Corn Oil: Green Or Polluting?

Corn oil is a vegetable oil, and vegetable oils are regulated under 40 CFR 112, which has identical requirements for petroleum and non-petroleum oils. Vegetable oil spills are uncommon but can cause the death of animals through suffocation, oxygen depletion, and other toxic effects. Vegetable oils are also linked to deforestation, species loss, and high greenhouse gas emissions. Corn oil recovery and conversion to biodiesel have been widely adopted at corn ethanol plants, and the US EPA projected 2.6 billion liters of biodiesel will be produced from corn oil in 2022. Corn-based ethanol is likely a bigger contributor to global warming than gasoline due to emissions from land use changes, processing, and combustion.

Corn oil's production process

Corn oil is derived from the germ of corn kernels, constituting about half of the kernel. The process of extracting corn oil from corn is complex and extensive, and it involves several steps:

Firstly, the corn kernels are mechanically pressed to separate the oil. This can be done using a hydraulic or screw press. The pressed cake, also known as the corn germ, is then dried in a kiln. The oil is further extracted by washing it with a solvent, typically hexane, which is a chemical that causes the release of oil. Hexane has been associated with negative impacts on the nervous system in humans and animals. The dissolved oil is then recovered by evaporating the solvent, leaving behind pure corn oil.

Following this, the oil undergoes a series of chemical processes to remove impurities and undesirable smells and tastes. This includes deodorization, where undesirable odours and flavours are removed, along with some beneficial compounds. Winterization is another process, where waxes and saturated fats are eliminated so that the oil remains in a liquid state at low temperatures.

These processes result in the removal of many vitamins and minerals, and potentially harmful substances may be introduced. Corn oil is considered a refined oil due to the extensive procedures it undergoes before being sold commercially. The final product is widely used for cooking, especially deep frying, because of its high smoke point, neutral taste, and light colour.

Health effects of corn oil

Corn oil is a refined vegetable oil widely used for cooking, especially deep frying, thanks to its high smoke point of approximately 450°F (232°C). It is also used for industrial purposes and as an ingredient in cosmetics.

Corn oil is 100% fat, containing no protein or carbohydrates. It is composed of polyunsaturated omega-6 fats, monounsaturated fats, and saturated fats. It also contains vitamin E, an important antioxidant that can help protect the body from free radical damage. Antioxidants are compounds that neutralise molecules called free radicals, which can increase the risk of conditions like heart disease, type 2 diabetes, and some cancers. Vitamin E also plays a role in supporting immune function, eye health, skin health, and cardiovascular function.

Corn oil is very high in polyunsaturated fats, especially linoleic acid, which makes up about 30%–60% of corn oil. Linoleic acid can be beneficial when consumed in small amounts and in a healthy ratio to other types of fats. Once eaten, linoleic acid is converted to gamma-linolenic acid (GLA), which has been found to help reduce inflammation and keep cholesterol levels within a healthy range. GLA may also help decrease the risk of developing dangerous blood clots and may offer some protection against insulin resistance.

Corn oil also contains phytosterols, plant-based compounds that can help reduce LDL ("bad") cholesterol by blocking its absorption and supporting healthy levels of total cholesterol. Phytosterols are also potentially anti-inflammatory, and eating a diet rich in anti-inflammatory foods may decrease the risk of certain conditions, such as heart disease, type 2 diabetes, and some cancers.

However, corn oil is highly refined and the process of extracting it from corn can remove many vitamins and minerals, as well as introduce harmful substances. For example, corn is often washed with a solution containing hexane, a chemical that has been shown to negatively impact the nervous system in humans and animals.

Overall, while corn oil does have some potential health benefits, these may be outweighed by its negative effects, particularly its high level of inflammatory omega-6 fats. Healthier alternatives for cooking include olive oil or coconut oil.

Corn oil's industrial applications

Corn oil is a refined vegetable oil that is widely used in cooking, especially for deep frying. It is derived from the germ of corn, which is the part of the corn that germinates and grows into new corn. Corn oil is composed of 99% triacylglycerols, with polyunsaturated fatty acids (PUFA) making up 59% of the oil, monounsaturated fatty acids making up 24%, and saturated fatty acids (SFA) making up 13%.

Corn oil has a variety of industrial applications. It is used as a feedstock for biodiesel, as well as in the production of soap, salve, paint, erasers, rustproofing for metal surfaces, inks, textiles, nitroglycerin, and insecticides. Corn oil is also used as an industrial cleaner and lubricant, and in the cosmetic industry as an ingredient in cosmetic products, liquid soaps, shampoos, and margarines. Additionally, corn oil is sometimes used as a carrier for drug molecules in pharmaceutical preparations.

The process of extracting corn oil from corn involves mechanical pressing of the kernels to separate the oil, followed by a series of chemical processes to remove impurities and undesirable smells and tastes. Solvent extraction using hexane or 2-methylpentane (isohexane) is commonly employed, with the solvent being evaporated, recovered, and reused. The subsequent steps of refining include degumming, alkali treatment, winterization (removal of waxes), and deodorization. These processes enhance the taste, smell, and appearance of the corn oil, making it suitable for a wide range of industrial applications.

Corn oil is a versatile product with a range of industrial uses, contributing to its popularity in various sectors beyond the culinary realm.

Corn oil's environmental impact

Corn oil is a refined vegetable oil widely used in cooking, especially for deep frying. It is also used in cosmetics, biodiesel production, and animal feed. The process of extracting corn oil from corn involves mechanical pressing and chemical processes to remove impurities, undesirable smells, and tastes. This process removes vitamins and minerals and may introduce harmful substances. For example, hexane, a chemical used to release oil from corn, has been linked to negative impacts on the nervous system.

The environmental impact of corn oil is primarily related to its production and use. Corn oil production requires large amounts of corn, which demands significant agricultural resources, including land, water, and pesticides. The refining process also consumes energy and generates waste. Additionally, corn oil is often used as a frying oil, contributing to waste oil disposal issues if not properly recycled. Improper disposal of waste cooking oil can pollute water bodies and contribute to fatbergs in sewage systems.

The use of corn oil in biodiesel production offers an alternative fuel source, which can help reduce dependence on fossil fuels and their associated environmental impacts. However, the overall environmental impact of corn oil biodiesel depends on various factors, including the energy and resources required to grow corn, the efficiency of the conversion process, and the emissions generated during fuel use.

While corn oil provides some nutritional benefits, such as vitamin E and linoleic acid, it is primarily composed of fat, with no protein or carbohydrates. The high levels of omega-6 fatty acids in corn oil can lead to an imbalance in the diet, resulting in potential health issues such as inflammation, insulin resistance, and increased risk of cardiometabolic diseases. The refining process of corn oil can also introduce potential carcinogenic contaminants.

Overall, the environmental impact of corn oil is influenced by its production, use, and disposal. While it has some industrial applications, the health concerns associated with its consumption and the potential environmental impacts of its production and disposal should be carefully considered.

Healthier alternatives to corn oil

Corn oil is widely used in cooking, especially for deep frying, due to its high smoke point. It is also used for industrial purposes and in cosmetics. However, it goes through an extensive refining process to be extracted from corn, which removes many vitamins and minerals. While corn oil does contain vitamin E and beneficial fats, it is mostly pure fat and does not provide significant amounts of fibre, protein, antioxidants, or minerals.

• Canola oil: This oil is similar in flavour and thickness to corn oil and can be used as a replacement in cakes, cookies, and other baked goods. It has the same calories and nutritional value as corn oil.
• Peanut oil: Peanut oil can be used as a substitute for corn oil in baking recipes and has the same calories and nutritional profile as corn oil.
• Safflower oil: Safflower oil is flavourful and can be used as a substitute for corn oil in most recipes. It is, however, pricier than other options.
• Olive oil: Olive oil has a stronger taste than corn oil, so it is recommended to use an extra light variation when substituting it in cooking or savoury sauces. It is not suitable for baking.
• Grapeseed oil: One of the healthiest alternatives, grapeseed oil is low in fat and has a light flavour, making it a good substitute in salads and dressings.
• Soybean oil: Soybean oil can be used as a replacement for corn oil when cooking. However, it has a slightly higher level of saturated fat, so it may not be the best option if you are trying to reduce your saturated fat intake.

It is important to note that while these oils can be used as substitutes for corn oil, a qualified healthcare professional should be consulted for specific dietary advice.

Frequently asked questions