Processbeginnerdraft
Enzymatic browning
Also searched as: apple turns brown, brown avocado, potato turns brown, discolouring
In short: Cut apples, potatoes or avocados turn brown because an reacts with the oxygen in the air.
Picture it
Like rust on a fresh cut: where the skin is missing, air gets in.
Level 2 · Cut surface of an apple≈ 1 mm
Simplified model
What happens
Cutting opens up cells. An enzyme and colourless substances from the cell meet oxygen and form brown pigments. slows the enzyme, cold slows it down, heat destroys it and water keeps the air away.
Why it matters
Explains why lemon juice belongs on the apple and why raw potatoes should sit in water.
Rules of thumb
- Drizzle with lemon juice.
- Put cut potatoes in water.
- A quick stops browning for good.
Levers
2
pH (acidic to alkaline)acidic → slows it
Temperaturecold → slower, hot → stops it
Related entries
Sources · 1
- Harold McGee: On Food and Cooking (2004), Kapitel Gemüse, Eier