For example I am interested in African dream root, which traditional recipie is making "cold tea", better to say cold foam. Vigorous mixing of finely powdered root.

Problem is that every plant (root) may contain parasites/ and baceteria. Making hot tea (100°C) kills all those possible threats.

Will cooking this root , or at least heating it at 80 °C destroy active ingredients , most of them are saponins.

Did anyone tried BOTH cold tea (foam) and cooked tea and notices and difference from Afrian Dream root

if you get your roots from a slightly reputable source there wont be anything on them to worry about!

Mother nature is far less toxic then the things you buy/eat daily from the grocery store .

Even if you grow them yourself you can spot any fungal infections or parasites with your eyes pretty easily and if you still feel uncomfortable rinsing plants will get rid of anything thats on them.

you could do a high proof alcohol wash if you're really really worried, but I wouldn't be. I love the dream root tea cold infusion. Never had any noticeable problems with my roots.