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How Calcium Turns Seaweed Extract into Gel
Brown seaweed contains alginate, which is made of long chain molecules that slide past each other in water, so the liquid stays runny. When you add calcium ions, they wedge between pairs of chains like clamps and build a network that traps the water, making a firm gel.
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In the picture
- The runny liquid: without calcium, the seaweed extract solution pours out freely.
- A long alginate chain molecule: on its own, it slides past the other chains.
- A calcium ion wedged between two chains, clamping them together like an egg in an egg box.
- The gel: the clamped chains form a network that holds the water in, so it does not pour.
Examples
- Popping boba in bubble tea: drops of juice mixed with alginate turn firm when they fall into a calcium bath.
- The soft paste a dentist uses to make a mould of your teeth sets because of alginate.
Key takeaways
- Alginate is a long chain molecule taken from brown seaweed.
- Calcium ions link the chains in pairs, turning a liquid into a gel that traps water.
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