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I'm doing an experiment how fast fruits ripen and decay

I'm wondering how to measure the ripeness of a fruit(banana, mango, tomato, kiwi etc.) so that I will get a quantitative results.

I have looked at using penetrometer to see how squishy it is. Is there any other ways to do it?

If not, I'm thinking of getting qualitative results. Is there any tips of making good qualitative results?

thanks


Sorry, I am not sure if this falls into Biology category

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  • $\begingroup$ I suspect the answers will depend greatly on which fruit(s) you are considering measuring. $\endgroup$ – Bryan Krause Mar 1 '17 at 21:53
  • $\begingroup$ At what stage of development will you be observing the fruits? Are they going to be fruits from the supermarket, or do you have access to the trees? $\endgroup$ – Don_S Mar 2 '17 at 13:19
  • $\begingroup$ Just a fruit from the supermarket $\endgroup$ – didgocks Mar 3 '17 at 1:36
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Asides from just eyeballing the change in color/consistency, Wikipedia suggests using iodine for a qualitative measurement (though without reference):

Iodine (I) can be used to determine whether fruit is ripening or rotting by showing whether the starch in the fruit has turned into sugar. For example, a drop of iodine on a slightly rotten part (not the skin) of an apple will stay yellow or orange, since starch is no longer present. If the iodine is applied and takes 2–3 seconds to turn dark blue or black, then the process of ripening has begun but is not yet complete. If the iodine becomes black immediately, then most of the starch is still present at high concentrations in the sample, and hence the fruit hasn't fully started to ripen.

A quantitative method applicable to many kinds of fruit is going to be tricky. If you have a spectrophotometer you could measure the changes in light absorption as the fruit ages. You will probably want to measure the absorptions of control fruits as they age and then compare them to fruits from whatever experiment you perform.

Another possibility is measuring ethylene and/or carbon dioxide production. As fruits ripen they produce more of both these gasses, but this increase does not follow a neat linear correlation with time to put it lightly. Non-climacteric fruits, if you use them, may also be problematic here as they do not show such increase in gas production.

  1. Merzlyak, M. N., Gitelson, A. A., Chivkunova, O. B., & Rakitin, V. Y. (1999). Non‐destructive optical detection of pigment changes during leaf senescence and fruit ripening. Physiologia plantarum, 106(1), 135-141.
  2. Burg, S. P., & Burg, E. A. (1962). Role of ethylene in fruit ripening. Plant Physiology, 37(2), 179.
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