According to a paper published in the Journal of Nutritional Sciences in 2014, based on surveys conducted in Germany and France, a majority of pet parents feed their dogs commercially produced foods, and that between one-third and one-half of people surveyed feed this type of food exclusively (5). Commercially produced foods provide a number of benefits including, a pre-balanced diet, easy storage, and a generally lower price point (5). These dry processed foods can also be tailored to your dog’s specific stage of life or health conditions. For example, my pup has a sensitive stomach and skin, so we found a specifically formulated food to help with these conditions (Purina Pro Plan for Sensitive Skin and Stomach).
Extrusion cooking is a very common way to process dry pet foods, such as kibbles. According to a study in 2006, 95% of dry pet foods are extruded. There are many known benefits of extrusion, which explains how widespread this method is. Some of these benefits include the detoxification, sterilization, and texturization of a variety of ingredients. This makes it much easier to feed pets a balanced diet (2). Dry foods that have been extruded don’t need to be refrigerated, which allows for easy storage of large quantities of pet foods
An extruder machine consists of a funnel that feeds raw materials into a barrel. Within this barrel, there are screws that rotate and push the material through the barrel and towards the die at the opposite end. The die shapes the product. This energy from the barrels emits heat through friction and towards the end of the barrel near the die, with immense pressure (3). The number of dies in an extruder depends on the complexity of the shape of the desired product. There is often a knife (not pictured in the below figure but would sit just outside the die) that slices off desired shapes. The blades can be adjusted for the type of cut. Food extruders use high temperatures over a short period of time. This makes them particularly useful for pet food processing, as it prevents the denaturation of important compounds such as proteins, amino acids, vitamins, starches, and enzymes (4). Denaturation is the breakage of certain weak linkages. Once compounds are denatured, this process cannot be undone.
![](https://wp.wwu.edu/lowerfoodandchemproj/files/2021/11/Labeled-Extruder-Figure-1024x444.jpg)
Image Description: A long blue rectangle with a black box on the right end (box is labeled b). The box is connected to a rod (rod is labeled e) that extended through the center of the long rectangle. There are screws at different angles connected to the rod. The angles vary depending on what cooking zone it is in. The zones are labeled h,g,f,d (from left to right). Attached to the left end of the rectangle across from the box is a trapezoid (labeled i). On the top of the right side of the rectangle, there is a funnel (labeled a). To the left of the funnel is a pipe with a right angle also facing towards the left (labeled c). There is a white border around the long blue box (the border is labeled j).
Original Image inspired by: Oonsivilai, Anant & Oonsivilai, Ratchadaporn. (2008). Parameter estimation of frequency response twin-screw food extrusion process using genetic algorithms. WSEAS TRANSACTIONS on SYSTEMS. 7. 1207-1217.
- Munoz SS. Amid the recall of dozens of brands of pet foods, many dog and cat owners are grappling with a tough question: “What can they safely feed their pets?”. New York, New York: Wall Street Journal; 2007. p. D7.
- Tran, Q.D., Hendriks, W.H. and van der Poel, A.F. (2008), Effects of extrusion processing on nutrients in dry pet food. J. Sci. Food Agric., 88: 1487-1493. https://doi.org/10.1002/jsfa.3247
- Oonsivilai, Anant & Oonsivilai, Ratchadaporn. (2008). Parameter estimation of frequency response twin-screw food extrusion process using genetic algorithms. WSEAS TRANSACTIONS on SYSTEMS. 7. 1207-1217.
- Moscicki, Leszek & Zuilichem, Dick. (2011). Extrusion-Cooking and Related Technique. (10.1002/9783527634088.ch1.)
- Daumas, C., Paragon, B. M., Thorin, C., Martin, L., Dumon, H., Ninet, S., & Nguyen, P. (2014). Evaluation of eight commercial dog diets. Journal of nutritional science, 3, e63. https://doi.org/10.1017/jns.2014.65