From cold-pressed extra-virgin olive oil to unrefined coconut oil to vegetable oil, the growing range of options for cooking oils seems to be increasingly more complex. Oils are most commonly pressed or processed through two methods such as those that are heavily filtered and are called “refined” or minimally filtered, and are called “unrefined.” Refined oils are stringently filtered and heavily processed to remove impurities or food particles left behind by the extraction process. Unrefined oils are gently processed in an effort to keep the oil as close to its natural state as possible. These two processing methods affect nearly every characteristic of refined and unrefined oils, including flavor, nutrient density, shelf life and the temperatures to which the oils may safely be heated.
Read the label to learn more about the oil. Unrefined oils will often be labeled in a noticeable location, such as the front of the bottle or canister. If there is no label, it can generally be assumed that the oil is refined.
Evaluate the color and consistency of the oil. Refined oils are clear in appearance due to the heavy filtration process they undergo. Unrefined oils generally have a cloudy appearance and may collect food particles and sediments at the bottom of the bottle.
Consider the price and accessibility of the oil. The most common refined oils include olive oil, vegetable oil, canola oil and sunflower oil and are carried at grocery stores, markets and even convenience stores. Unrefined oils are more difficult to find, making them slightly more expensive than refined oils. The choices at your local grocer may be minimal, but you can likely find a variety of unrefined oils at stores that focus on organic or health foods. Unrefined coconut oil is one of the most common types of unrefined oil.
Taste the oil, when possible, to help determine whether it is refined or unrefined. Refined oils taste mild because most of the flavor is lost during the filtering process. Unrefined oils are quite robust and dominant in flavor.
Tips & Warnings
- Most oils are sold in both refined or unrefined form.
- Unrefined and refined oils should be kept in a cool, dry location free of direct sunlight, such as a pantry or kitchen cabinet.
- Both types of oils may solidify in the refrigerator, but it is safe, and sometimes, even recommended to store oils there.
- As with most heavily processed foods, refined oil has a longer shelf life than unrefined oil. Shelf life varies, however, according to the type of oil so always be mindful of the expiration date listed on each oil-based product you purchase.
- Refined oil loses most of its nutrients during the filtration process, while unrefined oil is touted for maintaining most of their nutrients through the gentle filtration process.
- Both unrefined and refined oils are sensitive to oxygen and light; heavy exposure to either can greatly diminish flavor and nutrient density.
- Heating unrefined and refined oils higher than the recommended temperatures can increase oxidation – a process by which the oil is compromised by a chemical reaction. Many refined oils can withstand temperatures higher than 450 degrees Fahrenheit while unrefined oils should be used in recipes that require cooking temperatures lower than about 320 F.
- Beware of misleading product labels. Words like "cold-pressed," "virgin" and "expeller pressed" can confuse consumers and don't necessarily mean the oil is healthier. For example, expeller-pressed oils are generally refined, unless noted otherwise on the label.
- Photo Credit Kraig Scarbinsky/Photodisc/Getty Images