The rapid increase in the variety of edible oils over the last decade can lead to confusion in the supermarket aisle. Some of these oils claim to be both healthy and good for cooking. The truth is the best pantries are stocked with several types of oil, as some are deemed healthy but are unsuitable for high heat cooking, whilst others are very stable under heat, but may not have all the attributes of the healthiest oils.
There are nutritional concerns about the effects of heat on polyunsaturated fatty acids so these highly unsaturated oils should not be used for repeated high heat cooking. Oils are divided into categories based on their differing fatty acid compositions, and this is a good place to start determining the best oil to use.
Saturated oils: meat and dairy based fats, palm oil, coconut oil
Monounsaturated oils: olive oil, avocado canola, nut oils
Polyunsaturated oils: soybean, safflower, sunflower, corn, hempseed, rice bran, flaxseed (omega-3)
At the most basic level, healthy oil is low in saturated fatty acid. Oil must contain less than 20% saturates to receive The Heart Foundation’s “Tick” as a healthier food choice.
Check your labels: less than 18.4 grams of saturated fat per 100mL quantity indicates a better choice. Other indicators of healthy culinary oils are high levels of monounsaturates or polyunsaturates, and the presence of natural antioxidants such as polyphenols or Vitamin E.
Additionally, there has been recent nutrition research indicating that out of the two types of polyunsaturated fatty acids, omega-3 and omega-6 we should be reducing our omega-6 intake and increasing omega-3. Oils such as soybean, sunflower and safflower are very high in omega-6. The next step is to determine which oil will be the best for your particular needs in the kitchen. The smoke point- an important factor in high heat cooking - is independent of the source of the oil, and therefore is not directly linked to the level of saturated fat in that oil.
From a chemical standpoint, the smoke point is directly related to the free acidity. Oils that are fully refined have low acidity and high smoke points. These oils are sometimes referred to as RBD (refined, bleached, and deodorized) and can include peanut, soybean, and canola, “light” olive oil, sunflower, rice bran, and safflower – with smoke points in the 230C-265C range. They are good candidates for cooking, but the additional processing removes some of the added nutritional benefits, so may not be the best for other uses. Locally available, high-quality unprocessed oils have varying smoke points, such as NZ extra virgin olive oil (190-200C), hazelnut oil (190-200 C), and avocado oil (230C). Imported olive oils tend to have poor flavours and high acidities and subsequent low smoke points around 170 C- this is the reason so many urban myths say that olive oil is unsuitable for shallow pan frying.
With this in mind, here are some suggestions to ensure you have a well-balanced selection of oils in your pantry:
1. Solely Nutritional oils: Flaxseed oil ,walnut and/or high quality fish oil (as dietary supplements rather than cooking ingredients)
2. High quality oil for dipping/ drizzling/salad dressings: NZ Extra Virgin Olive oil, hazelnut and avocado oils.
3. Stable and Economical for heat: RBD oils, refined ‘light’ olive oils, rice bran oils, avocado oils
Top tips for choosing your oils
• Search for oil in dark glass or cans, as clear glass or plastic bottles promotes oxidation (leading to rancid tastes)
• Buy from a shop that has a regular turnover of stock
• Buy in small quantities that meet your needs without lingering on your pantry shelf for too long – a great way to try the different products available to you
Note from Dan: I found the supermarket isle very confusing, especially with regards to Olive Oils; some say ‘light’, but that doesn’t mean low in calories! It just means refined. Laurence’s comment that imported olive oils are not as good as our own ones is particularly important. A little known fact is that the best olive oils are not generally exported from the Mediterranean countries. Olive oil is a major part of their diet, so they are particularly discerning … and they keep the best for themselves. We tend to get the second grade oils, you often find it in light coloured one litre bottles with fancy labels, but don’t be fooled. Oils in cans are likely to be of better quality than oils in light bottles, regardless of price, and as Laurence said, the best ones are home grown. Often, these home grown olive oils are in smaller dark bottles, they are less economical - but a great healthy choice for drizzling on salads.
Nutritional oils are often (but not always) sold in capsules as supplements, such as Lester’s Oil (containing a concentrated purified Omega-3 from fish oil) or flaxseed oil. Laurence also pointed out what I have said quite a bit on radio and in articles, that most of the research is on marine long chain Omega-3 fatty acids, not Omega-3 from plant sources! (Flaxseed oil). Omega-3 from plant sources likely confers health benefits in humans as well, but they are different to those from fish oil.
Stick with what the research says – its fish oil all the way! One more point is the fact that many plant oils contain Omega-6’s, the Western diet in general needs less of these, over consumption of Omega-6’s relative to Omega-3’s is an important risk factor for many diseases. On the nutrition side of things, Olive Oils and other good oils contain polyphenols which are very good for us! When it comes to frying, I managed to get a cheap pan to colossal temperatures in just a couple of minutes on a gas stove. I used a laser temperature gun to measure this. This is very bad for several reasons, when Teflon coated pans reach 260 degrees, the Teflon starts to break down and ‘off gas’. Six different gasses are eventually given off, and these gases can actually kill birds (so what do they do to us?). I recommend you get a good old cast iron frying pan. Once you cook with it a few times, it becomes almost like a non-stick pan (and they are pretty much indestructible). I do an omelette in mine several mornings a week. The smoke point is also relevant; again the quality of the oil as opposed to the exact type is very important. A high quality local extra virgin olive oil (higher smoke point) may well be just fine for shallow pan frying, while a more acidic low quality imported extra virgin olive oil (lower smoke point) may not be suitable. As Laurence points out, there are cheaper oils as well. So, the moral of the story is that you need to be wary of the ‘super-marketing’ of oils, the best ones may not be what you think. Those fancy European brands are likely the worst ones to use, and a good local extra virgin olive oil or avocado oil is a great choice for both salads and frying.
