ISI whip espumas and mousses? in Pastry & Baking Posted July 15, 2011 What texture are you after? I've been using my iSi Gourmet Whip for quite a while with great success. You have to make sure you shake your iSi VERY, VERY vigorously to mix your mixture and the NOS before dispensing it. I normally use heavy whipping cream, sugar and/or honey, and fruit puree for flavoring. I had problems the first couple of times I used my iSi, with the mousse coming out very runny. No problems after I started shaking the iSi very vigorously before dispensing.