The three enemies: light, air, heat
Three factors degrade extra virgin olive oil through oxidation, producing rancidity (the acrid smell and stale taste of old oil):
- Light: UV rays oxidise pigments (chlorophyll) and polyphenols. A few weeks of direct sunlight is enough.
- Air (oxygen): the main driver of degradation. Every time you open the cap, some oil oxidises.
- Heat: above 20°C (68°F) all degradation processes accelerate noticeably. Kitchen counter, near stove or oven: wrong places.
The right container
For retail, quality oil is sold in:
- Dark glass bottles (green, amber): filter some UV
- Metal tins: the best for medium quantities (1-5 litres / 33-170 fl oz)
- Bag-in-box: excellent for large quantities — oil never meets air until the last drop
Avoid: clear plastic bottles, non-airtight containers, clear glass bottles left in light.
Where to keep it at home
- Closed pantry or cellar: the best spot (12-18°C / 54-65°F, no light)
- Never on the kitchen counter: too warm + too much light
- Never near the stove or oven
- Not in the fridge: oil crystallises (turns white and grainy). Not harmful, but you'll need to wait for it to liquefy again.
- Always cap it tight after use. Dosing caps that stay open: convenient, but they shorten shelf life dramatically.
How long it lasts: sealed vs opened
Sealed: 18-24 months from bottling. High-polyphenol oils (Ortice, Coratina, Picual) can keep their character even longer.
Opened: 3-4 months for full aromas and antioxidant power. Still usable longer, but flavour fades.
Practical tips: buy bottle sizes that match your consumption; for low usage, choose 250-500 ml tins; never transfer oil into clear tabletop carafes.