Agar-agar is a hydrocolloid extracted from red seaweeds that is widely used in the food industry.
In its gelling power, agar is outstanding among the hydrocolloids. Among its major properties one can mention its high gel strength at low concentrations, low viscosity in solution, high transparency in solution, thermo-reversible gel and sharp melting/setting temperatures. Agar-agar is also used on a lesser scale in other industrial applications.
RAW MATERIAL
Agar-agar is extracted from several types and species of red seaweeds belonging to the Rhodophyceae class. These agar-containing seaweeds are called agarophytes and the major commercial species are Gracilaria, Gelidium and Pterocladia. The agar content of seaweeds varies according to the conditions of seawater. Carbon dioxide concentration, oxygen tension, water temperature and intensity of solar radiation can have significant influence.
Seaweeds are usually harvested manually by fishermen in low depths at low tides or by diving using appropriate equipment. After being harvested, seaweeds are placed under the sun to dry until they reach a humidity level that is ideal for processing.
FUNCTIONALITY AND APPLICATIONS
FOOD INDUSTRY
An agar-agar solution in hot water forms a characteristic gel after setting, with a melting point between 85º to 95º C, and a gelling point between 32º a 45º C. This physical property makes the gel very useful as an additive when used in many applications in the food industry.
Milk Products
Ice Creams, Puddings, Flans, Yogurts, Fermented Milk, Sorbets, Gelled Milk
Sweets and Confectionary
Gum drops, Candy bars, Jelly candies, Jams, Marmalades, Comfitures, Dessert Gel, Meringues
Meat Products
Pureed Meats, Canned fish, Poultry
Beverages
Clarifying and refining of juices, beers, wines and vinegars
Bakery
Cake icings, Pie fillings, Bread dough, Chiffon pies
OTHER INDUSTRIAL APPLICATIONS
Agar-agar gel has the interesting property of inhibiting the characteristic liquefying that occurs in the enzyme action of microorganisms. This property finds a wide variety of applications in the medical and pharmaceutical industries. Agar-agar is used as a substratum in preparing bacteria cultures in microbiology, as laxatives and therapeutic agents in the treatment of malfunctions of the digestive tract, as a retarding agent and carrier in the management of medicines, antibiotics, vitamins, as a barium sulfate suspension agent in radiology, as a stabilizer in cholesterol solutions, and as a suspension agent in several types of emulsions. Agar-agar has other industrial applications as well where a gelling agent is needed, such as in dental prosthetics, photographic emulsions, differentiation of proteins through electrophoresis, chromatography through exclusion of sizes, molding of materials and as plant culture tissues in biotechnology.
