Breaking Boba -the chemistry of bubble tea (Pt. 2)

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The last article (Pt. 1) covered black pearls and popping boba. Black pearls use hydrogen bonding between flour polymer to form a gel pearl, and popping boba uses ionic bonding to form the skin.
Screen Shot 2018-12-25 at 9.38.49 PMPt. 2 focuses on two other kinds of boba: grass jelly and lychee coconut jelly.


Guess what, the grass jelly is actually made of grass! To be specific, it is made from this type of grass: Platostoma palustre. The fresh plant was sun-dried first, then boiled in baking powder water solution for two hours. The baking powder makes the solution basic, and it breaks down the leaves to releases the pectin within, a natural polymer.

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Pectin is found in many fruits and it is the polymer responsible for jam gelation. In the hot water, pectin moves freely, and the solution is liquid. As the solution is cooled down, the pectin is entangled to each other and can no longer move. The grass jelly is formed when the solution is cooled down.


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Lychee coconut jelly, sometimes called Nata, is not the meat of a coconut. Like tofu is from soy milk fermentation, lychee coconut jelly is made from bacterial fermentation of coconut water.  Lychee is added to the name because coconut jelly usually has artificial lychee flavor.

Microbial cellulose, a fancy way to say bacterial goo, is a polymer that some types of bacteria secret. They are responsible for the gross slimy and slippery bacterial mold, and also yummy lychee coconut jelly.  Komagataeibacter xylinus is a strain of bacterial mostly known for cellulose production, and when added to coconut water, it product jelly.

e636f015d67119b0c663380da11946b5.jpgBiker jacket made microbial cellulose from source: pinterest.com

Microbial cellulose is not only useful in food kingdom. Because these celluloses are safe for the body, they have been used for wound dressing, tissue engineering and even cloth! So don’t be grossed out by these bacterial goos, they are actually quite useful!


That is all the stories I can tell you about boba! Let me know what is your favorite type of boba!

 

 

 

 

Published by

Huang Zhuojun

I'm a Ph.D. student, studying Materials Science and Engineering at Stanford University.

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