Today, we had learnt about the iodine staining or iodine test that being used to test the presence of starch.
As the fruit becomes ripen, the burst ethylene production will activate the enzymes such as kinases, amylases, and hydrolases
Basically, the starch is present or have slightly higher content while unripen
when the fruit is ripen, the ethylene initiates the metabolic pathway of the conversion of the starch to sugar (glucose or sucrose)
During iodine test, the fruits that have been stained and turned blue/dark blue color shows the presence of starch
(Iodine is very sensitive to the presence of starch)
However, the results are not pretty convincing
the iodine solution should be at the right concentration
besides that, different varieties of the fruits may affect the result
This is due to varied genotypes present in each varieties
That's all
Have a nice day ^^
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| Fruit samples for iodine test |
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| left: unripen papaya; right: semi-ripen |
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| left: ripen banana; right: unripen banana |
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| left: sweet potato; right: radish |
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| Cross section of radish that has been stained with iodine solution |
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| Unripen papaya shows no changes to the surface after being stained. |
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| Sweet potato contains a lot of starch; positive result |
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| No changes |
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| The unripen banana has intense color of blue stain |
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| Comparison between ripen and unripen banana |
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| Mango-unripen- |
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| Staining procedure (stain for 1 min) |
Note: Sweet potato is known as storage organ
it contains rich starch content
the sugar (glucose or sucrose; simplest sugar) is used for immediate-use
