Sunlight beats baking soda and peroxide for plastic stains.

Sunlight is the safest and most effective way to fade curry and tomato stains from plastic lunch containers.

Tomato and curry stains are pigments (lycopene, turmeric) that soak into microscopic pores in the plastic. Baking soda is a mild abrasive — it helps scrub surface gunk, but it can’t reach the color that’s already inside the plastic. Hydrogen peroxide does break down pigments and will whiten the stain, but it’s an oxidizer and can slowly make food-grade plastic brittle over time, especially with repeated soaking.

The sunlight method is dead simple: wash the container, leave it slightly wet, and set it in direct sun for a few hours. UV light breaks the pigment bonds naturally, no chemicals, no scrubbing. It’s not instant — often a day or two of sun sessions for old stains — but it’s the only method that’s both safe for the plastic and actually removes the color. For extra help on stubborn spots, a thin paste of baking soda and water as a gentle scrub before the sun does no harm, just don’t expect the baking soda to do the heavy lifting.

If you’re in a hurry, peroxide at 3% food-grade strength for 15–20 minutes works, then rinse extremely well. But for daily lunchbox wear and tear, let the sun do its thing.

Your plastic will last longer without the chemical treatments.