Why Does Pesto Turn Dark?
Understand basil oxidation, heat and bruising so pesto stays greener, plus practical advice for a batch that has already darkened.
Dark pesto is usually safe if it was handled and stored properly, but colour cannot be reversed. Stir, taste and cover the surface with a thin layer of olive oil.
What went wrong?
Warm equipment heated the basil.
The surface was exposed to air.
Pesto was cooked directly in a hot pan.
Why it happened
Cut basil cells react with oxygen. Heat and prolonged processing speed the browning reactions.
What you can do now
- Judge freshness by smell and storage, not colour alone.
- Add fresh chopped basil only if it suits the dish.
- Keep the remaining pesto cold and covered.
How to prevent it next time
- Chill processor parts and pulse briefly.
- Dry basil thoroughly after washing.
- Loosen pesto in a serving bowl, away from direct heat.
Try it in context