What is Agar?
Agar-agar, usually seen abbreviated as agar, is a gelatinous substance derived from red algae. There are a number of uses for agar, although most people are familiar with it as the culture medium in petri dishes. Agar is also perfectly edible, and in addition to appearing in regional cuisine, it is also used as a thickening agent in candies and other foods. Since agar is derived from plant material, it has the advantage of being vegetarian, unlike gelatin derived from animal sources.
In microbiology, agar is an important part of the equipment in a laboratory. Because agar is not protein-based, it is not as readily digested by bacteria. When scientists are trying to grow a culture, agar is the growth medium of choice, since it will not turn into a cloudy bacterial soup like animal derived gelatins can. The agar can be enriched with nutrients for the bacteria to feed on, but the agar itself will remain stable.
In cooking, agar is extremely useful. In parts of Asia, agar is used as an ingredient in soups and jellies. Outside of Asia, agar appears in a wide range of foods, along with two other plant based gelatins, carrageen and alginate. In foods which need to be gelled, agar is often employed. It does behave slightly differently than protein based gelatins, and tends to be slightly more slimy, sometimes creating a strange texture. For vegetarians, agar makes foods like marshmallows, jelly beans, and gummy bears possible.
The primary source for agar is Gracilaria lichenoides, harvested on the Western coast of the United States and in parts of Asia. To extract the substance, the algae is boiled, cooled, purified, and dried. Pure agar comes in a number of forms including blocks, flakes, and granules. It is usually translucent, unless it has been dyed before drying. To convert agar into a usable form, it is rehydrated with water. It should be kept in a cool dry place before use.
Many grocery stores sell agar which is suitable for human consumption, often in the same area which holds vegetarian alternatives. Laboratory grade agar is sold through scientific supply companies. Although food grade agar can sometimes be used in a lab, agar intended for scientific use should not be consumed, in case substances which may be harmful have been added to it. Since labeling laws for laboratory supplies are not as stringent as those for foods, you cannot be certain that a package of agar is safe to eat if it has been labeled for lab use.
Written by S.E. Smith
