Comments 2


The most important thing to remember about vegetable oils is that they are unstable and far more prone to turning rancid when exposed to oxygen, light – far more so than saturated animal fats. For this reason liquid vegetable oils should always be stored in dark bottles, away from sunlight in a cool spot and are best consumed unheated in salad dressings or mayonnaise-style sauces as they traditionally always were. Vegetable oils are best used for gentle sautéing rather than high-heat frying because of their propensity to turn rancid.

One key distinguishing feature between traditional vegetable oils and fake, new vegetable oils is that the former derive from the fruit of the plant (such as the olive or the coconut) whilst the latter derives from the seeds of the plant (such as sunflower-seed, rape-seed, seeds of the soya-bean plant, cotton-seed, grape-seed). Most seed oils (though not all) are fake foods and are best avoided. (For a complete list of real food and the fakes see below).

Vegetable oils are referred to either as polyunsaturated or monounsaturated for the simple reason that they contain, as a percentage, more polyunsaturated and monounsaturated fats than animal fats, with the exception of coconut and palm oil both of which are highly saturated. Polyunsaturated and monounsaturated fats are liquid at room temperature. Saturated vegetable oils are solid at room temperature.

Most seed and nut oils, being hard to express, would rarely have formed a major part of the traditional European diet. The first expressed seed oil to become wide-spread in northern, eastern and central Europe was sunflower oil in the mid-nineteenth century following industrialisation. It is interesting to note that although sun-flowers derive from Mexico there was no tradition among the Mayan or Inca populations of expressing sunflower seeds to extract the oil for cooking.

The practice of expressing sun-flower oil became common-place following the invention of high-speed mills powered by fossil fuels and which were capable of expressing enough oil from the sunflower seeds. From there the practice of expressing sunflower oil spread to other parts of the world most notably Europe where by the mid-twentieth century it was used extensively in domestic kitchens and by the industrial cook as a cheap alternative to butter, lard or drippings for high-heat frying.

In the mid-twentieth century industry went one step further and began altering the genetic make-up of various plants the oils of which were hitherto considered too toxic for human consumption. Most notable amongst these are rape-seed oils (known as Canola in North America) and soya bean oils. In their natural state these plants contain toxins that the human body is unable to tolerate, which is probably why they never formed a part of traditional food and cooking. Although some of the toxic elements of these plants will have been removed thanks to contrived bio-engineering, the consumption of these new fake oils, as we will see, leads to other challenges for the digestive system.

In the case of rape-seed oil/canola this oil was never consumed in most European or North American countries for the simple reason people knew it to be toxic. In its natural state rape-seed oil contains large doses of erucic acid – a  long fatty chain humans are unable to digest.  In the 1960’s Canadian scientists managed to genetically modify the rape-seed plant so that modern varieties – although they look the same – do not contain the toxic erucic acid. The rape-seed which is now grown and harvested is thus a genetically modified plant that dates back no further than the 1960’s. Although modern plant varieties of rape no longer contain erucic acid they do have a disproportionately high level of omega-6 to omega-3 fats, are prone to turning rancid when extracted with high speed mills and are highly processed in order to remove bitter, unpalatable flavours.


  1. ‘Vegetable oil’ is an all encompassing term, like ‘coffee’, ‘tea’, ‘flower’, ‘tree’… Not that there are as many commercial vegetable oils as there are vegetables, there are nonetheless many vegetable oils to use for preparing food. Just like petroleum fractions, (petroleum is ancient vegetable and animal fat oil), one has to choose an oil by its temperature range stability (resistance before degradation) for the particular desired end (processing) application. Short and sweet, there are ‘cold’ oils used for salad dressings like sunflower oil and ‘hot’ oils for Wok cuisine (‘peanut’ oil) and deep frying French Fries (a host to mixture of corn, olive, etc, oils). The ‘hot’ oils have replaced since decades animal tallow based oils in commercial institutions and homes for deep frying where the oil is used at elevated temperatures (190 °C) for up to 10 to 12 times (cycles) in its pure form (no stabilizers) for lengthy heat histories (30 + minutes at a time). All vegetable oils should definitely be keep in the dark (away from UV degradation); however, high temperature exposure at quick peaks or over lengthy time intervals as mentioned do not lead to sudden spoilage (‘going rancid’) of the oil . All the same can be said of animal fats: butter will quickly burn whereas tallow is used for deep frying. Butter can sit on your kitchen counter top for weeks and won’t go rancid as long as it covered from light at room temperature and contaminants introduced from spreading knives are not abundant.

    Your site/blog here is wonderful and the energy you dedicate to it is fantastic! I would simply suggest you throw in the odd reference to support your work.

  2. Hi Ronald

    You raise some interesting points. First off – I’ve decided not to use references since this is not an academic work. It is written for the everyday cook to help them decide what ingredients to cook with.

    The purpose of this work is to help cooks distinguish between real food and fake food. In the case of fats and oils this requires us to understand the difference between the kind of fats and oils that most populations would have been able to cook with prior to the arrival of the industrial revolution and the invention of many new foods.

    Until the mid-nineteenth century there were very few populations that consumed vegetable oils to any large extent – bar those living in the tropics who has access to coconut oil and Mediterranean populations who had access to extra virgin, cold pressed olive oil. The rest consumed much smaller proportions of vegetable oils in the form of grains, nuts and fresh fish. Some populations in the middle east ate small amounts of sesame oil and some populations in central and eastern Europe had some access to linseed oil. However, since squeezing the oil out of nuts and seeds, without recourse to the power of fossil fuels, is a tricky exercise few populations engaged in this practice

    The vast majority would have consumed fats in the form of saturated animal fats – butter, beef and pork drippings, lard, tallow, suet, goose fat etc. You are right to suggest that butter is not good for deep fat frying because it has a high smoking point. This is because it contains the protein casein and the sugar lactose, which explains why butter was rarely used for deep fat frying in traditional European cooking. Instead, traditional non-Mediterranean populations, fried in beef drippings, lard or goose fat. Clarified butter, or ghee as it is commonly known, is an ancient method of removing many of the impurities in butter and is widely used in traditional Indian and Pakistani cooking. Because it has had all the impurities removed it is excellent for deep fat frying – but it is also quite expensive compared to other forms of cheaper animal fats.

    Many modern vegetable oils, such as sunflower, canola and soya oil have a high smoking point because they, like clarified butter, have had all impurities removed – but they are still highly problematic for a number of reasons. For a more in-depth understanding of the problem associated with modern vegetable oils you might be interested to read these posts.

    Traditional Vegetable Oils: https://masterinthekitchen.com/2014/12/11/traditional-vegetable-oils-real-food/
    Non-traditiona Vegetable Oils: https://masterinthekitchen.com/2014/12/11/non-traditional-vegetable-oils-the-fakes/

    I’d love to hear what you have to say.

    Hope this helps, K

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