Can Cooking Oil Evaporate? (Common Reasons Explained And How To Stop It)
Cooking oil is a staple in many homes, but it’s not always easy to keep it fresh. In fact, some people are wondering: is cooking oil evaporating?
If this is something you’ve been wondering about, you’re in luck! Because we’ve brought together some of the most common reasons why cooking oil can evaporate and how to stop it from happening.
Can cooking oil evaporate?
Generally speaking, yes and no. The chemistry behind the difference between cooking oil and water lies in the molecular weight of the compounds that make up oil.
Typical cooking oil molecules are heavy compared to water. It’s for this very reason when heated to a certain degree, the heat will break apart its molecular structure, cause it to decompose, and become black smoke. However, oils do evaporate when left alone, but it can take months to even years.
Let’s talk about how oil would evaporate in normal conditions.
How long does it take for cooking oil to evaporate?
To better understand how and when oil evaporates, we must first understand 2 categories of oils. One is named volatile oils and the other is called fixed oils.
Volatile oils come from mainly plants and their leaves, roots, petals, and bark. These are considered essential oils. These oils will often evaporate fully and completely.
This can usually take several days and even weeks to occur. The evaporation process usually results in very little to no residue left.
These types of oils are mainly used in perfumes.
As for fixed oils, these are usually considered our cooking oils. Fixed oils contain a much higher concentration of fatty acid and glycerin. The major source of these oils comes from seeds and when it evaporates, it does so leaving behind a sticky residue.
The process of evaporation for fixed oils can take months to even years.
Does oil evaporate at room temperature?
Cooking oil can evaporate at room temperature, but the rate of evaporation is generally slower than when it is heated and only until the concentration of gaseou oil and liquid oil is in equilibrium.
The rate of evaporation depends on various factors, including the type of oil, the surface area exposed to the air, the humidity levels, and the temperature.
Some cooking oils are more prone to evaporation at room temperature than others.
For example, oils that are high in unsaturated fatty acids, such as canola oil, tend to evaporate more quickly than oils that are high in saturated fatty acids, such as coconut oil.
What causes oil to evaporate?
Generally speaking, the main reason why oil, or any other liquids for that matter, evaporates is due to kinetic energy.
I think this video gives an amazing explanation about how evaporation, in general, works.
Think about molecules. It’s always moving even within oil. Now, the degree of evaporation is mainly a result of the distribution of speeds that a molecule inside a substance like oil has.
Molecules that move really fast has a more likely chance of leaving the liquid phase as gas.
One thing that plays a big role into the rate of evaporation is the weight. Oils, compared to plain water (H2O), are made up of large molecules. There are tons of carbon chains linked together to make oil.
What happens when oil evaporates?
It could take a really long time for oil to evaporate. But in regards to cooking oil, when it evaporates it leaves behind a varnish or residue. This residue ends up staining almost anything it touches.
You can actually see these varnish stains left over on the pots and pans in your own home. The varnish in pots and pans don’t happen by normal evaporation. These were accelerated by heat. But the basic idea is still there.
How can you prevent your cooking oil from evaporating?
Cooking oil can evaporate during the cooking process due to the high heat. Here are a few tips to prevent your cooking oil from evaporating:
- Use a lid: Cover your pan or pot with a lid while cooking. This will trap the heat and prevent the oil from evaporating too quickly.
- Use a lower heat setting: Cooking at a lower heat can help prevent your cooking oil from evaporating too quickly. This is especially important if you are using a delicate oil like extra-virgin olive oil.
- Use a deeper pan: Use a deeper pan or pot to reduce the surface area of the oil exposed to the air. This can help slow down the rate of evaporation.
- Use a different oil: Certain oils like avocado oil and ghee have higher smoke points, which means they can withstand higher temperatures without evaporating too quickly.
- Use less oil: Using less oil in your cooking can also help prevent it from evaporating too quickly. Try using a non-stick pan or adding a small amount of oil to your pan and spreading it out with a brush or paper towel.
- Store oil properly: Store cooking oil in a cool, dark place away from direct sunlight and heat sources. It’s also important to keep the container tightly sealed to prevent air and moisture from entering and accelerating the rate of evaporation.
How does heating cooking oils affect the evaporation rate?
Heating cooking oils can increase the rate of evaporation. When cooking oils are heated, the heat energy causes the oil molecules to become more active and move faster.
Because of this increased molecular activity, more oil molecules can escape into the air as vapor, which makes the rate of evaporation go up.
Also, cooking oils have different smoke points, which are the temperatures at which they start to break down and smoke. When an oil gets to its smoke point, it can make harmful chemicals and speed up the rate at which it evaporates.
Does cooking oil evaporate at room temperature?
Cooking oil can evaporate at room temperature, but the rate of evaporation is generally slower than when it is heated. The rate of evaporation depends on many things, such as the type of oil, how much of its surface is exposed to the air, the temperature, and the level of humidity.
Some cooking oils are more prone to evaporation at room temperature than others. For example, oils that are high in unsaturated fatty acids, such as canola oil, tend to evaporate more quickly than oils that are high in saturated fatty acids, such as coconut oil.
How long does it take for cooking oil to evaporate?
- At high temperatures, cooking oil can evaporate quickly, especially if the pan is uncovered. For example, when frying food in hot oil, some of the oil can evaporate within a matter of minutes.
- When the oil is heated at a lower temperature or covered with a lid, the rate of evaporation can be slower.
At room temperature
- The rate of evaporation at room temperature is slower than when the oil is heated.
- The time it takes for cooking oil to evaporate at room temperature can vary from a few days to several weeks, depending on the type of oil and the conditions in which it is stored.
- Oils with lower smoke points, such as canola oil, tend to evaporate more quickly at room temperature than oils with higher smoke points, such as olive oil.
What is the boiling and smoking temperature of cooking oil?
The exact boiling point of oil really depends on the purity of the oil itself. Typically speaking, palm cooking oil, which is considered 100% fat, is estimated to boil up to as high as 300°C (572°F).
However, well before oil boils, it firsts goes through the smoking phase. The smoke point is a measure that’s almost exclusive to oils and this may sometimes cause your food to have that burnt flavor.
|Cooking Oils||Smoking Points|
|Olive oil||190°C (375°F)|
|Canola oil||205°C (401°F)|
|Sunflower oil||225°C (437°F)|
|Peanut oil||250°C (437°F)|
|Corn oil||230°C (446°F)|
|Palm oil||235°C (455°F)|
|Soybean oil||257°C (495°F)|
What should you do when cooking oil starts to smoke?
When cooking oil starts to smoke, it is an indication that the oil has exceeded its smoke point and has started to break down. Cooking with oil that has reached its smoke point can produce harmful compounds and also increase the risk of a fire hazard.
Here are the steps to follow when cooking oil starts to smoke:
- Turn off the heat source: Immediately turn off the heat source, whether it is a stovetop burner or an oven.
- Remove the pan from heat: If the oil is in a pan or pot, remove it from the heat source to prevent it from getting any hotter.
- Let the oil cool: Allow the oil to cool down for several minutes. Do not attempt to move or handle the pan until the oil has cooled down, as hot oil can cause serious burns.
- Discard the oil: Once the oil has cooled down, carefully pour it into a heat-resistant container, such as a glass jar, and dispose of it properly. Do not pour the oil down the sink or toilet, as it can clog the pipes.
- Clean the pan: Clean the pan thoroughly with soap and water to remove any residue and prevent it from smoking again in the future.
Does frying oil evaporate?
Again, let’s go back to the idea of kinetic energy. Now, kinetic energy is proportional to its temperature. Higher temperatures will cause molecules within the oil to move faster and potentially allow it to break free from the hoard.
So the answer is yes, frying oil does cause the oil to evaporate to a certain degree. However, exclusive to oil and fat is the smoking point.
During cooking, the oil will smoke long before it actually evaporates. This is when instead of simmering over a hot flame, the oil will let out some serious smoke after reaching a certain temperature.
Be wary, the oils can reach a certain temperature in which they go into something called a flashpoint. At this point, you need to know that it can produce ignitable gas. Don’t let it get to this point.
Luckily for me, my oil had only gotten to the point of smoking and that’s when I cautiously turned off the stove and kept an eye on it until it settled down.
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