An algae extracted, heat-resistant gelling agent, agar-agar is used in molecular gastronomy to make all sorts of gelified shapes : pearls, spaghetti, lentils, prisms, etc.
Agar-agar is a natural gelling substance stemming from the cell walls of red algae, of the gelidiacees family, like gelidium and gracialaria. It has long been used in several Asian culinary traditions. Moreover, the name agar-agar is of Malay-Indonesian origin and means jelly. A Japanese legend tells that the original manufacturing process of the agar-agar was discovered in the mid-seventeenth century. One winter evening, a Japanese officer would have been offered a traditional dish of jelly concocted from gelidium seaweed boiled in water, by the owner of a small inn. After dinner, the innkeeper would have thrown the remnants of jelly outside. Within a few days and after several cycles of freezing, thawing and drying in the sun, a white substance seems to have appeared which the landlord would have collected and boiled. He would have obtained a gelatin whiter than the original and whose texture in the mouth would have pleased the Japanese ever since. The same process of freezing and thawing is still used today, on a large scale, to extract and purify the agar-agar of the seaweed from which it originates.
Agar-agar is used for its gelling capabilities and the unique properties of the gels obtained by it. Gelling occurs when a solution of agar-agar has cooled in a liquid that was previously brought to a boil. Depending on the species of algae used, gel formation will take place at temperatures between 32°C and 43°C. (90°F and 110°F)
Agar-agar does not impart flavor or smell to mixtures; it actually promotes the release of other aromas in the mouth. It is usually used in very low dosage, since gelling is evident at levels of concentration of agar-agar below 1%. The firmness of the gel is directly proportional to the concentration of agar-agar used in a dish. The weaker the dosage of agar-agar, the more supple and fragile the gel will be; the stronger the dosage, the more firm and brittle the gel will be.
The remarkable heat resistance of agar-agar gels make them excellent stabilizers and thickeners in pie fillings, icings and meringues. This same property is a tremendous asset to the transportation of goods, by allowing greater flexibility in controlling the temperature.
In combination with other vegetable gums, agar-agar may act as a stabilizer in sorbets and ice cream, as well as to improve the texture of dairy products like yogurt and cream cheese. The gelling properties of agar-agar are also used in the preparation of fruit confectionery which are particularly popular in Asia.
About 90% of the production of agar-agar is thus directed towards the food processing industry; the remainder is mainly used in the health field. Agar-agar gel is used as bacterial growth gel in Petri dishes, from microbiology laboratories around the world. In addition, agar-agar is used in dentistry as a material for moulding the teeth. These are just some of the many uses of agar-agar.
Agar-agar is one of the flagship additives of molecular gastronomy. It is used to make dishes with unusual shapes and textures such as pearls and spaghetti gels. There is simply to dissolve the powdered agar-agar in a boiling aqueous liquid, then let it set while cooling, using various techniques. It is also incorporated into preparations using a food siphon to produce very light foams.
Agar-agar preparations are heat resistant, thereby making it possible to serve hot foams and gels.
Agar-agar has the advantage of being calorie-free. It is also 80% fibers and can therefore affect regularity of the bowel.
In jams, agar-agar holds better than pectin and because of a very good release of flavor in the mouth, it amplifies the taste of fruit and thus reduces the amount of sugar needed in a recipe.
Lastly, agar-agar is an ideal vegetable substitute for animal gelatin.
The gelling properties of agar-agar are activated only if the solution is boiled for about two minutes. There is only then to let it rest in a cool place or at room temperature so that it gels.
A hand blender is recommended to dissolve agar-agar. A whisk can also be used but in order to prevent lumps from forming, the agar-agar powder has to be poured slowly and gradually. Another technique is to first dissolve the agar-agar in a small amount of boiling water, which will then be poured into the final preparation. It is important to remember that agar-agar is not soluble in all liquids, but only in water. For example, agar-agar will not dissolve in oil or pure alcohol. Water will therefore have to be added to the mixture.
Animal Gelatin Substitute
Of vegetable origin, agar-agar is an ideal substitute for animal gelatin. As little as 2 g. of agar-agar powder replaces 3 sheets of gelatin, that is to say 6 g. Unlike gelatin, agar-agar is truly tasteless and odorless, which may be preferable for certain recipes. Furthermore, it holds better when removed from a mold and also keeps better. Finally, the agar-agar foam produced with a food siphon also holds better than animal gelatin foam, this property allows for lighter and airier textures.
Agar-agar gels have a firmer texture and are more brittle than gelatin, which, unlike agar-agar gels, usually melts at a temperature approaching that of the inside of the mouth. To reproduce the effect of fondant in the mouth that gelatin has, tara gum can be added to the preparation of agar-agar. This will soften the mixture and make it creamier.
When one tries out a recipe of his/her own, one must be able to determine the right mix of agar-agar and liquid. As the solution of agar-agar gels only during the cooling period, the mixture can be brought to a boil, then only a small amount can be cooled at room temperature. The gelling should usually be done within three minutes or less. If the result seems too runny, there needs only to add a small quantity of agar-agar to the preparation; if it seems too stiff, a small quantity of liquid must be added.
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