Expert Insights; a 3-Pronged Approach to Preventing Mould and Stabilizing Kibble

By Sarah-Jane Godfrey, Pet Technical Manager, Trouw Nutrition GB

In addition to achieving good palatability, optimal mouth feel, and overall quality, petfood manufacturers are responsible for protecting the safety and stability of our four-legged friends’ diets. Steps taken during the petfood manufacturing process can help support shelf-life stability and ensure product quality while defending against mould growth.

Petfood production involves extreme processes that make it challenging to maximise quality targets like tastiness, production efficiency, and nutritional value, while keeping the product free from moulds. Extrusion processing tends to aim for a low final moisture level in the finished kibble. Though this tends to control mould growth, it can come at the cost of extrusion efficiency and reduced profitability. Identifying and achieving the proper balance of moisture content, throughput, and quality can support safety and quality parameters without sacrificing production efficiency. Below, we consider a three-pronged approach to achieve a high-quality product, production efficiencies, and profitable economics.

1. Manage the moisture profile

During the extrusion and drying phases of production, kibble undergoes extreme thermal processes. A reduction in moisture content can adversely influence animals’ consumption preferences.

While compensating for moisture loss might sound as straightforward as adding more moisture, this action could increase the risk of mould developing and potentially reduce the final product’s shelf-life stability.

Managing the moisture profile of petfood considers both the moisture level and the water activity (aW) value. While aW and moisture content are related through the moisture sorption isotherm, they are not the same parameter. A high aW indicates the presence of free water that can support the growth of microorganisms including moulds. Various microorganisms also can feed on valuable nutrients, making them unavailable to the animal. Ingredients with high aW will affect ingredients with low aW and as moisture balances out throughout the feed, desired attributes such as texture, durability, and palatability can be compromised.

Within the food industry, aW is used to effectively manage moisture and preserve food. Similarly, in pet food production, aW is becoming a standard parameter to guide formulation and produce even safer and better-quality kibble.

As aW and temperature are the most significant factors detracting from quality and longevity on the shelf, determining the ideal aW range for a pet food can help manage both attributes. As Table 1 shows, varying pet food products among different product categories can have comparable aW levels but different moisture content.

To preserve palatability and reduce the risk of mould growth, an ideal aW range is between 0.55-0.65. Values below this range tend to result in dry and hard kibbles detracting from palatability. There is also an economic consideration since aW that is too low indicates the manufacturer is over-drying the product. Pet food is generally sold on a weight basis, so reducing a pet food’s aW content will lower kibble weight and ultimately producers’ profits. However, a higher aW value creates more favourable conditions for mould growth and fat oxidation, which can reduce shelf-life.

To address these conflicting conditions and bring a balanced approach to meeting petfood quality objectives, Selko, the feed additive brand of Trouw Nutrition, developed Fylax Petfood. The product offers a potent solution for optimizing the moisture profile of petfood while reducing the risk of mould growth. Containing a synergistic blend of organic acids, buffering agent, emulsifier, and phytochemicals, Fylax Petfood includes a thoughtfully selected surfactant that lowers the surface tension of water. This effect allows moisture to penetrate deeper within the food particles and supports more even moisture distribution within the product to help achieve quality targets (Figure 1).

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 (aW) Moisture content, %

0.744 17.0

0.618 0.501 9.3 7.1

0.615 0.652 0.560 9.2 9.4 7.4

0.407 6.4

0.364 0.506 0.461 0.450 0.541 5.3 7.4 6.3 6.0 7.2

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

Figure 1. Fylax Petfood supports even moisture distribution in commercial pet food production.

Figure2. ActiProp technology in Fylax Petfood shows a synergistic effect on mould inhibition.

2. Synergistically support safety, deter mould, and meet shelf-life requirements

As the commercial petfood market generally prefers a shelf life up to 24 months, assuring a product’s longevity and quality can pose challenges with regards to mould development.

Adding a mould inhibitor during preconditioning can help safeguard shelf life and defend against mould growth. ActiProp technology in Fylax Petfood effectively reduces mould growth while helping to maintain product quality and freshness (Figure 2). ActiProp increases the porosity of moulds’ cell walls, which allows its components to deploy a destabilising effect on the cell membrane. As this action allows better access for organic acids, the cell’s internal pH decreases, inhibiting growth and eventually killing the mould cell. Four key components delivered at the most effective quantities underlie this mode of action.

The mould inhibitors added during preconditioning must survive the extruder’s extreme environment. ActiProp® technology is designed to deter mould growth and is designed to deliver a sustained effect that can withstand commercial environments’ extended shelf-life requirements. Studies show that its active ingredient to deter mould growth is stable even at the high temperatures used in petfood production (Figure 3).

Figure 3. Propionic acid in Fylax Petfood remains stable at extrusion temperatures

3. Ensure efficacy with accurate dosing and application

Accurate dosing and application processes during petfood manufacturing are essential to a solution’s efficacy. Selko’s Feed Processing & Quality programme combines products and services with effective dosing solutions to support accurate, safe, and continuous product application during petfood production.

Dosing and application services are value-added components included in the programme and can be fully automated and integrated into feed production lines. A variety of systems are available to meet the nuances of customers’ production environments. Additionally, remote access capabilities support quick analysis to help guide dosing decisions and detect any necessary interventions.

A three-pronged approach can guide safe, palatable, and highquality pet food manufacturing supporting both pets and the economics of petfood production.

*The product mentioned in this article is not available in USA References available on request Contact: sarahjane.godfrey@trouwnutrition.com

Sarah–Jane Godfrey is a graduate from the University of Nottingham where she obtained a BSc in Agricultural and Food Sciences with specialization in Animal Science. She has over 20 years of experience working in the animal feed sector initially working as a pig and poultry nutritionist, latterly concentrating on her passion for companion animal nutrition. Sarah-Jane has worked for 14 years in the specialist premix sector and brings with her a variety of experience supporting customers in the European region on pet nutrition, premix design, regulation, market trends evaluation and new product development.