Processed With Purpose
Understanding Pet Food Processing Methods and their Applications
Introduction
Pet food, as a commercial product, has a long history and has evolved significantly since the first mass-produced products in the 19th century. With growing demand for convenience and advance nutrition, manufacturers have developed various methods to produce pet food. From traditional techniques like extrusion and canning to innovative methods like freeze-drying, pet owners now have a wide range of products to choose from. This factsheet explores these processing methods, with the aim to educate on their benefits, safety and effectiveness and allow pet owners to make informed decisions about their pet’s diet.
Processing in Pet Food and Human Food: similarities and differences
Processing plays a crucial role in both pet food and human food and serves different purposes and outcomes. In pet food, a degree of processing is essential for creating diets that are safe, and nutritionally complete and balanced. These foods are designed to be reliably fed as the primary source of energy and nutrients for the species and life stage they are intended for. Pet food processing methods help to:
- Enhance Nutrient Availability: Cooking and processing can make certain nutrients more digestible for pets.
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Ensure Food Safety: Processes eliminate harmful pathogens, ensuring the food is safe to consume.
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Extend Shelf Life: Techniques like canning and extrusion increase the shelf life without the need for additional preservatives.
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Formulate Balanced Diets: Processing allows for precise formulation to meet the dietary requirements of pets at different life stages.
- Consistent Quality: Many processed foods provide consistent quality, palatability, and appearance.
In both human nutrition and pet food, processing involves the addition of ingredients and the application of techniques such as chopping, cooking, or freezing to transform fresh food into products that are more convenient and have a longer shelf life.
However, unlike pet food, processed human foods are generally not intended to be ‘complete’ diets. This is why people are advised to follow a varied diet and include a range of foods and products to achieve an overall balanced intake of nutrients. Due to processing methods and the addition of nutrients to make complete products, pet food has been compared to ‘ultra-processed’ foods (UPF) in human nutrition. However, there is no evidence linking any format of complete pet foods to the adverse effects seen with overconsumption of some UPFs, such as processed meat and sweetened soft drinks, which are found in human diets.
Examples of Processing Methods in Pet Food
Mixing and Blending
Mixing and blending involve combining various ingredients to create a nutritionally balanced feed for animals. This process ensures even distribution of ingredients throughout the mix, especially smaller inclusions like vitamins and minerals, thereby maintaining consistency across mouthfuls and batches. Mixing and blending are essential in all pet food production to deliver the right balance of nutrients for optimal animal health.
Grinding and Mincing
Grinding and mincing involve using specialised machines to reduce ingredient size, creating a finer, more uniform texture. This step is essential for preparing ingredients for optimal mixing, cooking, or further processing. Beyond size reduction, it ensures a consistent particle size, promoting a more homogeneous mix and consistency across batches and/or mouthfuls.
Extrusion
Extrusion is one of the most common methods used to produce complete dry pet food, or kibble. In this process, carefully selected ingredients are mixed, ground, and then pushed through an extruder where heat and pressure cook the food. The mixture is then cut into the desired shapes and sizes before being dried—removing moisture from the food to prevent microbial growth—and coated with beneficial fats or palatants to enhance nutrition and palatability. Kibble provides a safe, convenient, affordable, and nutritionally balanced option for pet owners, meeting pets' energy needs while maintaining food safety.
Millions of dogs and cats have been safely and happily fed extruded kibbles for over 60 years. Some kibble products also support dental and oral health in pets, such as dental health diets that use specialised kibble technology to reduce plaque and tartar buildup or formulations with specific ingredients to support oral care.
Baking
Baking is an alternative cooking method in which ingredients are mixed into a dough and baked at lower temperatures than those used in extrusion. This process results in a denser product that may be preferable for some pets.
Sterilisation (e.g., canning and retorting)
Sterilisation involves cooking ingredients in sealed containers at specific temperatures, effectively destroying any pathogens and locking in flavour and moisture. This process keeps the food safe and edible for extended periods without preservatives. It also allows for a variety of textures, such as jelly or gravy meals, pâtés, and stews, providing pet owners with options that cater to their pets' preferences. Additional benefits can include higher moisture content to support hydration.
Many wet food products, commonly available in pouches, trays, or cans, are produced using this method.
Pasteurisation (Cooked then Refrigerated or Frozen)
Pasteurised products are cooked at lower temperatures than sterilised products like canned or extruded foods. While pasteurisation effectively destroys pathogenic bacteria and spoilage microorganisms, it does not eliminate spores or the most heat-resistant strains, so these products must be refrigerated or frozen. Like extrusion and canning, pasteurisation is a versatile method, allowing for various styles of complete and balanced pet foods and treats, such as chubs/rolls with diverse textures, pouches with visible fruits, vegetables, and meats, and treats for dogs. Since no preservatives are added, refrigeration or freezing is essential to prevent spoilage.
Semi-moist production
Semi-moist pet food is made by combining main ingredients with humectants (substances that attract and retain water molecules) to help keep the food moist and inhibit the growth of harmful bacteria. Ingredients are cooked at controlled temperatures, extruded into shapes, and then quickly cooled to create a uniform, safe texture. Humectants like glycerine or propylene glycol are added to maintain softness, reduce moisture loss, and extend shelf life without refrigeration. Preservatives are also commonly used in this type of pet food. The result is a palatable, soft-textured food that provides a convenient option for pet owners, bridging the gap between dry kibble and wet food.
Freezing
Freezing is a preservation method for pet food that involves lowering the temperature to below freezing to halt bacterial growth and preserve the food’s nutrients. This process helps maintain the food’s original texture, flavour, and nutritional content while extending its shelf life without the need for preservatives. Frozen pet food products must remain in freezers throughout transport, retail, and while stored at home, until defrosted according to the product's instructions for feeding to pets. Like other preservation methods, appropriate handling and storage are essential to maintain food safety and hygiene.
Freeze-Drying
Freeze-drying is a technique where food is first frozen and then placed in a vacuum chamber, where moisture is removed through sublimation (the process of ice turning directly into water vapour). This method helps retain the food's nutritional value and flavour while making it lightweight and shelf-stable. These products do not undergo thermal processing, so while the removal of water helps reduce microbial activity, microbes may be temporarily deactivated, and any spores may still remain. This is an important consideration for handling and hygiene when storing and feeding the product. Freeze-dried pet foods and treats are made using this technique and are popular among pet owners seeking uncooked yet conveniently packaged options.
Air-Drying
Air-drying involves slowly drying pet food ingredients at lower temperatures. Unlike freeze-drying, it doesn't involve freezing but gradually removes moisture while preserving nutrients. This method results in a softer texture compared to kibble but remains shelf-stable.
Air-dried pet foods are typically found in premium lines of raw-inspired diets, offering a middle ground between cooked (e.g. kibble or canned) and raw pet food.
Cold pressing or pelleting
Cold-pressed pet food is made using a unique process where ingredients are combined, minimally heated, and then pressed at low temperatures to form compact pellets or shapes. Unlike traditional extrusion methods, which use high heat and pressure, cold pressing results in a finished product that retains more of the raw ingredient’s characteristics. The outcome is a dense pet food that mirrors the nutritional profile of raw diets while being shelf-stable and easy to store.
In the case of cold-pressed pellets containing Animal By-products (ABPs), these ingredients are heat-treated before being incorporated into the pelleting process. Therefore, while the final product may be cold-pressed, some ingredients may have been heat-treated prior to production.
Packaging
Packaging techniques help prevent contamination, damage, and exposure to environmental factors (like moisture, light, and oxygen) that could spoil the product.
Pet food packaging, especially for specialised products, is designed to maintain freshness, protect nutritional quality, and extend shelf life. Common materials include multi-layered pouches, moisture-resistant bags, and resealable zippers to shield contents from air, light, and humidity. For most pet foods, airtight seals or vacuum packing are used to prevent spoilage and oxidation, keeping the food fresh without refrigeration. Labels on the packaging offer essential information, such as ingredients, nutritional content, and storage instructions, while also safeguarding the product from physical damage and contamination.
What Are Processing By-Products?
The Maillard reaction, a natural process that occurs in all cooked foods, is responsible for the browning and rich flavours we associate with roasted, grilled, or baked food items. During the processing of pet food, particularly when high heat is involved, certain compounds known as processing by-products can form.
These by-products result from processes like cooking, sterilisation, or chemical preservation, which are crucial steps to ensure nutritional quality and avoid spoilage during shelf life. Some of these compounds, such as Advanced Glycation End-products (AGEs, sometimes referred to as glycotoxins), naturally occur in both human and animal bodies, and are also produced during everyday cooking, such as when toasting bread or grilling meat.
Scientific research and safety evaluations are routinely conducted on pet food, and current evidence shows no direct links between AGEs, at the levels found in processed pet food, and adverse health effects in companion animals