What’s in the (pre)mix?

If you make a cake from a mix that states ‘just add water, eggs and butter’, then that mix can be seen as a kind of premix: a multi-ingredient addition consisting of more than just flour.

Traditional pet food premix usually consists of more than 15 materials including vitamins, minerals and trace elements.

Choosing to add different forms of one material such as both inorganic and organic trace elements can increase the number of materials to 30 or more.

Nutritional essentials

Premixes are typically added to ‘complete’ rather than ‘complementary’ pet food as complete foods must meet all the daily nutritional requirements of cats and dogs, including vitamins and minerals.

The main pet food ingredients typically cover the major nutrients, including protein and fat. These main ingredients also contribute minor nutritional elements that are then considered in formulating the premix.

For example, liver-containing pet food may need lower vitamin A in the premix, fish inclusion may need removal of selenium, and insect-based formulations may see added taurine for cats.

Vitamin degradation

To achieve a particular level of a vitamin in the finished product, it is not sufficient to formulate to that level. Vitamins, both natural and synthetic, break down.

The main contributing factors to degradation are physical treatment and chemical reactions over time. Degradation of natural vitamins is typically more rapid and less predictable than for synthetic vitamins.

Extrusion and retort degrade vitamins: from less than 5% for the more stable forms to well over 50% for the least stable vitamins.

Process matters; thiamine (B1), for example, is degraded more by retort than extrusion. In their original packaging, manufactured synthetic vitamins have great stability.

In a mix, the materials react with each other, reducing stability. Choline chloride is the main cause of degradation due to its hygroscopic nature. Inorganic minerals and trace elements can be very reactive and greatly degrade vitamins.

Vitamins continue to degrade in the finished product after manufacturing due to exposure to oxygen, moisture and other components in the food.

This is one reason why it is hard to guarantee a longer shelf life for pet food, because degradation may have reduced vitamin levels to below minimum nutritional requirements.

Ensuring consistency throughout

Aside from the nutritional considerations, manufacturers are concerned with the physical characteristics of a premix.

One batch of premix may be divided across individual small packages that all need to deliver the expected nutritional profile. The ingredients therefore need to mix well before being packed off.

In the pet food factory, the bags may not be used in one go, but scoops may be weighed into the pet food. The nutrition at the top of the bag must therefore be similar to that at the bottom of the bag. Homogeneity of particle size plays a big role here.

For example, shaking a jar that contains both sugar cubes and loose sugar will bring the cubes (the larger particles) to the top. The same happens while handling bags of premix. This effect is particularly pronounced if the premix is transported in large tote bags.

Quick wins and opportunities

Nutritional wins can be made by preventing unnecessary degradation. Try to avoid adding the premix before the hammer mill. The heat and grind of the mill greatly reduce vitamin levels and waste value.

Removing choline chloride from the premix and dosing that separately helps maintain vitamin stability. Separating the premix into vitamins and minerals further helps to maintain this stability.

This changes the addition in the plant from 1 premix to 3 additions (vitamins, minerals and choline chloride) and requires recalculation to prevent overdosing or omitting nutrition.

Ask your premix manufacturer for support. Alongside essential nutrition, premixes also allow for additions of functional ingredients at levels too small to dose in the pet food directly.

This creates opportunities for adding globulins, lactoferrin or eggshell membrane. Slightly larger additions of chondroitin, glucosamine and inulin can be included in the premix and reduce the number of manual additions in the pet food plant.