Maintaining freshness through the shelf life of a product not only meets the discerning expectations of today’s pet parents, but also prevents waste and even sickness. It’s all about starting with quality ingredients and effectively preparing and packaging them in a manner that meets the shelf-life demands of distribution and pet owner habits.

“Shelf life is important for all forms of pet food, especially when considering nutrient degradation,” said Lisa Schole, co-owner, Evolve Consulting Group, Crofton, Md. “Ensuring a proper shelf life protects the vitamins, minerals and additional guarantees made on the product label.”

Amy McCarthy, vice president of pet nutrition, ADM Animal Nutrition, Quincy, Ill., said, “Two top concerns for pet food and treat manufacturers are microbial spoilage and oxidation. Dried foods and treats are susceptible to oxidation and mold, which can result from issues like incorrect storage or high water activity. If seal integrity of canned foods is compromised, microbial spoilage may occur, potentially leading to swelling or bursting of the packaging. Frozen and refrigerated foods must remain at the appropriate temperature throughout the cold supply chain to ensure safety and quality for the product’s full shelf life. Additionally, biodegradable packaging has sustainability appeal, but it may offer less protection against oxygen and moisture.”

Whether a product is wet, dry or chewy, to maximize shelf life, you must start with quality raw materials. The less moisture in the ingredients when they are delivered to the pet food manufacturing facility, the easier they are to work with in terms of delivering on quality, as moisture invites deterioration.

“Manufacturers in rendering and pet food processing have many decisions to make when considering ingredient preservation and creating pet food products,” said Jim Mann, global platform manager, antioxidants and food safety, Kemin Industries, Des Moines, Iowa. “This includes how to prevent microbial growth, control pH and whether to use traditional or natural additives to prevent oxidation and improve shelf life and product stability.”

Microbial spoilage must be managed from the beginning to the end. Meat-based raw materials can degrade prior to manufacturing and reduce quality and impact animal health, especially in refrigerated products contaminated with pathogenic bacteria, such as Salmonella and Listeria. And, unfortunately, pathogens are invisible, which is why it is important that manufacturers take proper precautions to ensure safety. Mold, on the other hand, is visible and is reason to dispose of product. Any product that is not sterilized can have mold challenges if moisture or water activity are not controlled.

Heat and container matter

Retorting is the original cooking process to extend the shelf life of low-acid wet foods. The food is heated in hermetically sealed containers — cans were first, pouches and cartons came later — to destroy all spoilage and pathogenic microorganisms, thereby sterilizing the product. Aseptic processing also sterilizes product.

Retorting is a very economical process for manufacturing wet pet foods. However, the downside is that the high temperatures destroy heat-labile vitamins and may negatively impact product quality. It is these drawbacks that have fueled the growth of the fresh and frozen pet food categories, both of which still require proper cooking to destroy pathogenic microorganisms. 

“Kill steps are basic and critical to food safety,” said Rob Ames, senior business development manager, Corbion, Lenexa, Kan. “Using them as shelf-life strategies can have merit and ultimately shrink the ingredient deck (as chemical preservatives are not necessary). Manufacturers should consider secondary shelf life (once the container is opened) and the consequences of packaging failures. This is where ingredients can cover the gap.”

Mann said, “Most of these ingredients are organic acids, or ingredients that produce organic acids. They can work by several mechanisms, either by acidifying the bacterial cells or by destroying cellular membranes.”

These ingredients are key to ensuring the shelf life and safety of refrigerated pet foods. They are especially useful in raw pet foods.

“These products are often less processed with a shorter shelf life, as compared to traditional wet and dry foods,” said Cynthia Rasmussen, business development manager, food protection and preservation, Kerry, Beloit, Wis. “Pet owners are looking for recognizable ingredients, leading more manufacturers to seek ingredients that both protect against microbial spoilage and perfect color, aroma and product palatability. New processing methods have helped improve food safety challenges.”

Vinicio Serment-Moreno, applications and food processing specialist, Hiperbaric, Doral, Fla., said, “Pets can be more resistant to pathogens, but they might inadvertently transfer them to owners through saliva, fur or feces, and owners can also spread pathogens in the kitchen by handling tainted utensils.”

This is where high-pressure processing (HPP) can assist. The HPP system involves the loading of airtight/hermetically sealed packages into an HPP vessel, where they are subjected to isostatic pressure (equal pressure on all sides), disrupting the microbial biochemistry of pathogens and spoilage bacteria, which helps preserve freshness and increase shelf life of perishable foods.

“Applying HPP reduces loads of hazardous bacteria, parasites and viruses, while keeping pet foods safe and nutritious,” Serment-Moreno said. “The HPP technology has minimal impact on the biochemical components of food like proteins and vitamins, ensuring that HPP pet foods meet the nutritional requirements of companion animals with improved sensory quality.”

Errol Raghubeer, senior vice president of research and development, Avure Technologies LLC, Middletown, Ohio, said, “Innovative processors use HPP to expand their distribution chain. In addition, HPP is strongly recommended as a food safety intervention step for raw pet foods. The technology preserves the flavor, texture and nutrients in raw food ingredients, and provides a safe alternative for immunocompromised dogs and cats who would otherwise not be able to eat a raw diet.”

A Pup Above, Austin, Texas, uses the sous vide process to gently cook its fresh human-grade dog foods to ensure safety and quality. Sous vide involves vacuum sealing food in specially designed pouches that get slow cooked in water at low temperatures until fully cooked.

“Our process includes product being quickly frozen just after being fully cooked,” said Ruth Stedman, co-founder and chief executive officer. “Keeping it frozen and closely monitoring our supply chain keeps our products fresh and wholesome for up to one year.”