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Freshly-pressed Omega oils are health-giving nectars, but when oxidised/rancid these oils are toxic and
should never be taken. What causes rancidity and what needs to be done to ensure that Omega oils meet international health and safety standards? Bruce Cohen explores the issue.

There is justified concern among consumers over the quality of Omega oils. Recent tests in the USA on fish oils have shown large variations in quality, with some leading suppliers accused of producing health-damaging rancid oils. With the increasing popularity of Omega-oils for treating health issues ranging from ADHD to heart disease, cancer and obesity, the market has been inundated with Omega products; now, more than ever, vigilance is needed in the choice of Omega oils to ensure consumers are getting health-giving supplements.

It is important to understand what rancidity is and how it is caused. Once the oil is released from its shell/fruit/nut (in the case of plant oils) or through the harvesting of marine life (fish oils), it begins to oxidise through contact with oxygen in the air. Heat and light accelerate the process of oxidation which ultimately leads to rancidity.

Oxygen is essential to life, but it is a double-edged sword becuase the process of oxidation is the prime cause of free radical activity. Free radicals are unpaired electrons inside oil molecules. Electrons prefer to travel in pairs but if they become "orphaned" from their partner they immediately look for another partner. The orphaned electron then "steals" an electron from another molecule creating a new orphan and so it goes on, triggering a cascade of free radical activity. Cancer is believed to be caused by free radical damage to DNA which results in cell mutation and uncontrolled tumour growth. Aging is a result of the accumulation of free radical damage to the body over time.

A good example of the oxidation process is rusting metal; slowly but surely oxygen in the air eats away at the underlying metal, causing it to break down. Ageing is really human rusting! Another example of rancidity is the smell of rotting fish - the stink is the result of the fish oil oxidising. In plant oils rancidity is less gross, usually detected by a burning sensation at the back of one's throat after consuming the oil. Bitterness can be - but is by no means always - an indication of rancidity. Proof of rancidity has to come from lab tests.

So consuming oxidised, rancid oils can be highly detrimental to one's health. Unlike many other foods which simply lose their nutrient value through oxidation, in the case of oils the result is a toxic product. It cannot be stressed enough how important it is to consume only fresh, un-oxidised oils.

NOTE: Not all oils oxidise at the same speed. Oils containing Omega-3s (e.g. salmon and flax) are most prone to rapid oxidation; olive oil (Omega-9) is more stable and will oxidise at a slower rate. Coconut oil and animal fats (saturated oils) are very stable. Many plant oils (e.g. sunflower) are naturally rich in anti-oxidants which protect them from rapid oxidation.

How do we ensure oil freshness and quality which unlocks the health benefits of the oils, and restrict the free radicals that result from oxidation?

At Absolute Organix, we believe the answer lies in the three Ps - Pressing, Preservation and Packaging/storage.


True, cold-pressed plant oils (pressed at below 40C, which is the European standard) enable us to produce high quality oil without heat. As mentioned above, heat accelerates oxidation and rancidity, so keeping the oil cool right from the pressing stage limits oxidative damage. At Absolute Organix, our oil press is monitored throughout the day to ensure we stay below the 40C limit. Once the press starts running, lights are switched off so pressing takes place in the dark because light, too, accelerates the oxidation/rancidity process.

Oils produced industrially involve the use of solvents such as hexane and high temperature refining. So there is a huge difference in oil quality between cold-pressed and chemically extracted oils.

At Absolute Organix we only produce extra virgin oil - this means that the seed is pressed once. Some companies feed the "seed cake" residue back into their presses to extract more oil, but in our view this reduces the oil quality and increases the risk of oxidation because the seed cake is typically expelled at much high temperatures than the virgin oil.

After the oil has been pressed, it needs a few days to settle out the sediment. At Absolute Organix settling takes place in a cold-room away from light. We then filter the oil using a heat-free centrifuge process which spins out the remaining sediments, resulting in golden, clear virgin oil.


In order to protect the delicate Omega fatty acids from oxidation and ensure freshness, small amounts of anti-oxidant are usually added before bottling. We have tested a number of anti-oxidants (such as Vitamin E and Alpha Lipoic Acid), and have selected natural rosemary extract as our anti-oxidant/preservative of choice. Rosemary extract has been scientifically validated as a powerful anti-oxidant that is especially effective with plant oils.


At Absolute Organix, the challenges posed by heat, light and oxygen in the bottling of our oils is addressed as follows:

1)   We bottle only in glass which is totally inert and prevents any oxygen entering through the walls of the bottles. We have never used plastic bottles because of concerns over the leaching of chemicals from the plastic into the oils.

2)   We only use opaque, frosted, amber glass bottles to ensure zero light penetration.

3)   After the oil has been bottled, we bubble nitrogen through it. This displaces any oxygen that may have been trapped in the oil and also creates a "blanket", preventing any oxygen left in the airspace at the top of the bottle from coming into contact with the oil below.

The bottled oils are immediately returned to the cold room where they remain under refrigeration until delivery.

Our philosophy has been always to press small quantities of oil daily rather than large batches that have to be stored. That way we are able to provide just-in-time deliveries of fresh oil that does not require long-term storage.


All this effort in producing fresh, health-giving oils would, in our view, be wasted if the seed was not organic. We only use certified organic seed, produced without pesticides and synthetic fertilizers. Our current flax suppliers are in the Ukraine (no flax seed is grown in SA), which produces an excellent oil-rich seed that is guaranteed GMO-free. Before the seed is shipped it is fumigated naturally in a carbon dioxide-filled chamber to ensure no pest contamination (this process is approved for organic certification)


Doing all the right stuff does not always guarantee that the final product delivers the expected result. It has to be proven independently through testing.

As oil oxidises, a chemical by-product is the creation of peroxides. By measuring the peroxide content of the oil, one can determine the degree of oxidation. This is known as the PV (Peroxide Value) and there are laboratory tests for it. However, oxidation is not linear, it occurs in cycles - an initial or primary cycle, followed by secondary oxidation cycles). In the gaps between the cycles, the PV actually drops, so one has to be careful about when one tests the oil or one may get very misleading results e.g. analysing the PV of oil at the end of a cycle will result in a low PV when in fact the oxidation process is already well underway.

The only way to accurately measure oxidation/PV is to do so over time, taking readings at regular intervals. A further test, called an Anisidine test, tracks the oxidation cycles in effect providing an "audit trail" of oxidation. So you need to do both tests to get an accurate picture of the oil.

It is generally accepted that nutritional oils with a PV above 10 is totally oxidised/rancid and is unfit for human consumption. This is the standard set by the EU Codex.

However, a much more stringent but voluntary standard set by the Council for Responsible Nutrition (CRN) in the USA sets a PV maximum of 5. This standard is applied primarily to fish oils where the long-chain fats (DHA and EPA) are especially delicate and prone to rapid rancidity because, unlike plant oils, they have no natural anti-oxidants present to protect the Omegas.

At Absolute Organix we believe the PV 5 limit should apply to any Omega-rich oil (plant or marine) and we use it as our benchmark.

During the period November 2009 to January 2010 we employed the services of an independent specialist laboratory (FIRI Consulting in Cape Town) to analyse the quality of our organic flax seed oil by running a series of PV and Anisidine tests. The test will continue for some months, but the results we now have give a clear indication of our oil quality/freshness.

The test protocol involved storing the oil at an ambient temperature of 20C. This is more than three times higher than the refrigeration temp (approx 5C) at which our oils are typically stored on our premises or in the fridges at retail outlets. It's what's called "accelerated" shelf-life testing: 3 months at 20C equates to 9 months at fridge temp (5C). Our aim was to validate the 9-month shelf-life/expiry date we give to our oils and to offer our customers independent proof of our oil quality.

The results are summarised in the chart on the right, which compares the actual Peroxide Values of our oil (the red bars), taken at 30 day intervals over3 months, with the two standards (Codex and CRN).

You will see that the PVs of our oil are significantly below the Codex and CRN limits (never in fact exceeding a PV of 2). The Anisidine tests done simultaneously showed a zero result (although you can see the winding down of the primary oxidation cycle in the graph).

Based on these results, the measures we are taking to produce fresh, un-oxidised oil appear to be paying off, preventing the emergence of any significant oxidation cycles which would lead to our oil becoming rancid within 9 months (Eventually, all oils will go rancid - our primary objective is to ensure this does not happen within the expiry period).

Footnote: One further issue to consider is that of encapsulation. Once oil has been encapsulated, any rancid taste will be masked, and unless you actually bite into a capsule and taste the oil (especially fish oils) you are unlikely to recognise rancidity. If it stinks like rotting fish, best feed it to your dustbin and choose another supplier!

One tell-tale sign of potential rancidity can occur a short time after swallowing a capsule - those icky repeating burps start bubbling up from your tummy.
Written by: Bruce Cohen of Absolute Organix.
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