A complete and balanced pet food formulation is a tall order. Processors must consider a multitude of factors that can ultimately make or break a pet food’s ability to consistently deliver the desired nutrients. Ingredients, processing method, packaging, storage and animal biology all must be understood and addressed.

Unlike most food produced for humans, diets for our pets regardless of the form — dry kibble, wet diets, or refrigerated chubs — must be “complete and balanced” as defined by the Association of American Feed Control Officials (AAFCO) nutrient profiles for canines and felines. “This simply means the diet must contain all of the required protein, amino acids, fat, fatty acids, vitamins and minerals required by the pet for a healthy life,” explains Eric K. Altom, Ph.D., technical nutritionist, Balchem Animal Nutrition and Health, New Hampton, N.Y.

“When you combine all the ingredients together, some nutrients are stable, while others are very fragile.  Some ingredients and nutrients can enhance the diet’s palatability and other ingredients may negatively impact product freshness and acceptance by the pet. So, creating a proper recipe, from a formulation standpoint, can be extremely challenging.”

“There’s much more to it than a blend of ingredients,” says Jeff Alix, global marketing manager pet nutrition, DSM Nutritional Products. “Vitamins, carotenoids and other micronutrient ingredients come in many forms which include various chemical structures, potencies, formulations, and particles ranging in size, density, shape and electrostatic charge. Formulation is dictated by the target species, nutrient stability through processing and shelf life, optimum nutrient dispersion throughout the finished product, which affects the critical nutrient activity per serving, and sometimes even the physical attributes of the finished product.”

A quality recipe and quality manufacturing are paramount and require a collaborative relationship between the pet food company, nutritionists with expertise in animal nutrition, process engineers and suppliers. “As a nutritionist, I can select the best ingredients and create a wonderful recipe that I know is optimal.  However, if the ingredients are not stored properly, if the ingredients are not blended properly and if the finished diet isn’t properly extruded, stabilized and coated with fat and natural preservatives and packaged correctly, you will not deliver the expected end-product,” Dr. Altom explains. “Your team will need a talented process engineer with the technical knowledge to deliver a premium finished product with limited batch variation, controlled lot variation and reduced bag-to-bag variation.”

“Every pet food application is unique, facilities are different and the level of support required varies,” says Jim Mann, Nutrisurance global product manager, Kemin, Des Moines, Iowa. “It’s vital to partner with the proper companies who can provide technical expertise, laboratory testing services, product application equipment and product training.”

Digesting differences

The digestive systems of cats and dogs aren’t identical, but they’re similar in the way they process food and absorb nutrients. There are some important differences, however, when it comes to specific nutrient requirements. “Dogs are very good at producing some of their own necessary nutrients where cats do not,” says Frank Monteleone, president, FoodSafe Technologies, Charlotte, N.C. “For instance, cats are obligate carnivores, and are very dependent on available animal proteins in their diets. Unlike dogs, cats cannot convert amino acids into taurine, so cats need taurine added to their diet. Cats should not be fed dog food.”

Also, dogs can make vitamin A by extracting beta-carotene from other nutrients that are present, but cats need vitamin A supplied in their diet. Another important difference is their requirement for protein. Ingmar Middelbos, Ph.D., senior technical services manager, IsoNova Technologies, St. Louis, Mo., says, “Because cats continually break down protein at a high rate, they require higher levels of total protein than dogs. Cats also lack enzyme efficiency to generate arachidonic acid, a long chain fatty acid that cats need in their diet, but adult dogs don’t.”

Knowing what nutrients must be included for each species is the place to start. Protecting nutrients through processing and storage is the next hurdle.

Nutrient preservation

“Some biologically critical nutrients are very stable and do not require over-formulation to ensure targeted delivery to the animal.  Choline chloride would be one such nutrient. It has a lot of physiological benefits for pets.  Unlike many nutrients, Choline chloride is stable during cooking processes and does not interact with other nutrients,” Dr. Altom explains. “Chelated or proteinated minerals are highly bioavailable to the animal and can be beneficial options in complete-and-balanced formulations because they are sequestered from some of the degradative chemical reactions in a complex diet matrix such as oxidation.”

In formulation and production trials, nutrient losses over time are evaluated to make sure that, at the end of shelf life, nutrients are available and the product is still nutritionally balanced. “Vitamins are the biggest challenge. They are sensitive to both processing and shelf life. Proteins and fats oxidize over time which can accelerate vitamin loss. Reducing pro-oxidative components like ash and using inherently stable ingredients like egg powder can help with shelf stability,” Dr. Middelbos says.

Finding the right solution for each unique application requires formulation and ingredient know-how, along with processing knowledge to minimize nutrient losses, limit known interactions, preserve product quality and stability and enable absorption once the product is consumed. Manipulating molecules provides a few of the solutions.

“Organic trace minerals will survive the harsh conditions of processing by being complexed to a polysaccharide compound,” explains Jack Garrett, Ph.D., director research and technical support, QualiTech, Chaska, Minn. “The polysaccharide compound protects the trace mineral from negatively interacting with other nutrients until it goes through the stomach and arrives in the intestines. The change in pH in the intestines triggers the release of the mineral for absorption.”

“Depending on the vitamin molecule, vitamin manufacturers offer chemically stabilized vitamins and micronutrients or use encapsulation to physically protect them,” Mr. Alix says. “Across all formulations, the essential nutrients vitamin A, vitamin D and carotenoids are some of the most heat-labile and sensitive to oxygen.  For dry pet foods, excessive heat and oxygen are the greatest challenges these nutrients face.  In high moisture pet foods, the essential nutrient thiamine, vitamin B1, represents an additional safety challenge due to its sensitivity to high temperatures and pH.”

Nutrient bioavailability must be considered when creating a complete-and-balanced diet for pets, but if a pet won’t eat the food, the product cannot deliver the proper nutrition. Aroma and taste drive product acceptance for pets. External dietary fat application, moisture content, finished diet preservation technologies and selected palatants are all critical factors that determine aroma and taste. “Pet food must be fresh and shelf stable without mold and rancidity and meet the on-package ‘Best Used By Date’ nutrient guarantees. This is a critical area where beneficial acids and natural preservative systems come into play,” Dr. Altom says. “The broad range of pet diets today requires processors to expand their methods to deliver a stable product that pets will readily enjoy and meet ingredient declarations that are acceptable to the pet owner.”

Formula opportunities, challenges

Increased use of fresh and frozen meats and novel grain sources has led to the need for new solutions. “Historically, many pet foods were composed of underutilized feed or food-industry by-products, which delivered excellent nutrition at an attractive economic value,” Mr. Mann explains. “Over the past two decades, however, the pet food market has become extremely dynamic and diets have more closely resembled human food. The trend of pet humanization is largely responsible for this and continues to drive innovation into pet food stabilization options that are more natural.”

Many of the novel ingredients can require innovative antioxidant solutions to maintain palatability and stability. “Cats and dogs are much more sensitive to oxidation compounds than humans. Changes in ingredient composition and product format of pet food and pet treats require new antioxidants,” Mr. Mann adds. “This is driving pet food manufacturers and consumers alike to look for cleaner, more natural alternatives to synthetic antioxidants, such as BHA and BHT.”

Product formulation is about balance. Any shift in ingredients will require a counterbalance solution. “The by-product of grain-free formulas is more animal protein, which results in a potential oversupply of protein and an imbalance in amino acids in the formulation. Or if pea protein is used as a source of starch in lieu of grains, it is very unbalanced in key amino acids and needs to be paired with something like egg to correct that imbalance while still controlling ash,” Dr. Middelbos says.

Dr. Altom points out, “With raw and dehydrated products some of the nutrients may be more stable and go through a more gentle process, but the finished product may be at greater risk of exposure to pathogenic bacteria without effective processing controls.”

Any time there is protein in a process that is susceptible to bacteria, killing as much bacteria as possible on the protein as early as possible is the goal. “If you kill the bacteria early you won’t have to worry about continually measuring pH on the protein as it goes through the process all the way downstream,” Mr. Monteleone says. “Enriching minerals and pH organic acids don’t go well together because a mineral will just knock out a pH organic acid. So, the earlier you start killing the bacteria, the more efficacy you can provide before the addition of nutrients, especially enriching vitamins and minerals that would counter act the pH of acids. These two steps should be separated in time and process.”

A subtle approach is best

Consistently delivering nutritious food to pets is a complex process in which every ingredient must play well with others, and each step must be properly calculated. “We recognize that every existing diet formula has gone through a painstaking amount of science to get where it currently is,” Mr. Monteleone says. “To tweak it requires a lot of validation. On the antioxidant side, we start with the most subtle approach first, so we don’t interfere with the existing science and the effort that went into the formula. On the antimicrobial side, you want to confront pathogens early in the process, with strength.”

Dr. Altom adds, “There is often a steep learning curve to produce a premium food for our pets. Those of us involved with formulating pet food who are nutritionists, veterinarians and processing technologists, work with people who are often following their passion.  We are extremely fortunate to help fuel their passion and provide some baseline education along the way.” He says, “Being able to solve these unique nutrition and processing challenges is why most of us get up in the morning. I think you’ll find that most of the technical professionals in this industry love dogs and cats. We share our lives with our pets and we feed the products our teams develop. We have a vested interest in the safety of pet nutrition products and desperately want to enrich their lives with great nutrition.”

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