Processbeginnerdraft
Fat goes rancid (oxidation)
Also searched as: rancid, stale-smelling oil, rancid nuts
In short: Oxygen, light and heat break fats down over time into unpleasant-smelling substances.
Picture it
Like rust on metal, only with fat.
Level 3 · Fat in the storage bottle≈ 1 nm
Simplified model
What happens
Unsaturated fats, as found in nuts, wholemeal flour and many oils, react slowly with oxygen. Light and heat speed this up. Substances form that smell of paint or cardboard.
Why it matters
Explains why nuts, wholemeal flour and linseed oil should be stored somewhere cool and dark.
Where you meet it
Rules of thumb
- Store oils cool and dark.
- Buy nuts and wholemeal flour in moderation, or freeze them.
- Go by smell rather than by date.
Levers
2
Temperaturecooler → slower
Timelonger → more rancid
Sources · 1
- Harold McGee: On Food and Cooking (2004)