Moisture plays a key role in the quality of pet food products. For each product, there’s an ideal range of water activity values that maximizes profit, nutrition, and tastiness while keeping the product safe from microbes and mold.
For example, a bag of dog food kibbles has a moisture sweet spot of 0.55-0.65. Any lower than 0.55, and the dog food is unappetizingly dry and hard. Not to mention the seller is losing money because the product has been over-processed. Any higher than 0.65, and the product will mold in the bag, becoming unacceptable.
Water activity has been used to guide the formulation of some of the most innovative–and commercially successful–pet food products. Complex pet food formulations like a simulated marrow-filled bone, a meaty cat food containing crunchy vitamin bits, and a shelf-stable, moist, meat-like product are all controlled by water activity.
Isotherms (curves showing how water activity changes as moisture increases and decreases in a specific product) are also a key formulation tool. They can be used to locate critical points where phase changes occur, to create mixing models, to investigate moisture-related issues, and in many other ways.
Know the moisture super-spec
Using water activity as a moisture super-spec can help you solve specific moisture challenges, determine shelf life, choose packaging, monitor incoming ingredients, prevent spoilage, and maintain taste, texture, and nutrition.
For example, there are a number of products on the market with multi-textured characteristics that use water activity. These products combine a hard, dry-baked pet food and a soft, moist pet food. The hard, dry component has the advantage of teeth cleaning, but is less palatable than a soft, moist food. Careful formulation using water activity keeps the crunchy kibble crunchy and the moist bits soft. The two can share a bag and a long shelf life without the kibble getting soft and the bits losing their moist texture.
Make every employee a moisture expert
Water activity is a test anyone can run to precise scientific standards. A certification course trains new users to measure water activity. In 20 minutes, nearly anyone can learn to run a reliable, repeatable, verified water activity test.