Preventing Your Best Olive Oil From Going Off

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Updated August 20th 2021

Preventing Olive Oil Going Off
Preventing Best Olive Oil Going Off

There is no point in finding the best extra virgin olive oil(EVOO) in the UK if you do not look after it properly.

That is why we have put together these tips on how to prevent your olive oil from expiring, so its quality, taste and benefits remain good for as long as possible.

Keep EVOO Away From Light

Many people are tempted to store their bottles of EVOO on the windowsill, so they are in easy reach when you need to use them for cooking. However, celebrity chef James Martin told TV viewers this is the worst place to keep EVOO.

Speaking on This Morning last week, the former Saturday Kitchen host spoke to Phillip Schofield and Holly Willoughby about storing extra virgin olive oil, Metro reported.

“Don’t put EVOO on the windowsill, because it will go off,” Martin said, adding: “Oil is light sensitive, so [put it in a] dark cupboard or away from that windowsill.”

Indeed, storing EVOO in a cool, dark place is the best way to maintain its shelf life. However, you do not necessarily need to put EVOO in a refrigerator, unless you do not have a pantry or cupboard that is suitable for it.

An article on Healthline advised those who do keep it in the fridge that it is normal if it looks cloudy, as “this is a normal reaction to cooler temperatures and does not indicate that your extra virgin olive oil has gone off”.

It is also worth buying bottles made out of dark materials, such as Morocco Gold Extra Virgin olive oil as this prevents light entering the container.

Close the cap properly

It is not just light that can cause your EVOO to deteriorate faster than it should, but exposure to oxygen too.

This can enable fat molecules to break down faster so  to prevent oxidation, make sure the cap is closed on the bottle properly.

EVOO : The Natural Ageing Process

Superior EVOO like Morocco Gold is obtained only when harvest, milling and processing of olives are properly managed. Along those steps, there are two naturally occurring and interrelated processes that must be understood as they impact EVOO’s quality: lipolysis and oxidation. Lipolysis (a form of hydrolysis) begins on the olive fruit as it ripens, and is caused by enzymes present in the fruit, which are later on removed with the vegetation water. Lipolytic enzymes break down major EVOO components and generate free fatty acids, precursors to EVOO change of condition.

Oxidation (more specifically, auto-oxidation) is triggered when the oil enters in contact with oxygen in the air, first during the milling process, and later on during storage in tanks and bottles. Oxidation produces peroxides from some fatty acids. Peroxides are unstable compounds which are further oxidized to yield volatile and non-volatile components that give rise to off-flavours and undesirable aromas in the oil (secondary oxidation). The other form of oxidation, photo oxidation, is usually minor and negligible if the oil is stored in the dark. In brief: lipolysis generates free fatty acids and oxidation causes the formation of peroxides from these fatty acids (primary oxidation), eventually leading to rancidity and degradation of the oil over time (secondary oxidation).

Attaining EVOO of superior quality requires minimizing the generation of free fatty acids by hydrolysis and delaying the onset of oxidation. The oxidation process in EVOO takes place in three stages: initiation, propagation and termination. 

EVOO Oxidation

Olive Oil Oxidation
Olive Oil Oxidation

The figure shows how the oxidation of fatty acids in olive oil changes with time. Once the oil has been decanted or centrifuged, the free fatty acid level (or free acidity) will gradually decline while the oil remains in storage. [Declining free acidity is represented in the graph by the down-sloping line from upper-left to lower-right.] During the initiation stage, free fatty acids present in the oil become slowly oxidized, giving rise to small amounts of peroxides. Since peroxides, in turn, decompose into other substances, the overall peroxide level does not increase rapidly. However, when certain levels of peroxides are reached in the oil, a propagation stage ensues during which peroxide levels will rapidly increase, as peroxides beget other peroxides. [Increasing accumulation of peroxides is represented in the graph by the rising left-side of the curve.] During the termination stage, peroxides further decompose giving off numerous off-flavour compounds that humans can detect, even if present at extremely low concentrations—below parts per million. Therefore, even when just a tiny fraction of peroxides degrade into undesirable compounds, the oil will begin to taste rancid. [Rancidity is represented by the lower line rising from the bottom-left to the right of the graph.] 

How We Preserve Morocco Gold EVOO

We take great care to ensure the longevity of Morocco Gold extra virgin olive oil, including the selection, early harvesting of our olives, carefully controlled handling and pressing of our olives, and the specialist nature of our glass bottle. This has been designed with a darker tone of green and thicker glass wall to maximise protection from UV rays that can interact with and alter foodstuffs. All these factors mean that our extra virgin olive oil, if stored in cool conditions, will have an extended shelf life.

Source: Healthline / Metro