It is important to understand what rancidity is and how it is caused. Once the oil is extracted 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.
Oxidation, an entirely natural process vital to life, is a double-edged sword because it causes free radical activity in the oil. Free radicals are unpaired electrons inside the oil molecules. Electrons prefer to travel in pairs but if they become “orphaned” from their partner they immediately look for another. 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. Ageing is a result of the accumulation of free radical damage to the body over time.
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.
(NOTE: Not all oils oxidise at the same speed. Oils rich in 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. Some plant oils (e.g. sunflower and grapeseed) are naturally rich in anti-oxidants which protect them from rapid oxidation/rancity.
How do we ensure oil freshness and quality, which unlocks the health benefits of the oils, and prevents 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) produces 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 pressing temp is monitored throughout the day to ensure we stay within the 40C limit. And once the press starts running, lights are switched off so pressing takes place in the dark because light, too, accelerates oxidation.
Oils produced industrially involve the use of solvents such as hexane followed by further chemical refining. These processes strip all nutrients from the oils, leaving behind shelf-stable oily “substances” that look like oil but can hardly be classified as a food/nutrient.
So there is a big difference in oil quality between cold-pressed and chemically extracted and processed oils. (The worst of these are margarines which have been (partially) hydrogenated which results in health-damaging plastic-like fats called trans-fats.
But back to the good stuff.
At Absolute Organix we specialise in organic flax seed oil which is the basis of the various blends we produce : Omega 369, Omega Slim, Omega Sport, plus of course our “vanilla” organic flax seed oil. We only produce extra-virgin oil; 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. We setlle our oil in stainless steel tanks 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 a golden, clear, virgin oil.
In order to protect the delicate Omega fatty acids from oxidation and to 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 for esxtended periods. That way we are able to provide just-in-time deliveries of fresh oil.
ORGANIC vs NON-ORGANIC
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). We choose to press seed that is 99,9% pure, the highest standard of seed quality.
DOING THE TESTS
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 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 quality.
It is generally accepted that nutritional oil with a PV above 10 is totally oxidised/rancid and is unfit for human consumption. This is the limit set by the EU Codex, the regulatory framework for complementary health products.
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 oxidation because, unlike plant oils, they have no natural anti-oxidants present to protect the Omegas.
We believe the PV 5 limit should apply to any Omega-rich oil (plant or marine) and we use it as our benchmark.
In the last quarter of 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 already 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 roughly 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 customers independent proof of our oil quality.
The results are summarised in the chart here, which compares the actual Peroxide Values (PVs) of our oil (the red bars), taken at 30 day intervals over 3 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 – when those yukky, repeating burps start bubbling up from your tummy.