• Question: How do fruits ripen? How do fruits ripen when they have been picked? Why do fruits get sweeter the riper they are?

    Asked by Zealousy to Chris, Josh, Rebecca on 25 Jun 2015.
    • Photo: Josh Meyers

      Josh Meyers answered on 25 Jun 2015:

      There are different types of fruit that ripen in different ways.

      Climacteric fruits carry on ripening after they are picked
      Non-climacteric fruits can ripen only on the plant and thus have a short shelf life after they are harvested.

      Bananas release ethylene gas which accelerates the ripening process. That is why they cause other fruit in the bowl to go off quicker

    • Photo: Rebecca Dewey

      Rebecca Dewey answered on 25 Jun 2015:

      When fruits ripen, the flesh undergoes a number of changes, including softening, sweetening, decreasing in bitterness, and change in colour.

      During ripening, a chemical in fruit called pectin is converted from a type that doesn’t dissolve in water to one that does dissolve in water. This makes the fruit less firm.

      A lot of the sugar in fruit comes from starches. When the fruit ripens, the long starch hydrocarbon chains break into shorter sugar chains (fructose). This makes the fruit taste sweet. In some fruits, the acids break down, also removing the tart flavour and letting the sweetness take over.

      Green/unripe fruit contains chlorophyll, which is also broken down during ripening. This allows the natural colour (purple, red, orange, yellow) to show through.

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