Introduction
If you add a tea bag when you drink green tea, the water turns brown. Storms River which is a river in the Eastern Cape province of South Africa has the same phenomenon. Why is the water brown despite its clean natural scenery?
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A local guide who appeared on this TV program explains like this.
Leaves and insects have tannins. When they sink to the bottom of the river and it rains, the tannins that melt in the rainwater seep into the water and the water turns brown.
Thinking from a Plant Perspective
Tannin is commonly found in the bark of trees, leaves, shoots, stems, fruits, seeds, roots, and plants. For example, it is easy to think of the bitter taste of green tea or undercooked persimmons.
This ingredient is soluble in water and has the property of sinking in water. The tannin component also lowers the ph. In other words, when leaves or trees containing tannin fall into the water, the acidity level of the water increases.
What would be the effect of combining the tannin with oxygen (=oxidizing)?
It can be seen that the cross-section of fruits and vegetables turns brown when they come into contact with air. This is actually to protect itself from the plant's point of view. As tannins are oxidized, they harden plant cells. In other words, by making a shield using tannin, the plant itself strengthens its cross-section so that pests cannot easily eat it.
Tannin also prevents infection with bacteria and fungi. Tannin settles enzymes and other protein secretions from bacteria and fungi to prevent infection with plants.
Plants are geniuses!
