Seasoned Advice is a question and answer site for professional and amateur chefs. It only takes a minute to sign up.
Sign up to join this community
I'm not able to purchase agar-agar (yet), so is there a rule for replacing the quantity? I've seen a recipe with 0,5 spoon of agar-agar for 1 spoon of gelatin. Is that the usual proportion?
Additional: is there a difference in treatment to activate the agar-agar or gelatin?
The difference between activating them is important if you want to use gelatin instead of agar. Gelatin is made of proteins and peptides and agar is a polysaccharide.
Gelatin should not be boiled, because it breaks down. Agar needs 95 deg C to dissolve, so usually it is simply boiled. This means, that if your receipe calls for boiling the agar with stuff you want to gel (e.g. fruit), you have to add gelatin later, when all the boiling is finished, but the mixture is still hot enough to dissolve the gelatin.
Also, agar will work on some fruit, that prevent gelatin from geling, like pineapple or kiwi. If you want to use these fruit with gelatin, you have to boil them (or so they say - I have access to agar, so I never tried gelling boiled pineapple with gelatin).
Oh, and about the proportions: 1% agar as stiff as a jelly bear, 0,5% agar is as stiff as a normal jelly. One teaspoon agar weighs 3g, so it will make about 600ml of a jelly.
"Texture" the hydrocolloid recipe collection says the typical concentration of agar agar is:
How much gelatin you need depends on the bloom (strength) of your gelatin. Page 82 tells you how to convert measurements from one bloom strength to another.
