With the majority of pet owners feed our pets commercially prepared pet foods I am often being asked: “When choosing a pet food what type of food should I feed? Dry, semi moist, or canned?” We have countless choices these days, all of which are claiming to be the best one for your pet. This in itself can make choosing the best pet food a very confusing endeavor. When answering these questions I found it is helpful if one understands how pet food is actually made. Because this knowledge by itself may make it a little easier to choose the type of food to use. Though it is not the only and most important question to be considered when choosing the best possible food. Pet owners see usually two things. There is the beginning, in our minds a farm in which wholesome, healthy pet food ingredients originate. And there is the end, a beautiful bag in the store shelves, showing us again pictures of a so perfect world of pet food ingredients. What we don’t see is the, what many call “dangerous middle”, the processing, or as Dr. Wysong, D.V.M. calls it “food torturing” and the processing degradations.
The bulk of pet food available in today’s market is dry food. There are several types of manufacturing that lead to dry food. They include baking, pelleting and extrusion. The manufacturing process is similar for all of them except for the final pressing and cooking process. I decided to discuss the most commonly available type: Extrusion. While there are as many variations in the processing and manufacturing of dry pet foods as there are pet food manufacturers making them, I will explain the basic manufacturing process which is typically followed by most of them.
Obviously, the manufacturing of pet food begins with assembling the raw materials. Most raw materials are grain, meat and fat that arrive in train cars or semi trucks in loads weighing between 10,000 and 40,000 pounds. Concentrated vitamins and minerals typically arrive in 25 to 50 pound bags. After arrival these raw materials are stored in appropriate holding areas. Most grains being held in silos.
The raw materials are then ground to the correct particle size. Grinding increases the availability of nutrients. It also improves the ease in which they are processed. Commercial hammer mills are often used to grind the particles to the proper size. Most dry mixes are ground to a consistency of coarse flour. A uniform size is very important for proper water absorption and cooking.
The next step is proper mixing of all the ingredients, which is very important to create a consistent product. If the mix is not thoroughly blended, essential nutrients could be excessive or absent in individual pieces of the finished product. Large ribbon blenders are used to mix batches of up to 2,000 pounds at a time. At this initial mixing, only the dry ingredients are included. Then the dry mix is stored until the next step can be completed.
The extrusion process is very similar to the process of bread making: Mixing, kneading, proofing or rising, shaping, rising again, and slicing. The dry mix is first preconditioned to start the gelatinization of the starches. A pre-conditioner measures accurately the amount of the dry mix and blends it with the measured liquid portion that can include fat, meat products, additional water, and steam. This wet mix stays in the pre-conditioner for about 45 seconds. While in the pre- conditioner, the starch is cooked about 25%. The preconditioned food is then moved into an extruder. Extruders were originally designed for the plastics industry, but are now used by 90% of pet food manufacturers. The extruder consists of a cylindrical multi segmented barrel with a screw that propels, mixes, and further cooks the material, and then forces it through a die. There it is cut to the desired length by a knife. The product moving through the extruder produces its own friction and heat, which then cooks the mix. The speed and friction levels can be varied depending on the formula, to ensure that the product is cooked at the right temperature for the right length of time.
The newly formed kibbles, still being soft and spongy, are then transferred from the extruder to the dryer. Here additional moisture is removed. Most kibble takes about 15 minutes to dry properly. If kibble is dried too quickly or at too high of a temperature, it will be more fragile and will break during handling. This actually creates a high level of so called fines. Fines are very small particles of food, which often settle to the bottom of the bag.
The kibble then goes through a cooling process of around 7 minutes. If the kibble is too hot when it leaves the dryer and is packaged before it cools, condensation will develop, which will encourage the growth of mold or bacteria.
Enrobing is the last step in the manufacture of dry pet foods, and entails the addition of either liquids or powders to the outer surface of the kibble. Fat and flavor enhancers are usually added at this stage. Fat is not usually added during the mixing stage because it would disrupt the starch gelatinization. Fat and flavor enhancers greatly improve taste and palatability, and are most effective when applied to the outside of the kibble.
Pretty impressive, isn’t it? Now let’s come back to what I said in the beginning. There is the start. We see a farm, golden corn, oats and juicy, fresh chicken and other animals. At the end we are being told that exactly those ingredients are in our bag of pet food we just bought. Not just that, but now it is even 100% complete, all natural and scientifically tested. To prove it we are presented colorful charts and platinum, gold and silver certification seals and awards. If we spend a little more money we even get one which is endorsed by some Hollywood celebrity, possibly even made by one. But we are not being told the entire story here. During the manufacturing process, while drying, scoring, milling, heating, baking, dehydration, extruding, freezing and refining the wholesome ingredients the following took place: There were additions made. Such as artificial colors, flavors, texture, preservatives and chemicals. And then there are the processing degradations. Examples: Wheat. Whole wheat contains many minerals, vitamins, enzymes, proteins, fats and carbohydrates. Ground whole wheat retains many of those nutrients. Fractioned wheat, i.e. white wheat flour, as being used in mass produced dry pet food does no longer contain these nutrients. Therefore it has to be fortified to get those nutrients back into it. Often this is done by adding chemicals or synthesized substances. Or take rice. Whole rice contains dozens of important nutrients. However, during processing as described above, those nutrients are being lost and the rice ends up primarily being starch. Once whole rice is fractioned into white rice, unbalanced nutrition is created. This is setting a perfect stage for disease.
The bottom line is that once ingredients are being processed, they become something opposite and completely different from the wholesome starting material. The list of degradations taking place during processing of ingredients in the dry food manufacturing process is as impressive as the manufacturing process itself. Unfortunately to me it is a negative impression. Sure, packaged products must be processed. And if it is just for the sake of digestibility and shelve life. However, there are better, gentler processing methods out there. Those however are apparently only known to manufacturers who realize, as Dr. Wysong says, “that food processing is more than a mere business. It is an opportunity to do great by preventing disease and optimizing health.”
To complete my story, in Part 2 I will discuss in more detail the degradation and also take a look at the manufacturing processes for wet food. Stay tuned.