Agar-AgarBotanical Name: Gelidium amansii (KUTZ)
Family: N.O. Algae
Synonyms: Japanese Isinglass.
Part Used: The mucilage dried, after boiling the seaweed.
Habitat: Japan, best variety; Ceylon and Macassar.
Description-: A seaweed gathered on the East Indian coast and sent to China, it is derived from the various species of Sphaerococcus Euchema and Gelidium. It is brownish-white in colour with thorny projections on its branches; the best variety, known as Japanese Isinglass, contains large quantities of mucilage. The seaweed after collection is spread out on the shore until bleached, and then dried; it is afterwards boiled in water and the mucilaginous solution strained, the filtrate being allowed to harden, and then it is dried in the sun. The time for collection of the Algae is summer and autumn when the bleaching and drying can take place, but the final preparation of Agar-Agar is carried out in winter from November to February. The Japanese variety is derived from several kinds of Algae and comes into European commerce in two forms: (1) In transparent pieces 2 feet long, the thickness of a straw, prepared in Singapore by treating it in hot water. (2) In yellowish white masses about 1 inch wide and 1 foot long. The latter is the form considered the more suitable for the culture of bacteria.
Constituents: Agar-Agar contains glose, which is a powerful gelatinizing agent. It is precipitated from solution by alcohol. Glose is a carbohydrate. Acetic, hydrochloric and oxalic acids prevent gelatinization of Agar-Agar.
Medicinal Action and Uses: Agar-Agar is widely used as a treatment for constipation, but is usually employed with Cascara when atony of the intestinal muscles is present. It does not increase peristaltic action. Its therapeutic value depends on the ability of the dry Agar to absorb and retain moisture. Its action is mechanical and analogous to that of the cellulose of vegetable foods, aiding the regularity of the bowel movements. It is sometimes used as an adulterant of jams and jellies.
Dosage and Preparations: It is usually administered in small shreds mixed with fruit, milk or any convenient vehicle. It is not wise to give it in powder, as this gives rise to irritation in some cases. 1/2 to 1 ounce may be taken at a time. 1 ounce to a pint of boiling water makes a suitable jelly for invalids and may be flavoured with lemon.
Other Species: Ceylon Agar-Agar, or Agal Agal, which is the native name of Gracillaria lichenoides, is largely used in the East for making soups and jellies. Gigartina speciosa, a variety found on the Swan River, was erroneously supposed to have formed the edible swallow's nest, but it has been ascertained that this delicacy comes from a peculiar secretion in the birds themselves. Macassar Agar-Agar comes from the straits between Borneo and Celebes and consists of impure Euchema Spinolum incrusted with salt.