Currently the Pet Food Industry is looking for new nutrient sources with the goal of producing healthier and more complete diets for our four-legged friends, taking also into great account the sustainability. Years of research and development show now an outcome of novel protein and essential nutrient sources able to satisfy the necessities of pets and pet owners. Specially the rising interest in vegetarian and vegan diets has pushed the investigation towards the search of alternative ingredients such as novel vegetable and marine ingredients able to substitute traditional animal sources.1

But not only nutritional aspects are a challenge, also the stability towards oxidation is a key point to guarantee all nutrients arrive in perfect conditions to our pets. Then pet food is known for having very long shelf lives, up to 24 months or longer.2 

This article is focused on characteristics and oxidative stability of insect ingredients, marine ingredients, and their impact on the stability of finished pet food diets.

In this part no nutritional aspects of these ingredients will be considered; the discussion will concentrate on the oxidative stability of the different materials sharing relevant information based to the best of our knowledge.

STABILITY CONCERNS OF INSECT INGREDIENTS:

Nowadays the main sources of insect oils and meals are the black soldier fly (BSF), the mealworm, the grasshopper and the cricket. They are considered as good alternative protein sources. In general, and according to WHO they have amino acid levels meeting the standard requirements and fat is the second largest fraction.

Let’s see now some key data that are needed to evaluate the materials towards oxidation. Table 1 shows the fatty acid profile of black soldier fly larvae, showing that it is rich in saturated fat (58 % lauric acid being the largest fraction) and contains low levels of polyunsaturated fat. However, we can find in the market that the polyunsaturated fat content of BSF ingredients may have big variations among suppliers, from less than 1 to 15 %. At this point, it is known that these differences on the fatty acid composition of insect meals and oils from the same insect species may be due to the feeding. Indeed, it is possible to modulate the nutritional composition with the feeding the insects get. Thus, being possible to find insect ingredients which are high polyunsaturated and sensitive to oxidation, or which are more saturated and more stable.

By checking another insect species, for instance, cricket, we can see some significant differences in the fatty acid profile in comparison with the BSF. Especially higher amount of poly unsaturated fat which may make the stabilization of meal and oil from crickets challenging.

STABILITY CONCERNS OF NOVEL MARINE INGREDIENTS:

For the moment the sources available in the market are mainly from algae and small crustacean like Euphausia superba or Calanus fin. The main function of these ingredients is to substitute fish materials as alternative sources of ω-3 essential fatty acids (DHA, EPA). They may also bring extra advantages related to stability and nutrition but are still a very novel and higher cost ingredient than traditional fish materials.

Again, let’s see the identity card of these ingredients, their fatty acid composition. Table 2 presents the fatty acid profiles of one algae oil and two crustacean oils. They contain a considerable amount of polyunsaturated fatty acids thus EPA and DHA. This indicates that they are sensitive to oxidation and that antioxidants are needed to prolong their shelf life. If we compare the content of DHA and EPA of these novel ingredients with traditional fish oils like salmon and herring, we can see that indeed they are good alternatives.

PET FOOD DIETS CONTAINING NOVEL INGREDIENTS

When speaking about stability and oxidation risk of Pet Food Diets containing novel ingredients there are some aspects that we need to consider.

Usually, diets containing saturated fat, insect materials and no marine ingredients are, in general, considered as low risk for oxidation. This means that a traditional/standard stabilisation of the core and the coating of the kibble might be a good approach to reach the targeted shelf life.

Diets like the ones above but that are exported far away or/and that may contain one or two ingredients promoting oxidation like polyunsaturated fats or oils coming from marine materials will be classified as medium risk diets. For this type of diets we would suggest adding a higher amount of antioxidants. Especially if a sensitive polyunsaturated fat is used in the coating.

When we talk about high-risk diets, not impossible to stabilise but a bit more challenging, these would be diets with marine materials or containing high amounts of polyunsaturated fat or in fact low fat diets. Low fat diets, where not a lot of fat is applied on the coating of the kibble. Because we are relying on the antioxidants application on the surface and, the less fat on the surface, the less antioxidant protection. In such cases it is advisable to take a look into antioxidants application points very carefully and into all raw materials. If a high antioxidant sacrifice is detected, critical points need to be found and a strict control of all raw materials is needed.