Agar agar- acidity and reduced gelling effect?

Question

I'm doing a little investigation on agar for a school project. I just want to know from those of you familiar with agar, what are some ways to overcome the problem of reduced gelling ability in the presence of high acidity? For example, fruits are acidic, and this reduces agar's gelling ability in fruit-embedded agar desserts. Besides cooking the fruits, what are other ways to overcome this problem?

Thank you for your help!

Answer 1

To overcome the problem with agar gelling when you want to use high-acid fruits, add more agar to your mix or buy canned versions of the high-acid fruit.

Agar is flavorless and becomes gelatinous when it's dissolved in water, heated, and then cooled.   Agar, though, gels more firmly than gelatin, and it sets and melts at a higher temperature--it can even set at room temperature.  

Acids weaken agar's gelling power, so if you're firming an acidic liquid, use more.  Like gelatin, agar will break down if exposed to the enzymes of certain raw fruits, like kiwi fruit, papayas, pineapple, peaches, mangos, guavas, and figs.  Cooking these fruits, though, destroys the enzymes.  If you plan to add any of these fruits to a gelatin salad, it's a good idea to buy them in cans, since all canned fruit is pre-cooked.