balances out throughout the feed, it can potentially affect attributes such as texture, durability, and palatability. Water activity, alongside temperature, is the most important determining factor for the degree of quality loss and shelf life can be optimised by determining the ideal water activity range for a pet food. Like the food industry, in pet food pro- duction, water activity is becoming a standard parameter to guide formulation and produce safer and more high-quality kibble. Table 1 shows that different pet food products from different segments can have comparable water activity levels but different moisture content. The ideal water activity range is between 0.55-0.65 to maintain palatability as well as reduce the risk of mould growth. Any lower may result in dry and hard kibbles which negatively impacts palatability. Getting an aW too low fur- thermore impacts the economic benefit as the manufacturer is over-drying the product. As pet food is generally sold on a weight basis, reducing the moisture content will result in a lower weight of the kibble and in the end missed profit. On the contrary, a higher aW value increases the risk of microbial growth such as moulds as well as fat oxidation which reduces the shelf-life of pet food. Selko, the feed additive brand of Trouw Nutrition, developed Fylax Petfood, a potent solution that supports moisture profile optimisation while reducing the risk of mould growth. Surfactants in the feed supplement lower the surface tension of water, thus facilitating deeper moisture penetration within the food particles. This supports an even moisture distribution within the product and helps to achieve quality targets (Figure 1).


2


Synergistically supporting safety and a mould free shelf life To be commercially interesting, petfood is gen- erally produced with a shelf life up to 24 months.


Assuring petfood longevity and quality can pose challenges with regards to mould development. A mould inhibitor can be added during preconditioning to help assure a mould- free shelf life. Fylax Petfood contains ActiProp technology to effectively reduce mould growth and helps to maintain the quality and freshness of pet food (Figure 2). This technology increases the porosity of moulds’ cell walls, allowing its com- ponents to exert a destabilising effect on the cell membrane. As this effect supports better accessibility of organic acids, the cell’s internal pH decreases, inhibiting its growth and eventually killing the mould cell. This mode of action is driven by the synergy of four key components delivered at the most effective quantities. Mould inhibitors that are added during preconditioning need to withstand the extreme environment of the extruder. The technology is designed to achieve a prolonged effect that can stand up to the extended shelf-life requirements of commercial environments. Studies show that the active ingredient to impact mould growth remains stable at high temperatures that occur during extrusion.


Figure 2 – ActiProp technology in Fylax Petfood shows a synergistic effect on mould inhibition.


45.0 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0


40.7 32.5 21.0 16.9 10.9


Buffered Propionic Acid


Aspergillus chevalleri 3


4.1 2.5 Emulsifier


Phytochemical 13.4


Additive Effect (Theoretical)


Penicillium lanosocoeruleum


Effective application is essential Even the most sophisticated petfood production technologies will not deliver the desired results if the mechanisms for dosing or application are not


aligned with the production environment. This is why Selko has developed its feed processing and quality programme that combines products and services with effective dos- ing solutions that allow for accurate, safe, and continuous application of products during petfood production. This complementary service within the programme can be fully automated and integrated within the feed production lines. Various systems are available, depending on the needs, and allow for automated adjustment of inclusion rates. Remote access capabilities support quick analysis and help guide de- cisions. Managing moisture, mould and dosing mechanisms delivers a precision approach to achieving effective, efficient, and economical pet food production.


*The product mentioned in this article is not available in the USA References available upon request


Table 1 – Selko Water Activity and moisture survey of commercial types of pet food ranging from economy to premium brands.


Commercial pet food


Semi Moist Dog Food – Beef, carrots and grains Dry Kibble Dog Food – Adult regular Extra Dry Kibble Dog Food – Adult small breeds Dry Kibble Dog Food – Adult medium breeds Dry Kibble Dog Food – Puppy


Dry Kibble Dog Food – Puppy sensitive Dry Kibble Cat Food – Adult economy Dry Kibble Cat Food – Supermarket brand Dry Kibble Cat Food – Adult cats Dry Kibble Cat Food – Premium adult Dry Kibble Cat Food – Premium kitten Dry Kibble Cat Food – Cat adult


Water Activity 0.744 0.618 0.501 0.615 0.652 0.560 0.407 0.364 0.506 0.461 0.450 0.541


▶ ALL ABOUT FEED | Volume 30, No. 3, 2022


Moisture content, % 17.0 9.3 7.1 9.2 9.4 7.4 6.4 5.3 7.4 6.3 6.0 7.2


21


ActiProp


Percentage of fungal cells stained


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