The role of emulsifiers and stabilizers in wet pet food

Emulsifiers and stabilizers are commonly used ingredients in liquid products. These are added in small quantities and modify the oil and water fractions of a product to reach the desired consistency and maintain it throughout the product’s shelf life. Emulsifiers allow 2 liquids to blend that would not normally mix, such as oil and water. Stabilizers give structure to products by binding, holding or thickening the water fraction.

Examples in human food

These ingredients are added to wet pet food to create chunks, viscous gravy or jelly. Rummaging through my kitchen cupboard, I can also readily find some examples in human food products: corn starch for thickening and controlling the flow of tomato ketchup, xanthan gum as a stabilizer in mayonnaise and animal- derived gelatin to form the gel capsule around a supplement.

Some ingredients have multiple functions, while others have only one. In some instances, several materials must be combined for the desired effect. For example, my vegan algae oil capsules are not encapsulated with gelatin but instead use a combination of modified starch, glycerol, carrageenan and sodium carbonate. Suppliers of hydrocolloids and gelling agents have the expertise required to create the desired effect in the final product.

Gelling

Carrageenan (additive number E 407) is a gelling agent, and the gel strength and viscosity depend largely on its type (kappa is often used). While carrageenan does not have a legal maximum quantity for pet food, cassia gum as a gelling agent (1f499) does. Therefore, it must be declared on the label in the ‘additives’ section, together with the level of inclusion. Further requirements of cassia gum are that it is food grade, used in complete pet food with a moisture content of over 20% and combined with carrageenan at an inclusion of at least 25% of the cassia inclusion.

Thickening

Commonly used thickening agents include plant- derived polysaccharide hydrocolloids, such as guar gum, xanthan gum and sodium alginate. These ingredients react with water, thereby affecting the texture of the finished product. They can have more potent effects in combination with other ingredients.

Emulsifiers

Some stabilizers also have emulsifying properties. Lecithin is an emulsifier that can be used in pet food. It can be derived from soy or sunflower – which is a consideration for manufacturers concerned with customer perception.

Synergistic effects

Carrageenan forms an elastic gel in the presence of potassium ions, whereas calcium and sodium lead to a harder but more brittle gel. Carrageenan gel becomes more elastic, looser and stickier when combined with xanthan gum, and it is more stable after production. 

The otherwise modest sodium alginates can form heat- resistant gels when combined with calcium lactate.

Other considerations

Gelatin is used in human foods such as gelatin pudding. It is a protein-based product that denatures when heated at high temperatures, but it is suitable for cold applications. Gelatin is derived from pig bones and skin, which makes it unsuitable for kosher, vegetarian and vegan recipes. The ingredient does not, therefore, lend itself to plant-based formulation. Seaweed-derived carrageenan qualifies as a more suitable candidate in this instance, but it would require the appropriate addition of other ingredients to reach the desired functionality in either cold or hot applications.

Clean label

Starches can be used for their gelling, thickening and stabilizing properties. Rice, potato, oat and tapioca starch can sometimes be used in place of guar/ xanthan gums. The functionality greatly depends on whether they have been precooked (gelatinized). Treatment with chemical, physical and/or enzymatic methods can be used to create ‘modified starches’, which have a more enhanced and sustained functionality throughout the lifespan of the finished product.

Apple fiber and citrus fiber have high pectin and fiber content and can provide a clean-label solution for thickening or emulsifying. Their properties depend on how the material has been treated for it to have the desired functionality, so referencing functionality with the manufacturer is recommended.

Spray-dried plasma is a feed material, as opposed to an additive, with both gelling and emulsifying characteristics. As a by-product of meat production, the high protein content of blood plasma can boost the protein content of pet food in a relatively sustainable way. Furthermore, research over the past decade has shown positive impacts on the immune system and nutrient digestibility in pets.