Corn oil is an industrial seed oil that’s made from the seed (or kernel) of corn.
Like the vegetable (or grain, depending on when it’s harvested), corn oil has a golden yellow hue. Some say corn oil has a slight buttery flavor, but for the most part, it’s very neutral. This makes it a popular choice in packaged and processed goods.
There’s a lot of processing involved to make corn oil. Typically, the oil is mechanically and/or chemically extracted and then refined (e.g. using a solvent like hexane), according to holistic registered dietitian Michelle Shapiro, RD of Michelle Shapiro Nutrition LLC.
“During mechanical (physical) extraction, the germ component is separated from the kernel during the milling process to produce flour. The leftover germ is dried and then pressed using a hydraulic or screw press (i.e. “expeller-pressed”), to yield the liquid oil portion. To isolate the oil from physical contaminants, the product is washed with a chemical solvent, usually, hexane, which is evaporated to yield the oil itself,” she says.
After the physical extraction comes a chemical refining process. The goal here is to remove any unwanted contaminants that negatively affect taste, odor, shelf-life and/or smoke point (among other things). Shapiro explains that chemical refining involves six main steps1: degumming, neutralization, washing/drying, bleaching, dewaxing, and deodorizing.
All this processing comes with a major downside. “Though the purpose of the extraction and refining process is to remove undesirable compounds from the oil, it may also remove desirable compounds such as certain vitamins or antioxidants,” Shapiro says.
Some of these compounds may include beneficial fatty acids and antioxidant-rich color pigments.
Since corn oil has a high smoke point (450 degrees Fahrenheit2), it’s frequently used in cooking and frying. “You may find it in salad oils, frying oils, margarine, or foods containing these ingredients,” Shapiro says.