ISSUE FOCUS FEED & ADDITIVE MAGAZINE April 2024 27 that address them effectively. Our expertise in microbial risk management in feed and feed ingredients makes us well-equipped to support stakeholders in overcoming these obstacles and contributing to the health and well-being of livestock. Selko’s raw material quality programme focuses on three pillars, namely Analysis, Technical application, and Management. This allows us to identify risks in a timely fashion and proactively control these risks. ANALYSIS Gram negative bacteria like Salmonella can stay dormant for several years, while they await the correct environment to grow. They thrive in an optimal temperature of 37°C however they can also survive at very low temperatures and in a varying pH of between 4-9. Salmonella is nearly impossible to eliminate, therefore, it needs to be controlled before it goes into the multiplication phase and exponential growth takes place. Any raw material that has gone through processing tends to have a higher risk for Salmonella contamination due to free water being present. This free water provides the perfect environment for bacteria to grow. Combine that with the optimal temperature and you will have exponential growth. In addition to gram-negative bacteria, the challenge of mould is also very prevalent in grains. Mould growth can occur in the field before harvest, increasing the risk as it is put into storage. Higher moisture levels coupled with inadequate storage facilities can pose a big problem and cause a lot of spoilage quantitatively but also qualitatively. Mycotoxins, a secondary metabolite of moulds, can further degrade the quality and safety of stored grains. Hence, effective mould control can help to prevent rising mycotoxin levels. Early detection of microbial risk can guide procedures and inform tailor-made solutions to address specific needs, depending on the local situation and conditions. A good sampling plan is crucial to establish the microbial risk and how to best mitigate those risks. By taking samples across the process at critical control points (CCP’s) and analysing them for microbiological load, challenges can be identified. CCP’s are specific places along the production process where there could be a high risk for microbial contamination. The first one being the raw material intake pit. Different kinds of raw materials from different sources and quality levels enter the feed process. Cross contamination can easily occur during this step, so it is very important to monitor this closely. As condensation is a major risk factor, due to the rapid increase of free water, any place where this occurs is a CCP. Usually, condensation occurs when hot material undergoes a sudden drop in temperature. Such thermal conditions can occur when feed leaves the pelletizer, when feed or feed ingredients move through the drying stage, and inside coolers at a feed mill or at oilseed crushers after the DT/DC (heating and cooling step in the oilseed crushing process). Furthermore, locations that are difficult to clean could harbour biofilm, which is a slimy layer formed by microorganisms like bacteria and fungi providing them protection and enabling them to thrive on surfaces. Examples of this could be a dead-end at a screw conveyor, bucket elevators, or even mixers that are sometimes neglected because of continuous production. Common sense tends to be key when identifying CCPs in the plant. Seeing and feeling where the condensation might occur, and smelling can help
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