A salt is a compound derived from the joining of one positive
ion (other than hydrogen H+) with one negative ion (other than
hydroxide OH- ion). Ions can be metals (sodium, potassium), nonmetals
(carbon), acids (lactic acid) or bases, each providing either
a positive or negative ion. Salts are usually very soluble in water.

Table salt, or sodium chloride, is well known for its flavor enhancing
and preservative qualities, but in molecular gastronomy, calcium
salts are used for gelling with sodium alginate.

Three calcium salts, derivatives of three acids (lactic, gluconic,
chloric), are usually used in molecular gastronomy. However,
calcium lactate is more popular, since it leaves no aftertaste,
whereas calcium chloride leaves a certain bitterness in the mouth,
even after rinsing the spheres with water.

The acid part of calcium lactate is derived from lactic acid, an acid
available during the fermentation of sugars by lactobacilli bacteria.
These same bacteria are needed to make yogurt, cheese and wine.
For people with calcium deficiency, calcium lactate is one of the
most recommended supplements due to its high absorption rates.

Calcium lactate is found in milk powder, but it is also used as a
substrate for yeast in bakery products, an acidity stabilizer in
baking powder, and a firming agent for grapefruit and canned peas.