Hi I am doing a research project on banana ripeness and cannot find a way to tell the ripeness of a banana from the inside of it. I cannot use taste to measure the ripeness but I would really like to have a chart of some kind and if possible a url where you found the chart. Thank you!

  • Can you explain what you're actually trying to accomplish? Why would a chart be necessary?
    – Cascabel
    Commented Aug 29, 2013 at 1:03

2 Answers 2


Ripe bananas are softer and sweeter. You can pretty easily tell how ripe a banana is simply by biting or cutting into it, or even poking it with a finger. Ripe bananas are also more prone to bruising, which is visible on the inside of the banana as well.

If you really want to try to measure, you could indeed try to measure the sugar content. As bananas ripen, they get sweeter because starch is converted into sugar, so the sugar content should indicate ripeness. You'd need a refractometer to do that, not generally an everyday household item.

  • Wouldn't you need to know the ratio of sugar to starch rather than absolute sugar content?
    – Carmi
    Commented Aug 29, 2013 at 18:08
  • @Carmi I don't think so. The sweetness you're tasting as it ripens is just the sugar, not the lack of starch. And in any case, yellow bananas are all the same variety; the starch content is not really going to be particularly variable. I don't know exactly how constant it is, but it's definitely close enough for a first approximation, especially for a research project like this.
    – Cascabel
    Commented Aug 29, 2013 at 18:38
  • The sweetness is certainly just the sugar. However, with regards to ripeness, it seems to me best defined as how much of the starch was converted. Wouldn't the starch content vary by soil, latitude and season?
    – Carmi
    Commented Aug 30, 2013 at 10:26
  • @Carmi I know that the ratio of sugar to sugar plus starch (lower error than sugar to starch) might be a better measurement. But just measuring the sugar is probably good enough, and way better than anything else you can do that easily. Bananas really aren't very variable.
    – Cascabel
    Commented Aug 30, 2013 at 14:19

I think that the best, most accurate, measure of the ripeness of a banana is the ratio of sugar to starch.

The absolute sugar levels (ratio to mass) may be misleading, as only starch is converted to sugar, and the amount of starch is variable.

If you don't need very high accuracy, you may be able to use colour as a proxy for sugar content. The banana flesh will turn darker as it becomes sweeter. I know that hospitals use a device for checking if newborns are jaundiced. It basically measure the "yellowness" of the skin. Something like that would work well here. At the very least, a digital camera and computer will give you a decent sense of relative yellowness.

  • A digital camera and computer and very very controlled lighting will get you started, maybe, but the difference in color is fairly small and digital cameras aren't that precise.
    – Cascabel
    Commented Aug 29, 2013 at 18:39
  • @Jefromi Agreed, the difference is fairly small until the banana goes a little over-ripe. I did recommend professional equipment too, but it's probably a bit much for this project, which sounds suspiciously like homework.
    – Carmi
    Commented Aug 30, 2013 at 10:28

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