Psst... We're working on the next generation of Chowhound! View >
HOME > Chowhound > General Topics >
Feb 29, 2008 06:59 PM

Deep frying with Canola Oil


I was wondering if I were to be deep frying with 100% pure canola oil at home, would the oil eventually generate trans fat? What if I reused this oil to deep fry again as well?


  1. Click to Upload a photo (10 MB limit)
  1. I have no idea what the trans fat properties might be, but Canola Oil (of the high-heat variety if I can find it), is one of my frying fats of choice. Peanut Oil comes first, but in a pinch I've fried plenty of savory and sweet items alike in Canola. I've had zero problems bringing the temperature to well above 375 Fahrenheit and when finished, I simply run the cooled oil through a fine-mesh strainer and store in the refrigerator for at least a couple of additional uses. If you're frying at home and avoiding fast food eateries I can't really see anything wrong (health-wise) to cause any major concern.

    R. Jason Coulston

    1. Canola oil, because of its fat profile, has the unfortunate tendency of getting a distinctly fishy taste that is perceptible by many (not all) people. If you've ever had fishy-tasting french fries, you will konw what I mean. If you and your guests are all people who cannot tell the difference, then this is not an issue. There are also lingering non-urban myth issues (that is, there are issues that are unresolved) regarding canola at high temperatures. In any event, I don't use or recommend canola - it has a great marketing campaign but there are better oils. For high heat, peanut, grapeseed (pricey) and soy are my go-to oils.

      18 Replies
        1. re: jayt90

          They concern whether canola oil forms unhealthy compounds over prolonged exposure to high heat.

          1. re: Karl S

            There is some information here about excessive wok hai heating temperatures of unrefined rapeseed oil in China causing problems.


            1. re: jayt90

              It's so comforting to see such guaranteed true and unbiased information from a neutral scientific source :-)

              And remember, the Chinese are using rapeseed, and Canola is NOT rapeseed.

              And Canola oil is not genetically modified - only the plant is! Huh?

              And Roundup Ready canola seed has -reduced- pesticide use. (Funny, but I thought that this seed was used so that actively growing Canola crops could be directly sprayed with Roundup without hurting the genetically modified plants. Gosh. I guess I must be misinformed. So sorry.)

              Websites like that one make me embarrassed to be Canadian.

              Whatever. The oil still makes lousy frites.

              1. re: embee

                Well, I asked for information about problems with canola and no good information appeared here, so I did a search. At least the canola people have provided information to counter their critics. I haven't seen much else.
                BTW has Monsanto got control of seeds for soybean, peanut, corn or cottonseed oil? I guess that's another search.

                1. re: jayt90

                  Again, no real information on this board about GM corn oil, peanut oil, or soybean oil, so I looked it up.

                  Corn oil and soybean oil are universally pressed from genetically modified crops in North America, and the peanut industry received approval for Monsanto GM seeds in 2006, so this too will follow. The only way to avoid GM oil will be the health food market.

                  I didn't look into cottonseed because it is a minor player, and not considered a true oil by some, but GM and hybridization are permitted.

                2. re: embee

                  What do you mean canola is not rapeseed? It's rapeseed oil.

                    1. re: Karl S

                      Yes, of course it is. I was being sarcastic. Check the link in jayt90's post above, which takes you to the Canola Council of Canada's website.

                      In their words, Canola isn't rapeseed and Canola oil isn't genetically engineered - only the plant is. As I said in my post, I found this site embarrassing. I expect spin from a lobby group, and there is some interesting information on the site, but some of their claims are so far out that they make my head spin. Read it and weep.

                        1. re: MMRuth

                          I reread the site more carefully and it gets worse. Canola isn't rapeseed but rapeseed is Canola. It really says that. Look under the "banned in the EU" section.

                          1. re: embee

                            How would you prefer your food to be fried? The other vegetable oils produced in North America are from hybridized and genetically modified plants. (Peanuts are not yet GM, but that too is changing.)

                            Only a few restaurants and home kitchens will deep fry in olive oil, and use of tropical oils or animal fats won't fly any more.

                            1. re: jayt90

                              Nothing beats beef fat for deep fried potatoes. (In a different vein, there's no substitute for coconut oil-popped popcorn.) At home, I usually deep fry with peanut oil, which is undoubtedly too costly for mainstream commercial use and carries high profile allergy implications. I have used olive oil (not evo), and the results were delicious, but it's really too expensive even at home.

                              Beyond that, sunflower, corn, and even soybean can be okay. Note that I'm not addressing either health implications or GM plants. Canola seems fine when used cold in dressings and the like, but food deep fried in Canola never seems to taste all that good. Most restaurants using Canola seem to have switched from solid trans fat shortenings. Perhaps Canola needs some specific skills, different temperatures, and/or different timings. All I know is that it also hasn't worked well for me when I've tried it at home.

                        2. re: embee

                          Canola oil is not genetically engineered, only the plant. Genetic engineering has to do with the proteins, the oil has no proteins, hence no DNA and without DNA, genetically modiffied means nothing.

                      1. re: embee

                        "Canola was developed through conventional plant breeding from rapeseed" - Wikipedia. Canola is NOT a GM seed in of itself. Yes there are Genetically modified types of canola and these are the disease- and drought-resistant variety along with higher oil content varieties. The disease resistant varieties used DNA from other plant DNA to acheive this. The high oil content varieties uses DNA from Fish. There are therefore 3 "types" of canola, non-GM, GM and GMO.

                        Yes the plant can be genetically modified and the oil not. Genetics have to do with the proteins, oil has absolutely no proteins (I have first hand knowledge), therefore worrying about whether or not canola oil is from a GM or GMO species is actually irrelevent. If you were a cow fed with it, that may be a different story though (and then if you eat that cow possibly).

                        1. re: annom

                          On what do you base the claim that genetic modifications "only have to do with proteins"? The whole point of genetic modification is that it either causes the plant to produce substances with a more desirable composition (like oil with a different composition of fatty acids) or to change the chemical processes within the plant itself to make it more resistant to disease, drought and more importantly for agribusiness, chemicals like Roundup. The oil may not have proteins, but that doesn't mean that its characteristics haven't been altered by means of genetic modification of the plant.

                3. re: Karl S

                  Is soy oil different from vegetable oil?

                  1. re: rumgum

                    Vegetable oil often is just soy oil but may be any combination of vegetable oils (soy and corn are a common combo in the US) - just read the label.

                4. Canola is an engineered rapeseed oil. In it's natural form, this oil is toxic. It has been a marketing triumph for Canadian farmers, and for Monsanto, with the cholesterol/saturated fat/trans fat panic of recent years. On paper, Canola has a fat profile that superficially resembles that of olive oil. We have been led to believe that it is healthy.

                  Unfortunately, Canola oil doesn't taste good. As another post notes, Canola tastes distinctly fishy to many people. But even if this problem doesn't affect you, Canola is a really crappy deep frying oil. If a restaurant where you've loved the fried food for years suddenly starts serving fried foods that don't taste good any more, ask them whether they've switched to Canola. Canola fried French fries = blah (assuming they don't taste fishy).

                  6 Replies
                  1. re: embee

                    Unheated Canola oil is rather neutral. I do agree with you that heating it up to high temperatures makes it stink.

                    1. re: embee

                      This has been a very interesting post. We were frying with with canola the other day, and indeed, I noticed that fishy smell that everyone has been commenting on. I did find it a bit off putting, enough to turn on our fan. But in terms of the taste, I can't completely agree that it is bad. My mom has been frying her famous homemade Korean eggrolls for a long time in this oil, and I can tell you that they remain very popular. And her fried squid tempura were great too. I was trying to find the fishy taste, but fortunately, all I could taste was the fried yumminess of the eggrolls. Maybe I am lucky in that I can't taste the fishy smell. although I do usually taste too many odd flavours rather than too little.

                      This is a difficult subject. Peanut oil would be my next choice, but it is higher in saturated fats than canola. Grapeseed might be good, but it is expensive. I tried olive oil, and that was pricy too. Well, we don't fry that often, on account of it being less healthy than for example steaming. May be it would be worth splurging for the few times we fry (and more of a deterrent to fry).

                      But dang. Fried food is so good.

                      1. re: moh

                        Korean eggrolls? Sounds intriguing. Is that like mandoo with more veggies in an eggroll format?

                        1. re: Miss Needle

                          It is my mum's mandoo filling (cabbage, onions, vermicelli noodles, mushrooms, peppers, carrots, seasoned beef and pork) in a mandoo triangular shaped wonton skin. Then deep fry. Much less cabbage than most commercial chinese style eggrolls. She will also boil them and serve them with kang jan (soy sauce based sauce). When she fries them, it is a real treat! They are very famous in the Winnipeg Hospital system.She is a retired nurse, and she used to make them every Christmas and sell them to raise money for the Korean church and her alumni association. When she retired, she had to continue making the eggrolls at Christmas, because people begged her for them. She also managed to trade them for a Ukrainian grandmother's recipe for pierogies, so now she makes great pierogies too.

                          1. re: moh

                            Wandering if there is anyway for a couple of recipes to be shared? Please??? I luv the real family stuff. Especially since I don't know how to make any of that.

                      2. re: embee

                        Most people find when switching to canola, the taste isn't what they are used to and is actually blander than what they like. This is a personal preference. The remarks about canola oil being fishy in flavor is misleading. The fishy flavor is from rancidity of the oil and/or improper refining, bleaching and deodorization parameters. I have deep fried french fries from freshly deodorized oil and there is absolutely no fish flavor. It is a very clean taste. Good canola oil doesn't have any flavor at all. I know as I worked as a Lab tech in a canola crush plant for 10 years and we had to taste each shipment of oil and each sample out of the deodorizer. If it tasted fishy (I could name 10 other flavor discriptions), it would have been rejected. If you have fishy tasting canola oil, somebodies quality control is not up to snuff.

                        Also, I don't have much creadance in all the low trans, low saturated, no cholesterol media frenzy propaganda that gets pushed around. But, if the oil really was bad for you, over the 10 years of flavoring and hence swallowing some of the oil, I should be in serous condition, and I'm not.

                      3. i read that cannola, before being used for cooking was actually for machinery...plz read into it, dont recall how it became good for people.

                        i like canola because its cheap, it does have some trans fat, but its very very very should not use oil to deep fry to many times, your oil will saturate and be nasty..

                        can someon tell me the difference between saturated fat in oil and doesn't seem like the same thing...

                        1 Reply
                        1. re: Echotraveler

                          Water is also used for machinery. Does that mean you should stop drinking water?

                          There are a variety of plants that are poisonous. Tomato plants, apples, pears, peaches, bracken... To name a few.

                        2. You can't generate trans fat from heating the oil. Trans fat is generated by hydrogenation. This makes the oil solid at room temperature. It's a good bet that your oil is not solid after repeated deep fryings.

                          2 Replies
                          1. re: Shazam

                            Um, yes you can generate trans from heating the oil, if its hot enough. The smoke point for canola oil is 232ºC minimum. Trans fat formation starts to rise exponentially after 220ºC. And, if you are deep frying chicken or anything with animal fat in it, the canola oil can start to solidify when it cools because of the introduction of lard from the food.

                            1. re: annom

                              My goodness. The amount of transfat formed is very small. Perhaps if you cool and reheat the oil a few dozen times you might have to be worried.