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Is our thirst for cold pressed vegetable oils costing the planet?

July 20, 2019

When it comes to vegetable oils, there are two types of people I talk to, those without a prior opinion and those with one. Those with an opinion most often feel that the less processing or the gentler the processing a vegetable oil has gone through, the better it is.  I can understand the logic of that, less and more gentle processing retains more oily ‘goodness’  but what if the goodness never got out of the plant in the first place? What if we just threw half of the oil away?

I was looking into Castor Oil for a client of mine recently and I came across a paper that stated mechanical pressing would only achieve a 45% yield of the oil from the seed.  To put that another way, just ‘cold pressing’ leaves 55% of oil still in the plant.  Thinking on, that means for every 1 litre of cold pressed castor oil that makes its way onto the shelf, 1.222 litres of oil is potentially thrown away.  I’m not sure that sounds so environmentally friendly now.

After reading that about Castor Oil I wanted to look into another popular cosmetic oil, Rose Hip.  This study evaluated five high-tech extraction mechanisms including different types of CO2 extraction, solvent extraction, microwave and ultrasonic water bath.  Yields from the seeds ranged from 3.25% (water bath) to 6.68% (Subcritical CO2).  Meanwhile this study compared conventional cold pressed vs supercritical Co2 extraction and solvent (hexane) extraction.  Here we see yields of 6.5% for the supercritical Co2,  cold process 5% yield and the hexane oil was in-between but of worse quality.   Even though these two studies are not directly comparable (different rose hip species) the pattern in extraction results marries up.  Rose Hips contain somewhere between 6.5-7% oil as a general rule so if we take the maximum oil concentration as 7, the supercritical Co2 process extracted just under 93% while the cold pressed method only extracted 71.5% or, to put it another way, 28.5% of the oil was left behind with cold pressing vs only 7% of oil with CO2 extraction. Information on typical oil yield and compositional information is here.

Now I get that the quality of oil is important, it’s no use having a lot of rubbish. However, if the oil doesn’t come out at all, it is worth nothing as it is thrown away.  I think in this day and age when we are so worried about land use, the environment, conservation and sustainability we should take all of the science available to us into consideration.   It is likely that the optimal extraction method will differ for each oil and that’s difficult as it means that brand owners wanting to be sustainable will have to research each oil (or talk to someone who can do that for them). While that is a lot of work, it should be worth it as I’m sure none of us want to see our precious oils go to waste.

I hope you can consider the points raised here when you are making your enquiries and investigations into ingredients.  Remember we have to work as a team here and is nobody thinks, nothing gets better.

Amanda x


3 Comments leave one →
  1. October 18, 2019 2:27 pm

    You’re a minefield if info – love your blog

    • RealizeBeautyEd permalink*
      November 19, 2019 6:53 pm

      Thank you! I try to put everything I have at the time into each post.

      • November 19, 2019 8:05 pm

        I do the same – I believe it’s the only way to go and the ones that do – stand out.

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