WHICH COOKING OIL SHOULD I USE?
If you are confused about which oil to use for cooking, you are not alone.
We use them daily, and each of us has a specific preference to one or another, due to habits or culture.
I scanned a handful of random websites to see what information they were providing and let me tell you that many just care about the taste, without considering the health effects.
Not all oils are good for everything, so an important question to ask is: what am I cooking?
When we heat oils/fats, their structure changes, becoming instable depending on the oil and the temperature it was heated. Each oil/fat has a different smoking point, that is the temperature at which the oil starts to burn. If the oil burns, then is not providing any benefit and it will increase the oxidative stress. Oxidative stress is an imbalance of free radicals that create damage in our cells, and antioxidants that inhibit damage. This is crucial, because what we eat should provide us with nutrients that fuel and nourish our body instead of causing harm.
Each oil/fat has a unique mix of saturated, monounsaturated and polyunsaturated fatty acids. We have heard that polyunsaturated fatty acids are the healthiest, so you would think that we should use those, right? Polyunsaturated-rich oils, like corn oil, sunflower oil and sesame oil, are actually very unstable at higher temperatures and produce toxic compounds called aldehydes.
Research found that oils/fats that contain higher amounts of saturated fats tend to be more stable at higher temperatures. We are talking about butter and coconut oil.
Extra virgin olive oil, goose fat and lard are higher in monounsaturated fatty acids, making them ideal for cold or low heat.
Finally, oils that are high in polyunsaturated fats, like corn, sunflower and sesame, should not be heated at all.
Another issue that I want to address, is the type of container used to store the oil. Because oils are very fragile, their proximity to sources of heat and/or light can damage them and decrease their antioxidant intake. The best way to store them is by using a dark glass bottle (usually dark green), as it precludes light to come into contact with the oil. If you see any oil in a plastic or transparent bottle, please steer clear, that oil is already damaged.
FRIDGE OR ROOM TEMPERATURE?
Because we mentioned that oils are very sensitive to sources of heat, you might want to keep them in the fridge, particulary flaxseed and nut oils. Fridge can alter the taste and texture of olive oil, so I would opt to keep it in a cool place, away from light. Butter, of course, must be kept in the fridge.
CAN OIL GO OUT OF DATE?
The “use by” date that you find on the bottle can be a bit misleading, it assumes that the oil is kept closed and stored away from heat and light. The reality is that you will open it, and possibly keep it near the stove, ready for grab. As a guideline, and in normal conditions, let’s have a look at the most common oils and their shelf life.
Olive oil and coconut oil have a longish shelf life, which is usually 2 years from the manufacture date, and about 12 months from the opening date. Flaxseeds and nut oils are very unstable and prone to oxidation, hence I wouldn’t keep them open for longer than 4 months.
Remember that the sooner you use your oil, the more antioxidants you will get into your food.
Buy high quality oils/fats in dark glass bottles and select the appropriate ones depending on the meal that you are preparing. Keep them in a cool, dark place to preserve their antioxidant content and deliver more nutrients into your food. Do not buy big quantities unless you know that you will use them within 4 to 6 months, otherwise will go rancid.
Grootveld, M. Silvood, C.J. Addis, P. et al. (2001). Health effects of oxidised heated oils. Foodservice research International, 13: 41-55. https://doi.org/10.1111/j.1745-4506.2001.tb00028.x.
Kochhar, S.P. Henry, C.J. (2009). Oxidative stability and shelf-life evaluation of selected culinary oils. International Journal of Food Sciences and Nutrition, 60 Suppl 7:289-96. doi: 10.1080/09637480903103774. Epub 2009 Jul 25. PMID: 19634067.
Li, H. Fan, Y.W. Li, J. Et al. (2013). Evaluating and predicting the oxidative stability of vegetable oils with different fatty acid compositions. Journal of Food Science, 78(4):H633-41. doi: 10.1111/1750-3841.12089. Epub 2013 Mar 25. PMID: 23527564.