Garum
Experimentbeginnerdraft

Acid cooks fish without heat

Also searched as: ceviche experiment, fish in lime juice

In short: Raw fish cubes in lemon or lime juice turn white and firm within half an hour, as if cooked.

Picture it

Like egg white in a hot pan, but without the pan: the acid does the work of the heat.

Before · Afterraw
in lemon juice
in water
Schematic
You need · 30 minutes
  • a piece of very fresh white fish
  • lemon or lime juice
  • water
  • two small bowls

Only with very fresh fish; for children, for looking at only. Do not eat it if you are unsure how fresh it is.

How it’s done

Sequence · Step 1 of 3
123

Cut the fish into small cubes.

All steps as a list
  1. Cut the fish into small cubes.
  2. Cover one half with lemon juice and the other with water.
  3. Cover and chill for 30 minutes, then compare.

What you see

In the juice the fish is white and firm on the outside; in the water it has stayed translucent and soft.

Why it happens

Acid changes the proteins much as heat does: they unfold and link up anew. That is why the fish looks cooked. But acid does not kill germs as reliably as heat.

Related entries
Acid cooks proteinProteins change (denaturation)Fish and seafood
Sources · 1
  • Harold McGee: On Food and Cooking (2004), Kapitel Fisch: Ceviche