No Option But To Properly Cool Extruded Products


“Why do I need to cool extruded products?”  The answer is simple; it controls the water activity, product quality and nutrient value; all important aspects in producing a high quality product. So, what is water activity? Water activity is the most critical factor in determining the quality and safety in the feed or food that you manufacture. It is defined as the amount of bound or available water in the product. Its range is from 0-1. The closer the activity to 1, the more available the water activity is and the more likely that mold, yeast and bacteria will grow causing spoilage.

Water activity also affects the shelf life, texture, flavor, and smell of foods. Temperature, pH and several other factors influence if and how fast organisms will grow in a product; water activity may be the most important factor in preventing or promoting spoilage. Most bacteria, for example, do not grow at water activities below 0.91 and most molds cease to grow at water activities below 0.80.  By measuring water activity, you can predict which microorganisms will and will not be potential sources of spoilage. Water activity–not water content–determines the lower limit of available water for microbial growth. High water activity occurs in products when it has not been properly cooling before bagging or storing in a bin.

Products stored in a bulk bin without prior cooling, will result in the condensation of the products moisture on the wall of the bin or container while the product slowly cools; thus increasing the available water ( high water activity). This will result in the growth of mold and bacteria especially in the presence of highly available nutrients resulted from the extrusion process.  Products will also trap heat and moisture resulting in the degradation of the nutrients. Certain products also require drying followed by cooling; as is the case in extruded pet food, aquatic feed, textured soy protein or, high moisture by products.  The drying process may require added heat to decrease moisture content to less than 10% after proper cooling; this controls the water activity and is the key top extended shelf life and quality of the product.

When extruding or extruding/expelling high oil ingredients such as whole soybeans, cottonseed, rice bran, canola and other high oilseeds; not cooling the product properly can result in spontaneous combustion. If not properly cooled, liberated oil in the extruded or expelled product acts as fuel in the presence of trapped heat in the pile and can cause spontaneous combustion. There is also evidence from our own experience with soybeans that lack of cooling the extruded beans or the ExPress soybean meal may result into reversing the activity of the anti-nutritional factors.

Bottom line, a properly cooled extruded product is not an option. It is a requirement. Our nutritional, service and sales team are dedicated to providing you exceptional support and nutritional advice.  We can provide you with technical guidance and business consultation services to help you produce a high quality product.

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