From starch to sugar, at a careful temperature

The optimum conditions for ripening bananas, says CTAHR, are temperatures of 68 to 70 degrees F and 90% relative humidity. [CTAHR] During ripening, CTAHR says pulp temperatures should range from 58 to 64 degrees F. [CTAHR] As the fruit ripens, sugar content increases while starch content decreases. [CTAHR]

Two yellow bananas lying on a pale towel, with remaining green patches on the peel, especially near the stalks and along one side — Two Cavendish bananas mid-ripening, photographed on 20 October 2025: the peels are mostly yellow, with patches of green still visible. This is not a complete seven-stage chart, just a pair of fruit in the middle of the colour change.Sciencia58 · CC0

Ethylene gas can be applied to bananas to start the ripening process and to assure evenness of ripening, and bananas also produce ethylene gas naturally. [CTAHR] Neither green nor ripe bananas should be stored at temperatures lower than 58 degrees F; the fruit will discolor and the flesh will become mealy at cooler temperatures. [CTAHR]

A cold cupboard is not a ripening room

CTAHR’s storage floor is 58 °F. Below that, the peel discolors and the flesh becomes mealy. That is a different problem from leaving a ripe banana on a warm counter.

From starch to sugar, at a careful temperature

A cold cupboard is not a ripening room

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