Everyone knows what we’ve been told for years that saturated fats, like real butter, are bad for us and that polyunsaturated fats are good for us. That may be true at room temperature but what about when cooking, say at frying temperature 356F (180C)?
According to this report from BBC 2 things change radically at those temperatures. What follows is a summary of that report.
“Professor Martin Grootveld from De Montfort University has shown that when we heat oils and fats other, more dangerous, chemical reactions occur which alter the molecular structure of the oils and fats and create new compounds which could be harmful to our health. And this could completely change the advice we should all follow when choosing a cooking oil.”
Research has shown that thermally stressing fats and oils can change their structure by means of oxidation. “Studies have shown that consuming or even just inhaling these oxidative products have can some negative health effects and they have been linked to an increased risk of heart disease and cancer.”
The report showed that the oils (the good oils) “which were rich in polyunsaturated fatty acids, like corn oil and sunflower oil, generated very high levels of oxidative products known as aldehydes. By contrast, the fats and oils which were rich in saturated fatty acids or monounsaturated fatty acids (like butter or olive oil) produced far fewer aldehydes and other potentially dangerous products.”
So if you want to avoid these potentially dangerous products “Martin suggests that you go for an oil or fat high in monounsaturated or saturated lipids (preferably greater than 60% for one or the other, and more than 80% for the two combined), and low in polyunsaturates (less than 20%). Olive oil is a good compromise because it is about 76% monounsaturates, 14% saturates and only 10% polyunsaturates.”
| Type of oil or fat | Polyunsaturated (%) | Monounsaturated (%) | Saturated (%) |
| Coconut oil | 2 | 6 | 86 |
| Butter | 3 | 21 | 51 |
| Lard | 11 | 45 | 39 |
| Goose fat | 11 | 56 | 27 |
| Olive oil | 10 | 76 | 14 |
| Rapeseed oil | 28 | 63 | 7 |
| Sesame oil | 41 | 40 | 14 |
| Corn oil | 54 | 27 | 12 |
| Sunflower oil | 65 | 20 | 10 |
My personal choice for stir frying is Coconut Oil. This report shows that “even after 8 hours of continuous deep frying at 365°F (180°C), its quality does not deteriorate.”
