olive oil on wooden table

Yesterday I ventured out to my local supermarket to grab a bottle of trusty Extra Virgin Olive Oil.

An ‘in and out’ job.

No more than 5 minutes (depending on line length and whether anyone in front of me thinks they can do a better job than a checkout assistant by taking a trolley full of groceries through the self-serve).

So I arrived at the oils section and although I’d been there before, I’d never really taken stock of the number of different cooking oils now available to consumers.

I stood there thinking, this must have been how John Snow felt when he stood there looking at the great ice wall in front of him… Overwhelmed.

Except, instead of wondering how I would make it to the top without falling to my death, I was wondering what oil I should choose that would be healthy, tasty and applicable to the dishes I regularly cook.

There is a plethora of possible choices.

While this is great if you have an understanding of culinary oils and their uses, for the majority of us, it can be confusing and overwhelming.

To make things more complicated, each week it seems the media is telling us to “eat this fat”, “don’t eat that fat” or “add this fat to your coffee for all day energy and fat burning!” (Top tip: don’t add large quantities of any fat to your coffee).

Before we dive into all the details, lets quickly get a quick overview of oils.

Oils are essentially fats; they contain negligible amounts of carbs and proteins. Whether the oil is solid or liquid depends on whether the triglycerides (fatty acids attached to a glycerol molecule) are predominantly unsaturated fatty acids or saturated fatty acids.

Typically, animal products such as butter and lard tend to be solid at room temperature because they contain mostly saturated fatty acids. Vegetable oils derived from plants, seeds, legumes, nuts and some fruits are liquid at room temperature, due to their high levels of unsaturated fatty acids.

The obvious exemptions to this are palm oil and (the now trendy) coconut oil. These plant oils are more solid at room temperature because they contain high amounts of saturated fat.

So which do I choose?

There are a number of things to consider when choosing the right cooking oil for a particular situation.

Refined vs Unrefined

Your first question may be, refined or un-refined oil? What’s the difference between extra virgin olive oil and standard olive oil?

It’s the level of refining. Oils are refined and processed to remove any unwanted taste, smell, colour or impurities.

However, in the process of refining they also remove a lot of the beneficial compounds found in unrefined oils. For example, non-refined oils like ‘virgin’ olive oil and ‘extra virgin’ olive oil are likely to contain more antioxidant polyphenols than refined olive oil. [1]

You may think “well, why not use unrefined oils all the time?” and that’s a great question! The main reason is due to other factors such as flavour and stability.

Flavour

You also need to consider whether or not you want the chosen oil to add flavor to your meal. Refined vegetable oils tend to be milder in flavor and can therefor be used when trying to cook foods on high heats without imparting a strong flavor. Oils such as canola, sunflower and olive oil are all suitable options for meals involving cooking methods such as frying, sautéing and grilling.

Unrefined oils tend to have stronger flavours and are typically better choices when not using high heat cooking methods such as on salads, in dressings and with breads. This also allows us to get the full health benefits of these oils.

Other oils have particular flavours that make them ideal for specific cuisines. For example, peanut or sesame oil are great for Asian dishes and coconut oil is perfect if Pete Evans shows up on your door step with his paleo posse. (You don’t have any coconut oil? Don’t stress. He probably brought his own).

Stability

When choosing a cooking fat or oil, it’s important to consider the oil’s stability; how it holds up to temperature, aka its ‘smoke point’. An oil’s smoke point is the temperature at which the oil begins to create smoke and break down.

Heating oil to this point changes its chemical structure and destroys most of the beneficial health compounds.

The stability of oils varies depending on a number of factors. Refined oils tend to have higher stability and thereby higher smoke points. Oils with high levels of unsaturated fatty acids tend to have lower heat stability and therefor lower smoke points.

Due to this, it makes sense to use refined oils such as plain olive oil, canola oil and sunflower oil when cooking at high heats.

Health Benefits

Oils contain a number of beneficial compounds and nutrients. Vegetable oils may contain fat-soluble vitamins including vitamin E and vitamin K. They also contain varying amounts of beneficial bioactive compounds, such as the antioxidant polyphenols in virgin and extra virgin olive oil. Unrefined plant oils are also a natural source of sterols, which are preferentially absorbed by the human body, in place of dietary cholesterol (thereby blocking its absorption).[2] So unrefined vegetable oils can be beneficial for cholesterol management and cardiovascular health.

In the past decade saturated fats have been the hot topic due to their effects on cardiovascular health. Without adding an extra 2000+ words to the article the research seems to indicate that saturated fats aren’t the root of all evil. A number of reviews and meta analysis’ have found little concrete evidence to suggest that saturated fat increases the risk of cardiovascular diseases. [3] However, there is data to suggest that replacing some of your saturated fat with polyunsaturated and monounsaturated fats may reduce your risk. [4]

Storing Oils

If you’re like me then you may have a bottle of some fancy oil (truffle oil comes to mind) hiding in the back of your cupboard waiting for some special occasion that never comes.

Don’t.

Unlike wine or Jennifer Aniston, oils do not get better with time. Oils can in fact go ‘off’ or rancid. As mentioned previously, an oil’s chemical structure can change under different conditions. When exposed to light, heat or air, oils begin to oxidise, which results in flavour and colour changes as well as the breakdown of many healthy bioactive compounds.

One of the benefits of refined oils are that they have a longer shelf life. Saturated fats also tend to be more stable than unsaturated fats, and are less susceptible to oxidation.

Your best bet (especially with unrefined, more expensive oils) is to buy them as local and fresh as possible, store them in a dark, cool area and purchase smaller quantities so they are not sitting in your cupboard for long periods of time.

Practical Applications

Rather then go through each and every oil, I’ve created this nifty graphic below which gives you an overview of commonly used oils, their predominant fats, their characteristics and what cooking style or dishes they are best used for.

Choosing a Cooking Oil

 

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References:

1. Foster R, Williamson CS, Lunn J. BRIEFING PAPER: Culinary oils and their health effects. Nutrition Bulletin. 2009 Mar 1;34(1):4-7.

2. Lagarda MJ, García-Llatas G, Farré R. Analysis of phytosterols in foods. Journal of pharmaceutical and biomedical analysis. 2006 Aug 28;41(5):1486-96.

3. Siri-Tarino PW, et al Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease . Am J Clin Nutr. (2010)

4. Mozaffarian D, Micha R, Wallace S Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials . PLoS Med. (2010)