving Application Problems in Wet Pet Food Palatants

application methods in liquid palatants

Palatants give pet food the taste and aroma that cats and dogs naturally crave in their food. However, applying palatants presents a number of challenges to pet food processors. Pet food palatants can be dry or wet, and each has unique advantages and disadvantages. In this post, we’ll take a closer look at application problems and solutions in wet pet food palatants.

Pet Food Palatants Liquid Coating Solutions

Pet food palatants can be derived from plant or animal proteins. Animal-based liquid palatants can be produced through heat, enzymes, or acids to create a thick gravy-like slurry. This slurry is usually an oil- or water-soluble suspension. It may contain suspended solids, and it may also be highly viscous, hygroscopic, acidic and fatty.

During application, palatants are almost always applied with a layer of fat or oil. The fat or oil is applied first, given time to settle, and the palatant is applied. If these layers are not applied properly, the palatants can become encapsulated in the fats, or the palatants will not adhere properly.

Spray Nozzle Clogs

Applying liquid palatants often involves the use of spray nozzles. However, thick suspensions can quickly clog spray nozzles. To prevent this, the spray nozzle pump should be capable of application at both high and low flow rates. It is also important to monitor the pressure during pumping. If the pressure builds up, the spray nozzles have probably clogged and the coating will not be uniform. For this reason, it’s also helpful to observe the spray pattern and verify that the liquid coating system is working properly.

Another solution to this common problem is removing the need for spray nozzles all together. Some liquid application systems use spinning disks to atomize the liquid and therefore do not need to be monitored for clogs. These liquid application systems are not suspect to back-pressure buildup, and can be highly effective in applying fats, oils and other challenging suspensions.

Back-Pressure Build-Up

Liquid palatants are typically used at a relatively low percentage rate between 1-4%. To maintain this level, the pump must be able to work accurately and consistently. Pressure build-ups, as previously mentioned, can cause problems with the pump. Positive displacement pumps are capable of pumping against back-pressure, so these will help to keep application rates consistent. The pump should also be designed to handle materials with low lubricity and high viscosity, or they will wear out quickly and require frequent maintenance.


Equipment used in the application of liquid palatants must be able to withstand acids. This includes the pump components and application system. Over time, acids will wear down equipment that is not designed for this purpose. Food grade stainless steel equipment will generally withstand the acidity in palatants and last longer than other materials.

Oxidation and Storage

When fats and oils interact with oxygen, lipid oxidation occurs. This causes the lipids to break down into other components, such as hydroperoxides and aldehydes. Ultimately, this degrades the appearance, nutrition, taste, texture and odor of the palatants and the pet food. While lipid oxidation can and does occur at every stage of production, transport, storage and use, reducing oxidation as much as possible at the processing stage is essential for maintaining the quality of the palatants prior to sale. Proper storage for the palatants can help to decrease lipid oxidation. The palatants and oils should interact with the air as little as possible until they are applied, and then the product should be sealed within the package.

Storage temperature is another important consideration. Liquid palatants are easier to pump at a higher temperature, usually between 70-110F. However, prior to application, the palatants should be stored at the manufacturer’s recommended temperatures. Separation can also occur in the tank. Agitation in the tank can keep the suspension homogenized.

Working with liquid pet food palatants can be challenging, but these additives play a vital role in producing pet foods that are both nutritious and appealing to pets. Optimizing the palatant storage and application system—and being aware of potential problems—can help to increase system efficiency and product quality. In our next blog post, we’ll address application challenges and solutions in dry pet food palatants.

Optimizing Pet Food Production with Palatants

pet food palatants

The ultimate goal in pet food production is to give companion animals the nutrition they need to stay healthy and live long, happy lives. However, even the healthiest, highest-quality pet food won’t be effective if pets don’t want to eat it. This is where palatants come in. Pet food palatants give all types of pet food the taste, aroma and texture that pets crave. Pet food palatants have changed over the years, improving pet food and processing, but also presenting new challenges.

What Are Pet Food Palatants?

Dogs use 1,600 taste buds to detect which foods are edible and good for them. Cats use 473 taste buds. Both animals can discern between different flavors, such as sour, bitter and salty, and this helps them determine what they should eat or what they want to eat.

Pet food palatants are designed to mimic the sensory experience a dog or cat experiences from their natural food source, mainly meat. This makes pet food more appetizing to pets. Palatants can be dry or wet, and they are often combined together. They are used in dry and wet pet food varieties, as well as treats, rawhides, tablets and more. They can be derived from animal or plant proteins.

The first pet food palatants were called “digests.” They were enzymatically broken down into dry proteins and added to pet food. Palatants have changed a great deal over the years, and continue to play an important role in making nutritious pet food enticing to pets.

The Application Process

The process for properly applying pet food palatants is important to ensure they are absorbed by the product. Internal palatants may be added to the product itself during processing and also added as a coating. For the coating to adhere and absorb properly, a layer of fat or oil is distributed over the product. Then, the liquid palatants are added, followed by the dry palatants.

Finding the Right Pet Food Palatants

The first challenge in pet food palatants is finding the right palatants for the mix. Some palatants are formulated to be much richer in flavor, scent or texture, while others are more mild. Different palatants also offer different protein and nutrient content, depending on their source and how they are processed.

To find the right pet food palatants, pet food processors and researchers consider the following:

  • The palantant richness compared to the richness of the pet food.
  • Palatant composition, including protein content, nutrient content, salts, etc.
  • The palatant thickness, suspended solids and processing equipment.
  • Product claims, such as plant-based, grain-free, natural, low-fat, non-GMO etc

It’s important to consider the end result of the pet food product as well as the application process of the palatants. Since palatants are made from fats and oils, they can more easily cause problems with coating equipment.

Testing Pet Food Palatants

The best way to assess whether or not pet food palatants actually make pet food appetizing to pets is to test them. This is usually conducted through a bowl test. A dog or cat is given two different pet foods, and the animal’s reaction shows how well the palatants work.

Though the bowl test may seem straightforward, researchers must take a few important considerations into account. For example, the way a pet initially reacts to the food may be different from their ongoing reaction. A pet may be initially drawn to one type of food, dislike the taste, and then try another. Dogs and cats also have different eating habits that change the bowl test measurements. While dogs will eat their food more quickly, cats will eat and return to the bowl multiple times. Researchers study these reactions and many other factors when considering the effectiveness of pet food and pet food palatants.

Trends in Pet Food Palatants

As pets have become increasingly important in their owners’ lives, owners are seeking foods that can help their pets lead longer, healthier lives. Pet owners are increasingly looking for pet foods that are more natural, contain more wholesome ingredients, and provide better nutritional support. The market for products with “clean” labels—containing no meat byproducts, allergens, artificial flavors, colors, etc—and fresher ingredients has grown. Pet food palatants are still an important part of these products, however keeping the products fresh has introduced new challenges. These fresh or raw ingredients are more difficult to protect from oxidation and spoilage. Pet food processors and equipment manufacturers are developing new strategies to support this growing market.

Pet food palatants play an essential role in pet food production. Different types of palatants also present different advantages and challenges. In our next blog posts, we’ll discuss equipment challenges and solutions when applying pet food palatants.

Common Recall Risks in Pet Food Processing: Part II

common recall risks in pet food processing

In our previous post, we discussed a number of recall risks in pet food processing, including bacteria, chemicals and heavy metals. In this post, we’ll discuss additional recall risks affecting the pet food processing industry. This includes two of the most common and most dangerous recalls risks; mycotoxins, specifically aflatoxins, and trace mineral inaccuracies.

Common Recall Risks in Pet Food Processing

Mycotoxins, Storage and Testing

Bacteria and chemicals are not the only recall risks in pet food processing. Mold toxins are another common cause of recalls in pet food processing. Molds that grow in a wide variety of grains, seeds, nuts and grasses produce mycotoxins, which are toxic to animals and people. The most harmful among these are aflatoxins, potent carcinogens and mutagens commonly affecting corn. Effects of aflatoxicosis include liver damage, liver failure, cancer, and an inability to process or metabolize nutrients, among other effects. Due to their high toxicity, the acceptable level of aflatoxins set by the FDA is low, at 20 parts per billion for human and pet foods.

Aflatoxins Thriving in Dry Weather

Aflatoxins are common in corn and can be found in a wide variety of products using corn-based ingredients. These toxins are also very difficult to manage, and continue to be a source of recall risks for pet food processors. According to the FDA, “In 1998, 2005, 2011, and 2013 aflatoxin
contamination of dog and cat food resulted in illness, dog mortalities, and extensive recalls of
affected dog and cat food.”

While many harmful molds and toxins proliferate during warm, humid, wet conditions, aflatoxins are particularly difficult to manage because of their unusual tendency to thrive during hot, dry conditions. Aflatoxin risks are high in 2020 due to hot, dry weather across regions with high corn and grain production. Other damaging incidents, such as wind storms, hail and insect damage has made crops more susceptible to aflatoxins.

Relationships With Suppliers Are Key

This pet food recall risk is also difficult for pet food processors to manage. Aflatoxins are resistant to operations like cooking, which kill other contaminants. Reducing the risk of aflatoxins mostly falls on grain harvesters and suppliers. Improper storage, testing, drying and handling before and after harvest can cause grains contaminated with aflatoxins to enter the pet food supply chain. Pet food processors with a high level of vertical integration and supply chain management and visibility may have the best opportunity to mitigate this problem. Other pet food processors must take care to test ingredients for toxins and maintain close partnerships with reliable suppliers. Facility managers must also take care to prevent ingredient mixing; mixing clean grain or ingredients with contaminated ingredients is not a sufficient solution to reduce the level of aflatoxins.

Trace Minerals and Inaccurate Recipes

Both humans and animals require a number of trace vitamins and minerals for optimal health. Pet food processors may use mineral powders or liquids to give pet food the trace minerals and nutrients that animals need to stay healthy. Trace vitamins and minerals may come from organic or inorganic sources. The source can impact whether or not the substance can be effectively absorbed. In many cases, an inaccurate recipe can make pet foods harmful to pets, either by using too much or too little of an ingredient.

A Careful Balance

B-complex vitamins, including B-12, riboflavin, niacin, pantothenic acid, thiamine, pyridoxine, and biotin, all effect metabolism, nervous system function, and skin and fur health. Trace minerals, like zinc, manganese, copper, selenium, iodine and iron, play a variety of roles in an animal’s metabolic system, nervous system, immune system, joint and bone health, and much more. All of these vitamins and minerals are required in very small amounts. However, a deficit will start to weaken essential function. Unfortunately, an excess can also cause health problems.

Excessive vitamin D levels are one cause of recalls in pet food processing. In small amounts, vitamin D is essential for absorbing calcium and phosphorus. It’s particularly important for supporting muscle and bone growth in young animals. However, too much vitamin can be toxic, causing illness, kidney failure and death. Many other trace vitamins and minerals have similar, very narrow requirements.

The Importance of Accurate Formulation

Accurately measuring macronutrients is easier, since the tolerances tend to be wider. However, ensuring the right mix of trace nutrients requires careful ingredient understanding, as well as a highly accurate distribution system. As previously mentioned, the organic or inorganic source of the ingredient will play a role in how it is absorbed and how it reacts during processing. Thiamin, for example, can be easily destroyed during some cooking processes. In other cases, an trace mineral may appear in the formula, but the animal cannot actually absorb the inorganically-derived substance. All of these aspects, and many more, play a role in the optimal recipe.

With the right vitamins and minerals selected, a reliable micro ingredient system is also essential. Using too much or too little of these ingredients can have deadly consequences, so it’s essential to keep weighing instruments well-calibrated. Automation at this stage can also help to prevent costly errors, and ensure that a recipe is consistent. Integrating a tracking and tracing system is also important. This way, if an error occurs and a lot contains too much of a trace ingredient, it can be removed or recalled more easily.

Food recalls in pet food processing can come from many different directions, just like recalls in food processing for humans. It is impossible to account for all of these risks 100% of the time. Even the most detailed testing and sanitation procedures can leave invisible toxins, microbes, and chemicals untouched. This is why preventative as well as reactive measures are necessary. Preventive measures, like detailed maintenance, proper equipment design, testing, and hazard analysis and help to stop risks before they start. When contamination does occur, reactive measures like tracking and tracing, and recall procedures will help to reduce harm.

Common Recall Risks in Pet Food Processing: Part I

recall risks in pet food

Even when recall procedures are well-practiced and well-known throughout the company, a recall is still a turbulent time. Sometimes recalls take place due to improper sanitation procedures or a lack of testing, and other times it may simple result from an unfortunate accident. Food for human consumption as well as animal consumption can all face recalls. Understanding the biggest recall risks in pet food processing, and how to mitigate these risks, can help you avoid these instances.

Common Recall Risks in Pet Food Processing

Bacteria and Improper Cooking

Bacteria present perhaps the biggest recall risk in pet food processing, just like food for human consumption. A number of bacteria can harm pets in similar ways as humans, though the risk of human infection from handling pet food is much higher. This is one of the reasons that pet food and food for humans are held to similar sanitation standards.

Just like food for human consumption, pet food is also susceptible to contamination from Salmonella, Listeria, and E.Coli bacteria, the most common causes of contamination and food recalls. Cooking at high temperatures generally destroys these bacteria and makes pet food safe for consumption. However, a number of things can go wrong. Fats and oils can create safe pockets for bacteria during this process, ovens may not reach the right temperature, or contamination can occur at other points during the process.

Wet pet food or treats often contain raw ingredients as well, which presents greater risks of foodborne illness. However, all types of pet food can be susceptible to harmful bacteria. Maintaining and verifying proper sanitation procedures, hazard analysis, testing, and recall procedures can help to mitigate the risk of a bacteria-related recall in pet food processing.

Chemicals and Contamination

One of the most well-known and widespread pet food recall cases was the melamine-related recall in 2007. Thousands of pets around the world sickened and died during this time, and the cause eluded researchers for weeks. The pets showed signs of kidney failure, though the chemical responsible for the illness, as well as which pet food brands were affected, was difficult to pinpoint.

Tracing the Cause

The cause of the widespread illness was ultimately found to be contaminated wheat gluten, rice protein and vegetable protein. These raw materials made their way into many different pet food types and brands, making it difficult to trace and stop the spread. The ingredients were contaminated with melamine, an industrial chemical, and possibly cyanuric acid. Melamine has many uses, including an industrial binding agent, flame retardant, and even a fertilizer. However, the presence of melamine and cyanuric acid caused kidney failure in pets.

How melamine and cyanuric acid got into pet food remains uncertain. Accidental chemical contamination during the processing of wheat gluten, rice protein and vegetable protein may have occurred. Since melamine, cyanuric acid and other additives can increase the apparent protein content of these ingredients, the contamination may have been deliberate, though the effects were unexpected.

Challenges in Detection

Testing is one way to prevent chemical contamination through raw ingredients. Ingredient testing can show the presence of many other contaminants, though it is more difficult with melamine. In testing, melamine mimics the appearance of protein, so it is difficult to detect. With difficult contaminants like this, effective tracking, tracing and recall measures are vital.

Heavy Metals and Pollution

Heavy metals such as arsenic, lead, cadmium and mercury are also causes of recalls in pet food processing. In very small amounts, heavy metals are not necessarily toxic, and may even be helpful, as many trace minerals are. However, in higher concentrations, heavy metals are highly toxic and can have many negative health effects. The FDA provides maximum allowable concentrations of these metals to inform testing and recall procedures.

Bioaccumulation and Heavy Metals

In some cases, heavy metals may find their way into pet food from outside sources, such as paint chips or chemicals. In many cases, however, heavy metals enter pet food in the same way that they enter food for human consumption. This is generally through polluted air, water, and soil. A number of industrial processes generate arsenic, lead, cadmium and mercury as byproducts, which then make their way into the air through smoke and ash, water through effluent, and into soil through dumping or through the water cycle. Vegetation absorbs these metals, and transfers them to other animals, including chicken, beef, and fish. These metals then transfer up the food chain and accumulate inside predatory animals. When heavy metal concentrations are particularly high, accumulation speeds up and can sicken animals faster.

While humans generally consume a wide variety of meats, grains, fruits and vegetables, pets often consume the same ingredients throughout their lifetime. Since pets, like humans, cannot process larger doses of heavy metals, the elements build up in their system over time (bioaccumulation). Toxicity builds up until it creates health problems. When pet foods do not contain high levels of heavy metals, this generally does not impact pets until much later in life, if at all. However, high levels of heavy metals can cause health problems quickly.

Preventing Heavy Metal Toxicity with Testing

The process of bioaccumulation is generally out of pet food processors’ hands. This process can only be reduced by regulating environmental pollution, monitoring potentially hazardous industrial processes and chemicals, and properly cleaning toxic waste and spills. When ingredients are exposed to toxic chemicals or heavy metal contamination, testing is key. High levels of heavy metal toxicity can be shown through proper testing. Raw ingredients, generally animal products though sometimes polluted grains, should be tested regularly. Once again, recall, tracking and tracing measures are also essential.

Preventative measures, such as good manufacturing practices for equipment and product testing can help to prevent these recall risks. However, no system is 100% effective. Reactive measures, such as track and tracing systems and recall simulations, can help to mitigate the damage if a recall does occur. Both of these measures are essential. In our next blog post, we’ll discuss additional recall risks and how to prevent them, including the risk of aflatoxin contamination and trace mineral inaccuracies.

Process Improvements to Increase Efficiency in Pet Food Processing

process verification in manufacturing

Increasing efficiency can mean many things. It might mean decreasing waste, lowering costs, improving speed, or increasing overall production. There are many ways to go about this. These improvements can also be difficult to compare or analyze. In this blog post, we’ll discuss a few of the most readily available process improvements specifically in pet food processing. These improvements can help to decrease waste, improve process speed, and improve overall efficiency at your pet food processing facility.

Process Improvements to Increase Efficiency in Pet Food Processing

Optimizing Liquid Coating Systems

Liquid coating systems present a number of challenges to pet food processing facility managers, as well as opportunities for improving efficiency. Pet food facilities working with liquid coatings that are high in fat content, like many dry pet food processing plants, often struggle with clogs and pressure backups. Liquid coating nozzles can easily become clogged in these situations, requiring frequent cleaning, maintenance and replacements. Overall, this requires downtime and eats into production time. Pressure backups also reduce the equipment’s lifespan. When clogged nozzles do not coat products evenly, this can also result in product defects and losses.

Comparing Liquid Coating Equipment

Finding the right liquid coating process and equipment can increase the efficiency of this process dramatically. Your coating system must be designed to suit your liquid coating product, as well as the surrounding processes. The liquid coating must also have enough time and opportunity to evenly coat the product and properly absorb.

Considering alternative liquid coating solutions can help to optimize coating quality, reduce maintenance, and even speed up the process. Even making slight alterations to the mixing process, such as reducing screw conveyor flights or introducing pitched paddles can increase the mixing action and improve the uniformity of the coating. If the spray nozzles are consistently causing problems, consider a system that bypasses spray nozzles, such as a spinning disk atomizing system.

Automated Micro Ingredient Systems

Some pet food formulas require the addition of micro ingredients, such as vitamins and minerals. A reliable system for adding micro ingredients can help to reduce waste, improve organization, reduce process time, and improve tracing. Adding ingredients by hand introduces the opportunity for waste and error. Automated micro ingredient systems allow you to measure ingredients quickly and exactly. With the right micro ingredient systems and tracking system integration, you can also save time on FSMA-required lot tracking.

Scale Calibration

An important aspect of an efficient micro ingredient system is accurate weighing devices. When weighing small amounts of ingredients, accuracy is essential. Be aware of effects that can make your load cells inaccurate, such as temperature changes, load cell creep, interference, or a lack of calibration. Keep in mind that small mistakes in measurements can add up; a minor weighing error with as little as .5% overuse ultimately means wasting .5% of the total product purchased.

FSMA rules require that pet food processing facilities track and trace ingredients, just like food for human consumption. Automated ingredient systems can help trace ingredients from the start of the process until the finished product. A fully integrated system can keep necessary documentation and also work with your labeling system.

Process Improvement Assessments

Go through process improvements step by step, and compare all the costs and expenses equally. Remember to include not only upfront investment costs on one side of the equation, but also maintenance, training, or installation. On the other side, include all the benefits you’ll receive, such as process speed improvements, reduced waste, decreased downtime, and lowered maintenance costs long term. Take a look at the process improvements and efficiency upgrades that present the biggest opportunities first. Equipment or processes that are causing waste and delays should be examined first, as these will present the biggest opportunities for improvement.

With the right systems, equipment upgrades and process speed coordination, you can optimize the most essential aspects of your pet food processing facility. Assess each process first to find where opportunities exist. Prioritize each improvement, and take them on step-by-step, as opportunities become available.

4 Key Sanitation and Safety Regulations in Pet Food Processing

minimizing risk in food processing

Clean, safe food and a clean, safe work environment are important in processing food for human consumption as well as animal consumption. Many of the rules and guidelines for maintaining sanitation and preventing workplace hazards are the same between both of these environments. Taking precautions to create a sanitary pet food processing plant and prevent workplace hazards also has similar benefits; a good reputation, avoiding expensive fines, reducing downtime and improving efficiency. Be aware of these sanitation and workplace hazards in pet food processing, and you can take advantage of these benefits.

4 Key Sanitation and Safety Regulations in Pet Food Processing


A hazard analysis and critical control points (HACCP) assessment is an essential part of food safety, and a major component of the Food Safety and Modernization Act (FSMA). Manufacturers of food for human consumption as well as animal consumption both have to follow FSMA regulations. FSMA applies to both manufacturers in very similar ways. A good understanding of FSMA regulations and requirements will help you to maintain a clean workplace, prevent contamination, and respond appropriately if contamination does occur.

The FDA outlines a HACCP assessment with the following 7 principles. Keep these in mind as you make your plan.

  • Principle 1: Conduct a hazard analysis.
  • Principle 2: Determine the critical control points (CCPs).
  • Principle 3: Establish critical limits.
  • Principle 4: Establish monitoring procedures.
  • Principle 5: Establish corrective actions.
  • Principle 6: Establish verification procedures.
  • Principle 7: Establish record-keeping and documentation procedures.

2. GMP in Equipment Design

Good manufacturing practices (GMP) are an important part of workplace sanitation that can easily be overlooked. In some cases, GMP can be even more important in pet food processing facilities, since these facilities commonly work with materials that present sanitation risks.
Consider the following GMP and sanitation standards in your pet food processing facility:

  • Welded seams: if machines are not welded properly, fats and oils can find their way into cracks, and breed mold and bacteria.
  • Metal sharps: metal burrs that aren’t eliminated during the equipment construction phase can break off into the product.
  • Rust: steel machines without the right finish can rust and flake off into the product. Stainless steel construction, protective finishes and regular inspections can help to prevent this.
  • Hermetic sealing: control panels, weighing devices and other electronics must be properly sealed to protect the device, but also to prevent bacteria from getting in.

3. Bacteria in Fats and Oils

A number of pet food processing procedures involve working with fats and oils, which present unique challenges in preventing the spread of bacteria. Fats and oils are difficult to clean without the proper cleaning solution, and can also make bacteria more resistant to the cooking process. Keep the following in mind:

  • Thorough cleaning: dangerous bacteria tend to build up in forgotten areas, or build up when cleaning procedures are neglected. Cracks in floors and dirty drains, for example, often harbor listeria bacteria. Be sure to use the right cleaning solutions and tools, so debris are scrubbed off first and come in full contact with sanitizing agents.
  • Proper temperatures: Storing fresh food in appropriately cold temperatures and cooking raw foods at appropriately high temperatures is an essential part of preventing disease. Be aware of conditions that can affect storage and cooking, such as opening a freezer door too often during loading or unloading, or ensuring that fats and oils are not compromising the cooking process.

4. Workplace Hazards

Working with fats and oils also presents workplace hazards. For example, if the pet food coating process is not contained, fats and oils can make their way onto floors, creating slip-and-fall hazards. When these coatings make their way into the air, it also presents air quality problems. Containing this process and preventing fugitive particles from escaping is the best way of preventing these hazards.

Pet food processing equipment can also present hazards to workers if the equipment is not properly maintained, or if the equipment is tampered with. For example, safety grates and stopping mechanisms should never be removed or tampered with. Power cords and connection lines should not present trip-and-fall hazards. Cords and power boxes should also be regularly inspected for damage and a secure ground to prevent electric shock or sparks.

Prioritizing safety, providing time and resources for inspections, and providing clear instructions for how to resolve safety issues is the best defense against workplace injuries. Take a preventative stance, not a reactive one; it should not take a tragic accident or expensive lawsuit to emphasize the need for safety protocols.

Spray Equipment and Coatings: Problems and Solutions

Two spray nozzles and a screw conveyor.

Spray equipment and coatings present a number of challenges to food and pet food manufacturers. Spray coating systems, as well as the coating liquids, can be difficult to work with. Workplace hazards, equipment maintenance problems, expenses, down time and other problems may arise. In this blog post, we’ll discuss some of the most common problems with these systems, as well as some solutions.

Spray Equipment and Coatings: Problems and Solutions

Clogging and Crystallization During Spray Coating

spray coating rotating disk
The mistcoater system eliminates the need for spray nozzles and prevents nozzle clogs.

Many spray equipment systems and coatings are not well-suited for each other. Suspended solids in the coating can clog the spray nozzles in the machine, requiring repeated cleaning and maintenance. Salt and sugar solutions work similarly, creating crystals that clog the nozzle. If the spray nozzles aren’t regularly cleaned, the liquid coating can’t break through, creating problems with uniformity and back pressure (we’ll discuss these in more detail later in the post).


Spray nozzles aren’t ideal for coatings with suspended solids, or salt and sugar solutions. Consider spray equipment can atomize coatings without the need for a narrow outlet. APEC’s Mistcoater uses a rapidly spinning disk to atomize liquid coatings into fine droplets. This eliminates opportunities for clogs and crystallization.

Inconsistent Coating

Different liquid coating characteristics can affect their compatibility with different spray equipment. As previously mentioned, suspended solids and salt or sugar content, as well as liquid percentage and viscosity can affect the uniformity of the coating. As a thick solution moves through the spray nozzles, the high viscosity creates inconsistent flow. Or, some spray nozzles may be clogged, while others continue to work, creating inconsistencies across the product. Some pieces can be coated too heavily, and others might not be coated at all. This means food and pet food manufacturers must take special considerations to ensure uniform coatings across the product.


Spray nozzle coating systems present a variety of challenges in choosing the right coating. A liquid that is too thick or has too many suspended solids can render the entire system ineffective. An atomizing system which removes the need for spray nozzles can provide uniform coating over a longer period of time. Thinning the liquid may also be effective, however this may also affect how well the coating sticks to the product.

Back Pressure Build-up

When crystals and clogs build up on spray nozzles, it causes pressure to build up throughout the rest of the spray equipment. This means the machines require more horsepower to operate, wearing them down prematurely and using excessive power.


Once again, removing the opportunity for clogs provides an easy solution to this problem. When the fat, oil, salt or sugar solution is atomized over a spinning disk instead of being forced through a small outlet, there is no back pressure build up. Regularly cleaning spray nozzles or reducing the liquid’s viscosity can also help to reduce problems with back pressure.

Workplace Hazards and Sanitation

Spray equipment and coatings can also present a number of workplace challenges. Coatings on food and pet food not only get sprayed onto the product, but also move through the air, stick to the floor, stick to workers, equipment, and any exposed surface. When working with fats and oils, this also introduces sanitation problems. These coatings can make their way into cracks in the floor, small spaces on machines, and other areas that are difficult to clean. This creates perfect opportunities for mold and bacteria to build up. Sprayed coatings in the air and oily, slippery floors also create workplace hazards for employees.


The best solution for these sanitation problems and workplace hazards is enclosing the spray coating system. The Mistcoater spray coating system is fully enclosed, keeping the coatings inside and preventing them from entering the air or sticking to other surfaces. Enclosing spray coating systems can help to dramatically reduce the amount of housekeeping and safety measures needed to keep your workplace safe and sanitary.

Consider your spray equipment and coatings carefully in the equipment design phase, and you can avoid many of these issues. If you’d like to learn more about the fully-enclosed Mistcoater spray coating system for your food or pet food products, contact us.

Liquid Coating Processes for Uniform Snack Coating

Whether for flavor, vitamin content, shelf life, or texture, liquid coating is the preferred application method for many cereals, snacks, pet food mixes, and more. Though this provides a number of efficient, time-saving advantages for snack coating, it can introduce some challenges if the process isn’t correct. Consistency and uniformity in liquid coating are two of the most common challenges in pet food and snack coating. With careful process design considerations, you can find the right process for your coating and substrate.

Liquid Coating Processes for Uniform Snack Coating

Before Application: Measurement

A standard mass flow system.

Before applying the liquid coating to the substrate, it’s essential to accurately measure the flow of each material. There are several way to do this, and which you choose will depend on the accuracy you require, moisture or temperature conditions, the composition of the carrier ingredient, and the layout of your facility. The carrier ingredient will be the “master flow” and the liquid coating process will depend on it, making accuracy even more important. You may need to consider potential flow problems at this stage.

You might choose the following flow measurement systems for continuous snack coating:

  • Volumetric: A screw conveyor, rotary feeder, or belt conveyor measures solid flow through RPMs (or Hz). A nutating disk, positive displacement pump, piston pump or turbine measures liquid flow through RPMs (or Hz) or pulses. Volumetric measurement is sensitive to changes in density, and not recommended for applications with high accuracy. Calibrate often to adjust for elevated temperature or moisture content,
  • Mass flow: Mass flow measurements have more versatility, with a variety of measurement systems. Weigh belts, weigh screws, impact scales, and nuclear gauges more accurately measure flow through RPMs and weight simultaneously.
  • Loss in weight: This measurement system works similarly to mass flow systems, however it measures weight as the material flows out. A garner hopper and scale hopper work in unison to take accurate measurements in a continuous flow system. This system is also quite accurate, however a facility’s height restrictions may be problematic. The scale hopper operates in weight exception mode during re-filling to accommodate continuous operation, and this should not exceed acceptable tolerances.

Liquid Coating Applications

With the measurement system determined, you have the right amount of liquid coating and substrate, but you still need to decide how to apply an even, consistent coating in the continuous process. You might use a screw conveyor, rotating drum, or mist coater.

Screw Conveyor and Spray

liquid application screw conveyor
Two spray nozzles and a screw conveyor.

As the screw conveyor moves the substrate, spray nozzles apply the liquid coating. In a simple screw conveyor very little agitation of the product takes place. To get a uniform coating, the substrate will require agitation. Some of the screw conveyor flights can be cut away to form more of a ribbon to agitate the product while moving it forward. Lifting flights and paddles on the screw conveyor will provide more movement, and there should be enough space for the material to tumble through.

The tumbling action through the screw conveyor must be gentle for fragile materials, which can slow down the process. Liquids moving through the spray nozzles can also present problems. If the liquid flow rate changes a great deal, then additional spray nozzles may be needed so the quantity being sprayed does not drop below or go above the rated capacity for flow and pressure, which can affect the quality of the atomization. If the liquid has suspended solids, spray nozzles will easily clog.

Rotating Drum and Spray

This liquid coating process works similarly to the screw conveyor, except the material moves through an open-ended cylinder. Flights lift and tumble the material, and spray nozzles coat the material as it moves through. This method is generally gentler and ideal for fragile snacks or foods.

Since the rotating drum is open on both sides, fugitive liquid and dust can quickly become an issue. Without proper ventilation or cleaning, the liquid or dust can create slip and fall hazards, unpleasant or hazardous working conditions, or it may damage equipment. The required length of the drum may also be a concern for facilities with limited space.

Spinning Disk and Mist Coating

liquid coating spinning disk atomization
Liquid application through spinning disk atomization.

During this process, the material moves across a spinning disk and flows over the edges. As it falls, the liquid coating hits additional disks moving much faster in the opposite direction below. The liquid atomizes into a mist that coats the material as it falls.

Atomization through spinning disks solves many of the liquid coating problems presented by spray nozzles. Since pressure is not required for the liquid coating application, density changes and solid suspensions are no longer a concern. This also allows for multiple liquid coatings simultaneously, regardless of changes in density or viscosity. Finally, the system is completely enclosed, which prevents fugitive dust and liquid from escaping.

Finding the right pet food or snack coating process will help you not only increase product quality and consistency, but it can also reduce costs, product loss, labor, and maintenance needs. Always test the process before installation, and work closely with your equipment manufacturer to get the right system.