system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do plastic containers become orange-stained when they come in contact with hot tomato sauce?
gpt
Tomatoes contain a lot of lycopene, a bright orange substance that stains. The lycopene sticks very well to the plastic, causing it to stain. A little bleach and water can help oxidise and remove the stain.