What oil do you use for your cooking? How many different oils do you have in your pantry? How many do you need? Explaining the myriad of oils and how to use them is the subject of this and the following Cooking Tip.
There is really no one all-purpose oil for culinary purposes. It depends on how you are going to use the oil. Although it is fun to try many different varieties of oil, you don’t need multiple kinds on a day-to-day basis. In this Tip, I will discuss the processing and terminology associated with culinary oils. In the next Tip, we will delve into some of the oils that you can buy.
There are a myriad of differences among culinary oils.
- Source – what is used to make the oil such as olives, nuts, corn or other plants.
- Flavor – some oils are very neutral in flavor while others carry a flavor from their source. Do a side-by-side taste testing of extra virgin olive oil and canola oil for an example. Deciding whether or not you want the flavor of the oil in your dish will help you decide which oil to use.
- Smoke point – this is the temperature at which an oil starts to break down. As this happens, toxic fumes and harmful chemicals can be released. If you are cooking something that requires a high heat, you will want to use an oil with a higher smoke point. If on the other hand, you are using the oil to make a vinaigrette, smoke point is irrelevant. Here is a chart compiled from information on Serious Eats that shows the smoke points for different oils.
- Processing – is the oil obtained with a chemical process or expeller processed?
- Extraction
- According to Centra Foods (a supplier of bulk oils), the fruit/nut/seeds are first ground into a paste. Next, this is washed with a solvent, commonly hexane, to release the fat. The solvent is then removed by heating it in a sealed chamber. Centra Food states the oil is left with “virtually no detectable levels in the oil (if the proper techniques have been applied). Microscopic proportions of up to 25 parts per million of hexane can theoretically remain in the meal, which is a very high debate point in the natural food industry.”
At this point, the oil is considered “unrefined”. This is then subjected to further processing known as “RBD” – refined, bleached & deodorized. (These oils are sometimes known as RBD oils). This produces an oil that is light in color and flavor. This extraction method is very efficient, getting 97-99% of the oil out of the fruit/nut/seed. This is one reason why oil produced by this method is less expensive.
- According to Centra Foods (a supplier of bulk oils), the fruit/nut/seeds are first ground into a paste. Next, this is washed with a solvent, commonly hexane, to release the fat. The solvent is then removed by heating it in a sealed chamber. Centra Food states the oil is left with “virtually no detectable levels in the oil (if the proper techniques have been applied). Microscopic proportions of up to 25 parts per million of hexane can theoretically remain in the meal, which is a very high debate point in the natural food industry.”
- Extraction
- Expeller pressed
- With the expeller method, oil is physically squeezed out under high pressure using a screw press. It can be termed either hot- or cold-pressed. Expeller pressing is not as efficient and thus, the oil is higher priced. Since it undergoes fewer chemical changes, manufacturers claim it has a more natural flavor with less damage to the nutrients. Hot pressed – with this method, heat is added prior to extraction. This makes it easier to extract the oil by cooking and drying the fruit/nut/seeds. Typically, this method can extract 87-95% of the oil. It can be used in sauteing, baking or in salad dressings where you are not looking to taste the oil. Cold pressed – there is no heat applied before extraction. Without the heat, the screw press must work harder and apply more torque. This causes friction, which can generate some heat although it has not been applied before the pressing process. To compensate for this heat production, a water cooled shaft is used to keep the press as cool as possible. It must be kept below 120°F at all times. The manufacturer may also use heat to dry the fruit/nut/seeds for storage. Centra Foods states that an oil should only be termed “cold pressed” if it is fully unrefined and heat is not applied at any part of the process. This removes the least amount of oil, making it the most expensive type of oil. It will also have the lowest smoke point.
Although it is possible to cold press any fruit/nut/seed, this is most commonly done with certain types of olive oil and coconut oil. Chefs recommend saving this oil for uses where you want to taste the distinctive flavor of the oil and with foods that will not be cooked. Examples are vinaigrettes, marinades, dipping oils and frozen treats.
- Most common to find in the supermarkets are oils made by the chemical extraction process. If the label does not list “expeller pressed” or something similar, it will be extraction oil.
- With the expeller method, oil is physically squeezed out under high pressure using a screw press. It can be termed either hot- or cold-pressed. Expeller pressing is not as efficient and thus, the oil is higher priced. Since it undergoes fewer chemical changes, manufacturers claim it has a more natural flavor with less damage to the nutrients. Hot pressed – with this method, heat is added prior to extraction. This makes it easier to extract the oil by cooking and drying the fruit/nut/seeds. Typically, this method can extract 87-95% of the oil. It can be used in sauteing, baking or in salad dressings where you are not looking to taste the oil. Cold pressed – there is no heat applied before extraction. Without the heat, the screw press must work harder and apply more torque. This causes friction, which can generate some heat although it has not been applied before the pressing process. To compensate for this heat production, a water cooled shaft is used to keep the press as cool as possible. It must be kept below 120°F at all times. The manufacturer may also use heat to dry the fruit/nut/seeds for storage. Centra Foods states that an oil should only be termed “cold pressed” if it is fully unrefined and heat is not applied at any part of the process. This removes the least amount of oil, making it the most expensive type of oil. It will also have the lowest smoke point.
- Virgin vs Extra Virgin
- Both of these terms apply to cold-pressed oils. Extra virgin means it is oil collected from the very first pressing. Virgin oils are from the second pressing, resulting in less flavor and aroma. These terms are mostly used with olive and coconut oil.
In 2010, the USDA issued the “United States Standards for Grades of Olive Oil and Olive-Pomace Oil.” However, these standards are voluntary. So, producers may choose to seek certification by the USDA as “US Extra Virgin Olive Oil” if they wish, but that it is not mandatory. See this Cooking Tip on Extra Virgin Olive Oil for more information and why you may not be able to rely on these terms in the supermarket.
These USDA standards do not apply to coconut oil. Since there is no legal standard for the terms “virgin” and “extra virgin” as applied to coconut oil, there is no consistency among the usage of these terms by manufacturers. In fact, one manufacturer, Carrington Farms, has dropped the use of the term “extra virgin” and opted for “Virgin, Unrefined”. You will, though, see certain brands still use the term “extra virgin”, probably attempting to piggyback off the popularity of extra virgin olive oil.
- Both of these terms apply to cold-pressed oils. Extra virgin means it is oil collected from the very first pressing. Virgin oils are from the second pressing, resulting in less flavor and aroma. These terms are mostly used with olive and coconut oil.
A final comment about storage. Oil does not last indefinitely and must be stored properly. Since heat and light can damage oil, store it in a cool, dark place. In that case, most oils can last up to a year. There are specific oils, though, that require refrigeration. Check the label but examples are grapeseed and nut oils. Some culinary experts recommend storing all your oils in the refrigerator. If you did that, some may thicken and you will need to let them sit out on your counter a few minutes to come to room temperature. Stay tuned for next week’s Tip as we look at individual oils that you might to use.
Culinary Journeys, LLC 