Difference between revisions of "Agar"
(Created page with "{{Stub}} '''Agar''' or '''agar-agar''', is a jelly-like substance, obtained from red algae. ==Composition== Agar consists of a mixture of two polysaccharides: agarose and aga...") |
|||
| (2 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
{{Stub}} | {{Stub}} | ||
| + | [[File:Agar powder OTC.jpg|thumb|350px|Food-grade powdered agar from the store.]] | ||
'''Agar''' or '''agar-agar''', is a jelly-like substance, obtained from red algae. | '''Agar''' or '''agar-agar''', is a jelly-like substance, obtained from red algae. | ||
| Line 24: | Line 25: | ||
==Handling== | ==Handling== | ||
===Safety=== | ===Safety=== | ||
| − | Agar is non-toxic and is used as food. You should not, however, consume lab-grade agar | + | Agar is non-toxic and is used as food. You should not, however, consume lab-grade agar. |
===Storage=== | ===Storage=== | ||
| Line 52: | Line 53: | ||
[[Category:Materials available as food grade]] | [[Category:Materials available as food grade]] | ||
[[Category:Edible chemicals]] | [[Category:Edible chemicals]] | ||
| + | [[Category:Natural gums]] | ||
Latest revision as of 21:07, 8 December 2019
 |
This article is a stub. Please help Sciencemadness Wiki by expanding it, adding pictures, and improving existing text.
|
Agar or agar-agar, is a jelly-like substance, obtained from red algae.
Contents
Composition
Agar consists of a mixture of two polysaccharides: agarose and agaropectin, with agarose making up about 70% of the mixture. Agarose is a linear polymer, made up of repeating units of agarobiose, a disaccharide made up of D-galactose and 3,6-anhydro-L-galactopyranose. Agaropectin is a heterogeneous mixture of smaller molecules that occur in lesser amounts, and is made up of alternating units of D-galactose and L-galactose heavily modified with acidic side-groups, such as sulfate and pyruvate.
Gelidium agar is used primarily for bacteriological plates. Gracilaria agar is used mainly in food applications.
Properties
Agar is a yellowish, beige or brown (depending on the source) gel, which dissolves slightly in water. It exhibits hysteresis, melting at 85 °C and solidifying from 32–40 °C. This property lends a suitable balance between easy melting and good gel stability at relatively high temperatures. Since many scientific applications require incubation at temperatures close to human body temperature (37 °C), agar is more appropriate than other solidifying agents that melt at this temperature, such as gelatin.
Availability
Agar can be bought from many food stores, as well as online.
Projects/Uses
- Food (deserts)
- Vegetarian substitute for gelatin
- Clarifying agent in brewing
- Make agar plates
- Grow microbial cultures
- Measure microorganism motility and mobility
- Make salt bridges and gel plugs
Handling
Safety
Agar is non-toxic and is used as food. You should not, however, consume lab-grade agar.
Storage
Agar should be kept in dry and clean places, to avoid rotting. A plastic bottle or bag is usually sufficient. Agar is best stored between +15°C to +25°C.
Disposal
No special disposal is required. Discard it as you wish.
