Canola meal, soybean meal, sesame meal, flax seed meal. What do these products have in common? They are all byproducts from oil seed processing. An oil seed is grown for its oil. For example, canola seed is 45% oil; soybeans are 18% oil; sesame seeds are 48% oil; flax seeds are 34% oil. Due to the amount of oil, a whole seed is not always a good protein source in livestock feed; however, if we remove a portion of the oil, we have a high protein meal that works great in feeds.
There are 2 main ways to extract oil from an oil seed. One method is expeller pressing, which uses mechanical force to press the oil out. The other, more common method is solvent extraction, which uses a hexane solvent to remove the oil.
Roughly 99% of the soybean meal produced in the United States is solvent extracted due to its effectiveness in removing oil from the seed. For example, soybeans are 18% oil. After the solvent extraction process, there is only 1.5% oil within the soybean meal. The first step is a three-part process of cracking, heating, and flaking. During the second step, flakes go through an expander, which heats the oil seed using steam, creating a porous product making oil extraction easier. The final step for removing the oil is adding a solvent like hexane, ethanol, or a mixture of the two that removes the oil. The solvent itself is then removed from the oil (Soybean Meal | Feedipedia, n.d.).
In the expeller press process, mechanical force is used to remove the oil. Resaca Sun Products has an oil processing facility with an expeller press. Our first step is to clean the seed of any debris, non-seed plant material, and immature seeds. Once the seed is cleaned, it’s conditioned where the seed is heated in a steam jacketed vessel. Conditioning helps with the oil extraction process. The temperature needs to be precise during the expeller process. If soybeans are not heated enough, the trypsin inhibitors in soybeans cannot break down properly. If soybeans get too hot, the protein digestibility decreases. The conditioned seed is then sent through the first press where, which is the expander/extruder. This process removes about 50% of the oil. The next step is the expeller, which is the second press. This removes more oil. The meal is then cooled and ground to a consistent texture. Oil is then filtered and degummed. The Expeller Pressed method is the chemical free way of removing oil from oilseeds
After oil seeds are processed, we are left with a high protein meal and oil. As mentioned before, solvent extraction is the most effective method of removing oil from an oil seed. The table below shows a comparison of solvent extracted meals compared to expeller press meals. Resaca Sun Feeds uses protein meals from Resaca Sun Products, which produces expeller pressed meals.
*Values are from Resaca Sun Products’ meals
All other values from “Ingredient Analysis Table: 2011 Edition”
Oil extraction results in two products: oil and high protein meal. The oil may be used in a variety of ways such as in the human food industry, the animal feed industry and as renewable energy sources. Further processing is required when using oil for human food or renewable energy. High protein meals are often used in animal feeds. Some feed tags will specify if the soybean meal, canola meal, or other meals are either expeller pressed, or solvent extracted. A feed tag will contain the wording, “Soybean Meal (Expeller)” or “Canola Meal (Expeller Pressed),” which indicates how the meal was produced. As a nutritionist, I prefer formulating diets with expeller pressed soybean meal because it is higher in energy, making it easier to produce feeds that meet the energy and fat requirements of livestock. Expeller Press is also a better protein source for ruminants as there is more bypass protein for the cow, sheep, and goats to utilize. Expeller Press is a more natural way to remove the oil from an oilseed, making it the perfect fit for our non-GMO feed principles.
Canola meal, soybean meal, sesame meal, and flax seed meal are all valuable byproducts of oil seed processing. Oil extraction can be achieved using two main methods: expeller pressing and solvent extraction. While solvent extraction is more efficient in removing oil, resulting in higher protein meals, expeller pressing offers a chemical-free option which offers more energy and is preferable in non-GMO feeds. Both methods produce oil that can be used in different industries, including food, animal feed, and renewable energy. Ultimately, the choice between expeller pressed and solvent extracted meals depends on specific nutritional requirements and feed formulation principles.
Soybean meal | Feedipedia. (n.d.). https://www.feedipedia.org/node/674