If you’re American, chances are that your introduction to agar was in high school biology class, where it’s often used as a growing culture in petri dishes. Agar is also a popular thickener and gelatin substitute used in dessert dishes.
Agar is a versatile, neutral-tasting seaweed. A kinder, less processed thickening agent than gelatin, which is made from cows’ hooves, agar is commonly used in Asian desserts. The name comes from the Malay word “agar,” which means “jelly.” In Japan, agar is known as “kanten.”
Dissolve agar in hot or boiling liquid for at least 1 to 2 minutes to unleash its powerful gelling properties. It’s best to let agar flakes sit in the liquid, usually fruit juice or soy milk, at room temperature for about 10 minutes before bringing the liquid to a boil to ensure everything is thoroughly mixed.
You can substitute powdered agar for equal amounts of gelatin.If you’re using agar flakes, you’ll need to up the quantity 3:1, for example, 3 teaspoons [1 tbsp.] agar flakes = 1 tsp agar powder.Generally speaking, for a “jello-like” texture, you’ll need about 2 teaspoons of powder or 2 tbsp. of flakes added to about 2 cups of liquid. Use less for mousses, more for “jigglers.”
With highly acidic fruits like strawberries, you’ll need to add more agar.Certain fresh fruits, including pineapple, kiwi, mango and peaches, actually disable agar’s gelling properties. You can still use these fruits–you just need to cook them first.
Buying agar powder or flakes in a health food store is expensive–usually about $6 for about 6 tablespoons. To save money, buy large packets of whole agar in an Asian grocery, and then gently pulse it into flakes in the food processor. The result? A few years’ supply for only about $1.40.
The most common mistakes when making a dessert with agar is not adding enough agar, or not ensuring it’s properly dissolved before molding.