seaweeds in a sodium form, so in the presence of salt (which is made up of Na+ and Cl- ions), the
alginate will tend to stay in its sodium form and will not form a jellified outer layer.
Calcium can impart a slight taste to the beads, so they should be left in the calcium solution for as
short as possible (as soon as the outer layer is sufficiently strong to handle the bead it should be
removed from the solution) and the beads should always be rinsed in pure water before they are
The ability of an alginate solution to form these beads in contact with calcium is due to their ability to
form a gel instantaneously on contact with calcium. This also makes it very difficult to form a solid gel,
as with agar agar and gelatine, because the gel will set immediately, and before it has time to be
decanted into the appropriate container. This can be resolved by adding to the mixture a calcium
sequestrant – this will hold the calcium out of solution for a while, allowing the gel to be placed in the
appropriate container, and will gradually start to release calcium allowing an even gel to form.
Also, the addition of tap water, or any milk based product, should be avoided since it may contain
significant amounts of calcium which may trigger early and uneven gel formation, which may produce
lumps in the mixture. Therefore, it is best to use pure juices extracted directly from vegetables, to
ensure there is no sodium or calcium contamination which may prevent the beads from forming.
As explained, the major limitations of these alginate beads is that they cannot be formed in the
presence of salt. If a salty bead is required, the alginate may be replaced by low methylated pectin –
low methylated pectin is also a gelling agent that forms a gel in the presence of calcium. The formation
of a gel is not inhibited by the presence of sodium, so beads containing pectin can be made from salty
preparations. However, pectin is a very effective thickener (its primary use is for making remouldable
glazes for decorating tarts, where the presence of some acid is needed), so the liquid used to make