Tofu, Soy milk and Miso these are products made from soybeans and are colored white but one soybean product stands out from the rest- Soy sauce.
Soy sauce is an east Asian seasoning which originated in ancient China.
To know Why are soy sauce are black while soy milk is white we have to first to explain the color of soybeans.
Soybeans are green when still young but turns yellowish as it turns older, Soy milk among other soy based products are from the older stage of soybeans.

Soy sauce, however is black because it had to undergo a fermentation process, which it means that a chemical change has occurred with effervescence (a bubble of his).
Specifically, the fermented Soybean and wheat floor with the mold Aspergillus oryzae.
However, the entire process of making Soy sauce can take up to 24 weeks from the boiling of Soybeans and Wheat to the fermentation process and finally packaging.
Conclusion
So today we learned that Soy sauce is black because of the fermentation process between soybean and the mold Aspergillus oryzae while Soy milk is white because it comes from mature and yellow soybeans.
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Or read this news about how Nanoparticle is used to treat heart disease which I am not publishing here at publish0x anytime soon:
https://scij.tech.blog/2020/06/01/nanoparticle-absorbs-harmful-plaque-that-causes-atheroscelorosis/
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