A fruit, slowly
Pull the slider and watch one gas rewrite the fruit — from hard and green to soft, sweet, and red.
Stored starch breaks down — the flesh tastes sweet.
Chlorophyll degrades, letting warm pigments show.
The glue between cells weakens — firm goes soft.
Tart organic acids get used up — sharpness eases.
The engine
Ethylene is a plant hormone. A trace of it switches on the genes that produce more ethylene — a loop that feeds itself. That's why ripening speeds up once it starts, and why a single ripe apple hurries along every fruit in the bowl.
Cold air suppresses ethylene production. The fridge buys a ripe apple days, sometimes weeks.
A paper bag traps the gas around the fruit. Add a banana and it ripens faster still.
Keep apples away from greens and herbs — the same gas wilts and yellows them early.