Knowde Enhanced TDS
Identification & Functionality
- Ingredient Name
- Food Ingredients Functions
- Ingredients
- Agar
- Food Additive Number
- E 406, INS 406
- Technologies
- Product Families
- Sources
Agar, or Agar-Agar, is a dried hydrophilic, colloidal polygalactoside
extracted from Gelidium Cartilagineum, Gracilaria Confervoides and
related red algae. These seaweeds grow in the ocean on the rocks,
from tide line out to depths of 120 feet, in many parts of the world. The
weeds are harvested by waders along the shore at low tide, raked by
fishermen from small boats, and picked by skin divers or divers in suits.
This old “natural method” of extracting the Agar from the seaweed
has been replaced by commercial methods that are still based on the
fundamental principles of hot-water extractions, cooling to form a
gel, freezing, thawing, and drying. The latest mechanical, scientific
processing utilizes chemical treatment of the weed, pressure extraction,
artificial freezing and drying, chemical bleaching, and many more
advanced methods.
Features & Benefits
- Food Ingredients Features
- Product Properties
Physical
Agar is sold in bundles of thin translucent strips of 0.2–1 cm in width
and 30–40 cm in length. It is also available in cut, flaked, granulated,
or powdered forms. Powdered Agar is white to pale yellow and is
practically odorless and tasteless. Food, bacteriological, medicinal,
and dental grades are available.
Solubility
Agar is insoluble in cold water, slowly soluble in hot water, and soluble
in boiling water. It is insoluble in most organic solvents. Agar’s maximum
swelling rate is at pH 8.9. It tends to swell less in acid media than in
alkaline media.
Viscosity
The viscosity of Agar sols is influenced by the raw material used and
the processing conditions employed. Viscosity is also affected by heat,
pH, and the presence of electrolytes but is relatively constant from
pH 4.5–9. Once gelation begins, however, viscosity at constant
temperature increases with time.- Chemical Characteristics
The structure of Agar is not completely known. It is considered to
be a non-sulfated linear molecule composed of alternating residues
of 1.3-b-galactopyranose and 1.4–3.6 anhydro-a-L-galactopyranose
together with a non-gelling or very weak gelling agaropectin composed
of a complicated acidic polymer containing ester sulfate groups and
organic acid groups. It occurs naturally as a calcium salt, although
commercial Agars have also introduced sodium, magnesium, and
potassium ions. A good-quality Agar contains not more than: 20%
moisture, 6.5% ash, 0.5% acid-insoluble ash and 1% insoluble matter.
Applications & Uses
- Markets
- Applications
- Food & Nutrition Applications
- Uses
Agar is used primarily for its gelling properties, the wide difference between gelation temperature and gel-melting temperature, and the heat resistance of its gels. It is also used for its emulsifying and stabilizing properties. It is practically indigestible.
- Desserts
- Gels
- Laxatives
- Pharmaceuticals
- Microbiology
Food Industry
Agar is used as a stabilizer in cookies, cream shells, piping gels,
pie fillings, chiffon pies, icings, and meringues as an anti-tackiness
ingredient. Agar, at a sue level of 0.2–0.5% in icings, prevents the
sugar from adhering to the wrapper. The drying time of the icing can
be regulated by varying the amount of Agar used. The use of 0.5–1.0%
Agar, based on sugar, increases the viscosity of doughnut-glaze
stabilizers, increases its adherence to the doughnut, and provides
quicker setting and flexibility with reduced chipping and cracking.
Agar has been used with success as an anti-staling agent in breads
and cakes. Agar is useful in low-calorie, non-starch breads, biscuits,
and desserts as a non-nutritive bulking agent.
Agar is used at 0.5–2.0% of the broth weight as a thickening and
gelling agent by poultry, fish, and meat canners to eliminate transit
damage to fragile tissues. Agar, added to Guar Gum, gives better
stabilization of water and fat in pet foods as well as meat pies.
Canned baby foods, jams and marmalades also use Agar.Pharmaceutical Industry
Agar has been used as a laxative, since it forms a smooth, nonirritating
bulk. In addition, it is not habit forming. It is also used as a suspending
agent for barium sulfate in radiology, slow-release capsules, suppositories,
surgical lubricants, and emulsions, and can be used as a carrier
of topical medicaments. In prosthetic dentistry, Agar is used to make
accurate negative casts of teeth, sockets, and entire edentulous gums
in order to form accurate artifacts.
Microbiological Uses
Agar—low in metabolizable or inhibitory substances, debris, and
thermoduric spores—with a gelation temperature of 35–40° Celsius,
which is readily soluble and has good gel firmness, clarity, and
solubility, is ideal for the propagation and pure culture study of yeast,
molds and bacteria. No completely satisfactory substitutes are known,
and Agar is commonly used at 1–2% for this purpose. At 0.007–0.08%,
Agar prevents the entry of oxygen into liquid media, making cultivation
of anaerobes feasible in air-exposed broths.
Powdered Agar is available in a range of mesh sizes and gel strengths.
Powdered Agar can also be custom ground and blended to meet
customer specifications.- Qualities
- Uniform Gelling
- Suspending Agent
- Stabilizing
Technical Details & Test Data
- Gel Formation
The ability of Agar to form strong gels with a sharp transition
temperature is one of its most important properties. Agar is unique
among gelling polysaccharides in that gelation occurs at a temperature
relatively far below the gel-melting temperature. A 1.5% Agar sol
prepared by boiling will not congeal until the temperature drops to
32–39° Celsius to form a firm, resilient gel that does not liquefy below
85° Celsius. Many uses of Agar depend on this high hysteresis.
Agar forms gels at concentrations as low as 0.04%. These threshold
gels are valuable for their protective-action, diffusion-prevention, and
texture-enhancement properties. The usual concentration range for gel
forming is usually 1–2%. These gels are useful for their transparency,
thermal reversibility, relative permanency, and low syneresis. Solutions
viscosity, gelling temperature, gel strength, degree of syneresis, and gel
clarity may vary with the Agar seaweed source. The Agar gel structure
may be strengthened by the addition of large amounts of sugar or
dextrin. The elastic deformability and breaking strength are greatly
increased by using Locust Bean Gum. The gel strength of Agar
decreases with its age. Generally, Agar gels shrink and exude some
liquid from their surface (syneresis) with increasing concentration- Compatibility
Agar is compatible with most plant hydrocolloids, such as Locust
Bean Gum, as well as other carbohydrates and proteins. Electrolytes
reduce the swelling power of Agar, as do alcohol and other organic
solvents miscible with water. The action is twofold: to reduce the net
electric charge and to dehydrate the gel. The electrolyte at 0.1N
concentration and the Agar colloid compete for the water that is
present. This action is reversible.- Preservatives
Agar, like most hydrocolloids, is subject to bacterial attack: in fact,
viable spores of thermoduric bacteria are present in Agar. Methyl and
parahydroxybenzoate, at a maximum of about 0.17% and 0.03%
respectively, are, together, effective as a preservative.