The mysterious gelling agent, explained
How do vegetarians and vegans make thick, gelatinous treats? A common problem-solver is agar agar, an algae-derived substance used in place of gelatin and cornstarch. The colorless, flavorless, and odorless substance is sold for culinary use as dehydrated flakes or a powder, and can be sprinkled into everything from jellies and custards to creamy soups to achieve a thick texture.
While agar agar is most similar to gelatin in its technical properties, the two substances are actually quite different. Agar agar sets more firmly than gelatin, and can also withstand very high temperatures without melting. Agar agar is also free from all animal products, as well as gluten, wheat, corn, soy, and yeast. While it’s high in iron, fiber, and calcium, agar agar contains no calories, carbohydrates, or fat.
These unique nutritional properties have actually made for some success when used in obesity and type 2 diabetes studies (where accomplishment was measured via reduced average body weight, fasting glucose levels, and blood pressures, among other factors). Like arrowroot starch and xanthan gum, which also have similar properties to agar agar, the powder and flakes are sold in most health food stores and online. As more people begin to follow special diets, agar agar has been more regularly available for purchase in supermarkets, often in a vegan or gluten-free products section.
While agar agar may be unfamiliar to the average American home cook, it's been used in many other countries for centuries. Anmitsu, a popular Japanese dessert, features cubes of jelly made from agar agar (known as Kanten in Japan), along with fruit, ice cream, and red bean paste. Vietnamese thạch, a gelatinous layered dessert, is made from colored and flavored agar agar. It's also used to make gulaman jelly bars, which are incorporated in many Filipino dishes like halo-halo and buko pandan. Many recipes for Russian ptichye moloko, a chocolate-glazed sponge cake, call for agar agar as opposed to gelatin in the soufflé layer, as it reacts better to being heated.
Curious about cooking with agar agar? Use it instead of gelatin or cornstarch in any recipe (use about half the amount of agar agar than the cornstarch measurement), like coffee jelly, fruit compotes, and DIY Fig Newtons.