Evaluating the Shelf Life of Ingredients in Pet Foods
Cats and dogs make up approximately 184 million of the total number of pets owned by households in the United States. According to the American Pet Products Association, sales of pet food and treats were US$42.0 billion in 2020 and US$44.1 billion in 2021 in the US market. Animal materials deemed inedible for human consumption are processed for use as pet food and treats. The types of animal by-products that are rendered include offal, fat, blood, bones, meat trimmings and viscera. The fastest growing categories in the pet food industry are raw, frozen, and freeze-dried. Sales of raw pet food increased by 196% and frozen pet food increased by 235% between 2012 and 2016. Raw, frozen and freeze-dried products are assumed to have a long shelf life. The main ingredient in pet food is meat, with considerable amounts of water and high concentrations of fat and protein. However, extended storage and freezing times, multiple freeze-thaw cycles during transportation and storage of raw frozen foods, and high temperature applied to melted protein meals can impact meat quality, damage proteins and amino acids, make proteins less digestible and increase the level. of oxidation products. Therefore, assessing the quality of the fat and protein content of pet foods is essential to ensure a nutritionally complete diet.
Lipid Oxidation in Pet Foods
Rendered animal protein meals, which are used in extruded pet food products, provide higher quality protein than raw meat. The fat is separated from the cooked material during the rendering process; however, some remaining fats can oxidize and become rancid after prolonged storage if not protected. Therefore, it is essential to understand which antioxidants are effective in controlling oxidation. Oxidized pet food has an impact on animals that consume the food. For example, puppies fed an oxidized diet have lower weight gain, lower serum vitamin E, lower linoleic acid, and slower bone formation. Additionally, raw frozen pet food can go through multiple freeze-thaw cycles during transportation, purchase, and storage, which can lead to oxidation of the product. In addition to the number of freeze-thaw cycles and storage time, the type of antioxidant used will affect the degree of oxidation that occurs in a product.
Protein Oxidation in Pet Foods
Fresh meats and meat meals are two raw materials used as protein sources in dry pet food. Fresh meats are obtained from meat rejected as unfit for human consumption without any sign of disease transmissible to humans, while meat meals are obtained from animal parts such as hooves, horns, hair and feathers that are not consumed by humans. Meat meals undergo an intensive industrial process using high temperatures, 115–145°C (240–290°F) as a method to separate and melt the fat from the solids. High temperature can damage proteins and amino acids, making them less digestible, cause oxidation of proteins, partial degradation of raw materials and alteration of organoleptic and nutritional properties of pet food products. In addition, improper storage conditions increase the proliferation of microorganisms, degrade organic components and develop harmful products, such as biogenic amines.
Improved shelf life and product stability
Pet food processors and manufacturers must prevent microbial growth, control pH, and use traditional or natural additives to prevent oxidation to improve the shelf life and stability of pet foods .
Effective preservation of microbial shelf life is a critical factor in the long-term commercial success of pet food. The risk of microbial growth (yeasts, molds, bacteria) is lower in dry products than in semi-moist products. In addition, a reduction in pH is necessary to inhibit microbial growth. Acid ingredients or acid salts can be used as food additives to achieve the target pH. However, the main issues with using additives include identifying the most appropriate additive for the specific product, determining the appropriate dosage, and finding the best location to add them to ensure proper distribution. . Antimicrobial agents include acids such as acetic acid, benzoic acid, and citric acid, as well as non-acids such as nitrites and sulfites. Factors to consider when choosing the best antimicrobial agent for pet food include acid number, presence of other inhibitors such as salt, smoke, sugar, moisture content, solubility, storage time and temperature conditions.
Delaying the onset and rate of lipid oxidation by adding antioxidants is an effective, practical, and economical strategy that can be used to improve product stability and shelf life. Lipid oxidation can lead to nutritional deterioration and produce undesirable flavors, colors and toxic compounds that often make foods less acceptable to pets. Antioxidants work by scavenging free lipid radicals, controlling transition metals, quenching singlet oxygen, and inactivating sensitizers. Hydrogen atoms are donated by antioxidants to free radicals and therefore convert them into more stable, non-radical products. Antioxidant activity depends on various factors, such as temperature, pH, degree and amount of unsaturated fatty acids, as well as the presence of oxygen and metal ions.
The goal of veterinarians, nutritionists, pet food manufacturers and pet owners is a long and healthy life for dogs and cats, using wholesome pet foods. Extended storage and freezing times, multiple freeze-thaw cycles occurring during transportation and storage of raw frozen foods, and the application of high temperatures during food processing can impact food quality for pets, increase the level of oxidation products, damage proteins and amino acids and make them less digestible. Safe and healthy pet food comes from safe ingredients from well-vetted suppliers; therefore, a better understanding of ingredients and the application of methods that can be used to improve the shelf life and stability of pet food is an important part of pet food production.