Vitamin Stability in Pet Food
19 November 2020
By Trevor Faber, Ph.D.
Companion Animal Nutritionist
We ask a lot of the ingredients that we use in pet food. The pet food supply chain can be lengthy and full of challenging conditions. From the barn or field to the pet food manufacturer, pet food ingredients typically go through at least one or more processing steps, such as drying, milling, grinding or nutrient extraction. From there, the ingredients are typically cooked, dried and then packaged to sit on a shelf for as much as 18 months. Throughout this process, the goal is to maintain ingredient and product quality through the addition of antioxidants, controlling water activity, and other preservation techniques.
For most nutrients, the amount of degradation is limited over time. In other words, the nutrient concentrations of the ingredient at time of receipt are likely still present at the end of shelf-life. Despite these efforts, one nutrient is in constant decline – vitamins. Vitamins are ever-degrading and the degradation rate is influenced by a multitude of factors (Table 1). Vitamin losses can range from 15-80%, depending on the vitamin, form and time on the shelf. This vitamin degradation needs to be factored into the formulation to ensure that products meet desired nutrient targets at the end shelf-life, be it targets for maintenance or health claims.
|Vitamin Degradation Factors|
|Temperature||Oxidation Reduction Reactions|
Vitamins are essential to fuel metabolism and other metabolic systems of the body. They are found in almost all feed ingredients; however, the concentration within a particular feedstuff can be quite variable, depending on growing and harvest conditions, processing and particularly ingredient age. In addition, natural, unprotected vitamins are highly prone to degradation due to their chemical structure and interactions with their environment. This variability and low stability makes formulating nutritious diets using only natural vitamins extremely challenging.
Because of this, synthetic vitamins were developed to withstand the rigors of the supply chain. On average, synthetic vitamins have a 30% loss throughout the supply chain versus a 56% loss of natural sources. Synthetic vitamin compounds are either coated or chemically modified to protect them from the harsh supply chain that vitamin ingredients will endure. These modifications include protective coatings, such as the cross-linked beadlet for vitamin A; chemical structure modifications, such as with Vitamin C; and adding side-chains, such as thiamine mononitrate. These modifications help protect the vitamin from the numerous factors that degrade vitamins. Particularly in the processing steps, vitamins are subjected to moisture, heat, pressure and abrasion as the food is extruded and dried or canned.
Formulating for Vitamins
Vitamin degradation must be properly accounted for in the pet food formulation process. Improper degradation estimates can lead to detrimental health consequence and/or challenges with meeting the regulations set forth by the Association of American Feed Control Officials (AAFCO). Vitamin manufacturers extensively research the degradation of their products through various supply chain scenarios and establish degradation rate estimates for vitamins as a straight, in a premix, through processing, and while on the shelf. Using these values, one can back calculate and formulate a premix that accounts for this degradation.
To properly do this, a lot of information is needed to best predict the degradation. To start, the premix type and desired premix shelf-life affect the degradation rate, since select feed ingredients, such as trace minerals and choline chloride, accelerate the degradation rate. For processing losses, the preconditioning time, extrusion temperature and dryer temperature all need to be considered, since temperature, pressure, abrasion and moisture are all major vitamin degraders. Lastly, the finished product’s targeted shelf-life needs to be identified beforehand. A product sitting on the shelf for 18 months can lose ~45% of its vitamin potency from the time of packaging.
Vitamin premix over-formulation can be quite costly, but necessary to ensure a nutritionally adequate food. For example, using cross-linked vitamin A in an extruded dog food requires the dietary concentration to be almost six times the vitamin A target at the end of an 18-month shelf-life (Figure 1). Pet food manufacturers have pushed product shelf-life further and further in an effort to capitalize on production efficiencies; however, this results in an even greater initial vitamin fortification to account for the average 3% degradation per month for vitamins.
Combatting Vitamin Degradation
Unfortunately, little can be done to slow the degradation rate. A few options include controlling fat oxidation, which can oxidize vitamins, or enhanced packaging such as vacuum or nitrogen gas-flushed packaging to limit oxygen-vitamin interactions. The best method for addressing vitamin degradation is for pet food manufacturers to research their products and assess how they degrade over the course of the supply chain. Vitamin manufacturers and premix blenders have vitamin degradation estimates based on typical scenarios and these are great starting points for premix formulation. Pet food manufacturers researching and quantifying vitamin loss during premix storage, processing and their distribution channel enable formulators to accurately formulate premixes to account for all degradation over the course of the vitamin’s life and ensure the nutritional adequacy of their product.
Vitamins are important nutrients for nutritionally adequate pet food, but their constant degradation makes proper diet formulation challenging. Be sure you evaluate and understand how vitamins degrade over the course of your unique supply chain and work with a trained nutritionist to properly formulate your pet food diet for optimal vitamin success.