Alginic acid is a thick, jellylike substance extracted from seaweed and used an acid stabilizer and thickener in a wide variety of commercially processed foods such as ice creams, puddings, flavored milk drinks. Even though it is typically used commercially it has become popular in restaurants using "molecular gastronomy" to prepare everything from cocktails to beet beads.
Texturas, from Spain sells algin on line. We've posted Textura's recipe for Melon Caviar below which uses algin and calcic (calcium chloride) as the main ingredients.
This recipe produces little spheres of melon that can be used in whatever way you'd like using molecular gastronomy techniques. Recipe by Texturas, Spain.
250g cantaloupe juice
2g algin (sodium alginate)
2.5g calcic (calcium chloride)
Mix the Algin with 1/3 of the melon juice and blend. Mix in the remaining 2/3, strain and set aside.
Dissolve the Calcic in the water. Fill 4 syringes with the melon and Algin mixture.
Expel it drop by drop into the Calcic base. Remove after 1 minute, strain and rinse the resulting caviar in cold water.