RE: Trans Fat Free Soybean Oils
This is a marketing ploy. All pure soybean oil should be "trans-fat free". So are other vegetable oils unless they've been messed with, i.e. "partially hydrogenated". Starting, I believe, on Jan 1 the Federal government required food lables to specify the trans-fat content and some companies are turning this into a marketing tool by claiming a zero trans-fat level in products that never had any trans-fat--such as pure vegetable oils.
Since this is the professional's forum, I do realize that some commercial operations (mostly large chains) have used partially hydrogenated trans-fat containing oils for frying. I'm not sure what benefits they thought they were getting by doing that--I'll guess stability and long life in the fryer--but it has always been bad for the health of their customers.
In vegetable oil, what you should look for healthwise is a high content of monounsaturated (best) and polyunsaturated (good) fat and you should find that in olive oil, most nut oils, canola oil and, to a slightly lesser degree in corn oil and so on. For frying, you also want to worry about smoke point--how much heat the oil can take--which is why many places use peanut oil for frying. And finally, you should worry about taste.