When oil reaches a high temperature during frying and deep frying, secondary products can form that are bad for your health.
While many believe that oils with a high smoke point are best for high temperature cooking, recent research has shown that it’s not the best metric to go by.
I’ll summarize that research in an easy to understand way so that you can choose your frying oil with confidence. Spoilers, extra virgin olive oil is the very best.
A Summary of The Effect of High Heat on Cooking Oils
We’ve known for a long time that cooking at high heats can produce secondary products that are unhealthy, especially when it comes to oils. This applies to all oils, vegan or not.
Ideally, cook at as low of a heat as possible.
As oil is heated, it can produce harmful products like (Source):
- Free radicals
- Trans-fatty acids
- Conjugated linoleic acids
- Oxidized volatile products
- And more…
It’s hard to measure some of these directly,
What most countries use to determine whether a cooking oil is safe or not is the level of Total Polar Compounds (TPC), which includes:
Polar compounds consist of dimeric and higher polymeric triglycerides formed through thermal polymerisation of triglycerides, monomeric oxidised products, as well as mono- and diglycerides and free fatty acids formed through hydrolytic cleavage of triglycerides
The more degraded an oil is, the higher the TPC is.
Most countries set an upper limit for frying at a TPC level of 25-27% (Source). If the food will be stored for an extended period, an upper limit of 10% is recommended.
The Best Vegan Cooking Oils for Frying Ranked
A research team in Australia took ten cooking oils from a supermarket and tested them in great detail (Source).
They tested them in 2 ways:
- Pan fried, reaching a maximum temperature of 240ºC (464ºF) after about 20 min
- Deep fried at 180ºC (356ºF) for 6 hours
Measurements were taken at regular intervals.
Note that no food was being cooked (it was just oil being heated), which may have affected the results.
Here’s a summary of the most important findings that we’re interested in.
|Oil type||Final Polar Compounds (%)||Smoke Point (C)||Smoke Point (F)|
|Extra Virgin Olive Oil||8.47||206.67||404.0|
|Virgin Olive Oil||10.71||175.33||347.6|
|Rice Bran Oil||14.35||237||458.6|
Note that smoke point has little effect on the level of polar compounds (TPC). Grapeseed and sunflower oil have high smoke points, but also have a high level of TPC after cooking at a high temperature.
Smoke point tells you when an oil will smoke, it’s not a good indicator of unhealthy compounds in heated oil. It still might be important because you don’t want your kitchen filled up with smoke during really high heat cooking.
What’s The Best Vegan Oil For Frying and Deep Frying?
You’ll have to make your own call based on the temperature that you’re cooking at.
Ideally you want to stay under the smoke point of an oil for obvious reasons.
However, if you’re not cooking at super high temperatures, the best vegan oils for frying and deep frying are:
- Extra virgin olive oil
- Coconut oil
- Virgin olive oil
- Peanut oil
All of those have roughly 10% or less of total polar compounds after cooking, which means that they are “safe” to eat even after storage.
There are 2 final things to consider:
- Oil quality – There are lots of “fake” oils out there, and those ones are almost certainly going to perform worse in any conditions.
- Other aspects of oil – Some people want to avoid coconut because of saturated fat, or prefer another because of taste, and so on. The healthiness of oil in general is a much longer discussion than I can cover in this post.