• Question: why are ripened fruit's and vegetables a different colour to when they are growing?

    Asked by to Kate, Kieren, Nicola, Rowena, Roy on 17 Mar 2014. This question was also asked by .
    • Photo: Rowena Fletcher-Wood

      Rowena Fletcher-Wood answered on 17 Mar 2014:

      Fruits and vegetables ripen by a chemical reaction with ethylene. This is usually produced by the plant and fed to the fruits, but in bananas it is actually produced by bananas, which is why if you put a banana next to other fruit they ripen, and why bananas always ripen fast and turn brown.

      As a fruit ripens, starch is broken down and turned into sugar, which is why they taste sweeter. Green chlorpyhll and starchy cell walls are broken down a bit to make a softer fruit and scent is given off to attract wildlife to eat them. The colour changes we see are the chlorphyll being broken down and cells mashed up.

    • Photo: Kate Nicholson

      Kate Nicholson answered on 18 Mar 2014:

      They usually contain both pigments but before they are ripe the green chlorophyll dominates the colour we see. As they ripen this is broken down and disoolves, leaving the other coloured pigments to dominate the colour.

      Tomatoes are a good example, they contain two pigments for photosynthesis—chlorophyll, which is green, and lycopene, which is red. When tomatoes start to grow, they contain much less lycopene than chlorophyll, which gives them their green color. But when harvest season arrives, the days shorten and temperatures drop, causing chlorophyll to dissolve and lycopene to take over the shade of the fruit. During this time, sugar levels rise, acid levels drop, and the tomato softens. It becomes ready to eat.

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