582209 Mon Dec 22 17:48:30 -0800 2008 2 31 Home Cooking 0 4267457 I use rice bran oil for deep frying, because it is free of trans fat. My wife believes that repeated use of the oil creates trans fat. Can anyone substantiate that? Urban myth? Thanks for your help. Mon Dec 22 17:48:30 -0800 2008 15172 Michael Rodriguez 1 4267770 Deep frying is bound to leave some of the chemicals from the foods being cooked in the oil itself. What those are, and how much of them remain in their natural state, is a matter for conjecture. Wouldn't we have to hydrogenate rice bran oil to create trans fats? How do we hydrogenate rice bran oil by simply heating it repeatedly? As I understand it, hydrogenation requires a high level of heat and the addition of some form of catalyst (a reactive metal) and the introduction of hydrogen gas. Is your deep fryer made from or coated with a reactive metal? (e.g. titanium, nickel, magnesium) If you can do that in your deep fryer I will agree with the theory. Otherwise, I'd have to see more scientific evidence on the subject. But, personally, I don't worry about whatever small amounts of trans fats I might ingest incidental to my carefully controlled low fat diet. Mon Dec 22 19:48:19 -0800 2008 4267457 203621 todao 1 4267947 Yes, it can. Heat creates trans fats in unsaturated vegetable or canola oil. For example, the smoke point for canola oil is 230ºC. 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. So storing/re-heating oil is something you definitely want to avoid. New frying oil isn't super healthy but old frying oil is just plain bad. If I could afford it, I'd deep fry with coconut or palm oil. Those are probably the healthiest option. If I'm am going to deep fry in refined soy or corn oil, I'm not going to make the trans fat situation any worse by re-heating. Mon Dec 22 21:27:55 -0800 2008 4267457 11583 ipsedixit