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How do edible water bottles work? © Getty Images

How do edible water bottles work?

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Yummy! Edible membranes are being used to contain water.

Edible liquid bubbles were originally developed for molecular gastronomy chef Ferran Adrià. Now, start-up company Skipping Rocks Lab has turned this into Ooho! – a bite-sized blob of water. The water is contained in an edible membrane that is made from two tasteless ingredients: sodium alginate (usually derived from seaweed) and calcium chloride. Both are already used in the food industry and are completely safe. Currently, the membrane only lasts a few days before breaking down but the developers are working on tougher versions that could be licensed to drinks companies.

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1

Shape

Water is frozen into a ball so that it holds its shape, and to keep the water molecules from mixing with the membrane chemicals.

2

Dip

The ice ball is dipped into calcium chloride solution. The outer layer of ice melts and some of the calcium ions diffuse in.

3

Alginate

A second bath in warm sodium alginate solution forms the membrane. Calcium ions replace sodium atoms in the alginate and bind the molecules together.

4

Polymer

Unlike sodium, calcium has two positive charges. This lets it bond to two alginate chains at once, tangling them up.

5

Thaw

After two to five minutes, enough of the alginate molecules have polymerised together to form a stable skin and the ice melts into a liquid centre.

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