Agar-agar, known as just agar in culinary circles, is a plant-based gelatin derived from seaweed. The white and semitranslucent vegetable gelatin is sold in flake, powder, bar, and strand form, and can be used in several dairy-free and vegan recipes as a stabilizing and thickening agent. It is often promoted as a vegetarian substitute for regular gelatin, which is made from animal products. Agar-agar is also used in gluten-free recipes as a thickener and is very nutritious.
- Also Known As: Kanten
- Sold As: Powder, flakes, bars, and strands
- Use: Vegetarian substitute for gelatin
What Is Agar-Agar?
This jellylike substance is a mix of carbohydrates that have been extracted from red algae, a type of seaweed. Agar has several uses in addition to cooking, including as a filler in sizing paper and fabric, a clarifying agent in brewing, and certain scientific purposes. It is also known as China glass, China grass, China isinglass, Japanese kanten, Japanese gelatin, and dai choy goh, and is used in certain Japanese dessert recipes.
Agar-Agar vs. Gelatin
The main difference between agar and gelatin is from where they are derived. Whereas animal-based gelatins are made from livestock collagen (from the cartilage, bones, skin, and tendons), agar-agar is purely vegetarian, coming from the red algae plant. The two setting agents also behave differently and need to be prepared in distinct ways when incorporating into a recipe. Agar-agar needs to boil in order to set, while gelatin can simply dissolve in warm water; that is because agar melts at 185 F, whereas gelatin melts at 95 F. Agar also sets more quickly than gelatin and doesn't need any refrigeration.
The resulting recipe will also have subtle variances: Dishes made with agar will be firmer and less creamy and jiggly than those made with gelatin. Agar-agar recipes also stay firm when exposed to higher temperatures, while gelatin loses some of its stability.
Agar-agar is sold as flakes, powder, bars, and strands. The seaweed is typically boiled into a gel, pressed, dried, and then crushed to form agar flakes, blended into a powder, freeze-dried into bars, or made into strands. The powder is less expensive than flakes and the easiest to work with as it dissolves almost immediately, whereas the flakes take a few minutes and need to be blended until smooth. The powder is also used in a 1:1 ratio when substituting for gelatin—when using flakes, 1/3 the amount of gelatin called for should be added. The agar bars, sticks, and flakes can be processed into powder form in a blender or food processor. Similar to gelatin, flavored and colored versions of agar are available.
In cooking, agar-agar is used as a vegetarian alternative to gelatin in a variety of dishes, including puddings, mousses, and jellies, as well as ice cream, gummy candies, and cheesecake. It is an important ingredient in the Japanese dessert anmitsu, which calls for kanten jelly, a mixture of agar-agar, water, and sugar.
How to Cook With Agar-Agar
Before agar can be added to a recipe, it needs to be dissolved in water and then boiled; it cannot be simply dissolved in a liquid or added directly to food. Dissolve the agar in a liquid in a small saucepan over medium-high heat, bring to a boil, and then simmer until slightly thickened, about five to seven minutes. Agar powder dissolves more quickly than flakes and strands, which need extra soaking time and stirring to fully dissolve. (Flakes, bars, and strands can be processed into powder before using.)
To use agar flakes in a recipe, measure 1 tablespoon for every cup of liquid; for agar powder, use 1 teaspoon to thicken 1 cup of liquid. (The general rule of thumb when substituting agar for gelatin is to use an equal amount of agar powder and one-third the amount of flakes as gelatin.) Once the dissolved agar is added to a recipe, it will take approximately an hour to set at room temperature. Most recipes using agar are eaten cold so the dish will need to be refrigerated.
It is important to note that foods high in acidity, such as citrus fruits, strawberries, and kiwi, may require additional amounts of agar to fully gel.
What Does It Taste Like?
Agar-agar is completely odorless and tasteless, making it an ideal gelling agent for adding to any type of recipe.
Of course, gelatin can be substituted for agar, but if a vegetarian alternative is needed, there are a few other options to consider. One is another type of seaweed called carrageen, which is used to produce carrageenan, a thickening agent extract. It sets more softly than gelatin, and it's best to use the whole dried form versus the powder. The dried seaweed should be rinsed well and soaked for 12 hours in water and then boiled and strained out. One ounce of carrageenan should be used per 1 cup of liquid.
Pectin powder, derived from citrus fruit and berries, is often used to thicken jams and jellies and can be used in place of agar. It does include sugar, so it is best in sweet recipes. A manufactured product available from a variety of brands is an unflavored vegan gel, a vegetarian gelling powder that is a combination of a variety of ingredients including carrageenan.
Where to Buy Agar-Agar
Agar-agar can be found in the natural food section of the supermarket, health food stores, Asian groceries, and online. Agar flakes are more expensive than the powder (and gelatin), but less is needed in recipes. Agar strands are the least expensive option.
All forms of agar-agar should be stored in an airtight container in a cool, dry spot such as the pantry, where it will last at least eight months.
Nutrition and Benefits
Agar-agar contains few calories and is low in saturated fat and cholesterol. It is an excellent source of calcium, iron, folate, fiber, and manganese. There is no sugar or carbohydrates in agar, making it an aid to weight loss. In fact, it's the main food in the kanten diet, which is a popular weight loss plan in Japan.
Because of the high concentration of fiber (80 percent), agar is often used as a laxative. In Eastern traditional medicine, agar has been used to treat conditions like diabetes and constipation. Agar is also beneficial in preventing bone loss due to the high concentrations of calcium and manganese.
Morselli B, Neuenschwander B, Perrelet R, Lippuner K. Osteoporose-Diät [Osteoporosis diet]. Ther Umsch. 2000;57(3):152-160. doi:10.1024/0040-5918.104.22.168