Flax: is Refrigeration essential?

Q: Is Refrigeration for linseed (flaxseed) oil essential?

A: No Linseed does not have to be kept in the fridge

We believe we supply the best cold-pressed linseed oil ( otherwise known as flaxseed oil) in the UK; we make and bottle the oil by cold-pressing the seeds using the coolest, gentlest methods.  It is designed to be used fresh as a fresh food and is not intended for long storage.  We send it out absolutely fresh, within a few days of pressing.   We recommend that the oil we send out is consumed quickly as a fresh oil to enjoy it’s flavour and nutritional benefits at their best.  Like all produce linseed (flax) does deteriorate over time. However as oil is very different to meat, milk or vegetables  and we are not trying to control spoilage by bacteria or moulds refrigeration has less significance to ensuring the freshness and quality of oil.

Linseed oil, as food and therapeutic oil, has been pressed on small presses for centuries and likes to be produced on a small scale in a traditional way, a bit like home cooking – just as food like omelettes are much better when made at home than mass-produced in industrial kitchens and your granny’s sponge cakes we great on the weekend they cooked but went stale after that – next time you are in a supermarket check-out all the weird ingredients that go into long life packaged cakes and taste them; nothing like my granny’s cakes!

When linseed/ flax oil is produced on a larger scale in a more industrial way, usually with  higher temperatures, higher pressures and more machine/chemical processes are involved.   Linseed doesn’t respond well to this sort of treatment and it often makes it start to go rancid and bitter at the point of manufacture, this then goes off like dominoes toppling and the rancidity gets worse and the oil more bitter;  refrigerating the oil helps slow this effect down a little – but it is a bit like shutting the stable door after the horse has bolted when oil is rancid to start with.  It is of significance as many of the mass-produced linseed/flax oils are expected to be in shops for many months, even up to two years, refrigeration means it gets worse slower!  It doesn’t make up for it not being fresh, Flax Farm linseed oil uses varieties of linseed that make nice tasting linseed oil, it is then supplied fresh and used fresh – we like it to be used within 2.5 months of opening or 4 months of pressing. Even at the end of this time Flax Farm cold-pressed linseed oil still tastes great.  Good Linseed (flax seed) oil should be mild, creamy, nutty, grassy, I.e. characteristically taste of linseed (flaxseed), with no off or rancid butter notes.  Linseed (flax seed) Oil should not be bitter or smell strongly.

Cold-pressed linseed/flax oil is very different to milk

Storage of oils like linseed /flax seed oil is very different to something like milk.  Milk goes “off” due to enzyme activity because of microbes getting into it and multiplying. Keeping it below 4 degrees centigrade helps to stop the dangerous ones establishing themselves as and once warmed for a short while the population of microbes is becomes huge and the milk then starts to go off very quickly, it can even go “off” in less than one day .

However linseed/flaxseed oil is completely different; this is nothing to do with microbes.  Linseed oil/flax seed oil is very rich in omega-3, this is a delicate and reactive molecule which is why it is so good for us (it means the body’s systems can link it easily to other nutrient molecules to make it into body components like cell membranes and hormones) unfortunately it also means it can oxidise if not properly cared for.  Oxidation is slowed down by cooler temperatures but as the difference between ambient temperature and refrigeration temperature is only 16 degrees this isn’t very significant (as temperature of all things starts from minus 273o Celsius and goes up to many thousands of degrees) so even as much as a few weeks at ambient temperature doesn’t really have much effect on the oil; it simply shortens the time it takes to lose its optimum freshness by, at the most, no more than a few days.   Which is why it is not critical to keep it refrigerated and it doesn’t spoil the quality.  It continues to be nice and just as good for you as linseed oil has ever been – and bear in mind linseed oil has been used as a “health food” for thousands of years before refrigeration was available.   This means that the few days between pressing and receipt of the oil makes effectively no difference to the flavour, quality or effectiveness of the oil.

Properly produced Linseed oil is actually far m heat stable than it is given credit for.  We have tested it extensively.   However it is very sensitive to strong light. Left in strong sunlight linseed oil (flax seed oil) can go rancid and bitter in less than an hour. So always avoid it being left in direct light store it in the dark.

We have many enthusiastic users of the oil who never put it in the fridge, they consume it fresh  and it remains fresh lovely and with all its health benefits.

The fridge is the best place to store linseed

However, just as the fridge or freezer is the best place for freshly ground coffee the low temperature keeps opened linseed (flax) oil a bit fresher for a bit longer. We also recommend if you are buying in bulk you store in the freezer  as the best place to store your linseed oil.   Being that freezers and fridges are dark this is an additional benefit to keeping linseed, oil or ground linseed fresh.

If you don’t have room in your fridge or freezer to store your the oil, don’t worry as long as you consume it bore the best before date it will be fine.

The Flax Council of Canada is really the World authority on flax (linseed) and their primer  is an excellent source of information for all things flax/linseed.   Go to the Flax Council Primer, appendix B for information on storage and heat-stability