In a small pot add the water and gelatin. Over medium heat let it cook for about 2 minutes or until the gelatin dissolves.
Place the tangerine juice and condensed milk in a blender and blend for about 2 minutes. Add the dissolved gelatin to the blender and blend for 1 minute more. Add the tangerine zest and set aside.
In a medium bowl, using an electric mixer, beat the heavy cream for about 3 minutes. Fold the whipped cream into the tangerine mixture.
Using an electric mixer beat the egg whites and sugar in a clean bowl until stiff.
Add half of the egg whites to the mixture, gently folding to incorporate them. Don't overwork the mixture. Add the rest of the whites and fold the mixtures together.
Spoon the mixture into individual serving glasses or bowls and refrigerate for about 5 hours or overnight.
Notes
*For serving the mousse, you can use small glasses, martini glasses, small bowls or small coffee cups.*Esponjado needs to set in the refrigerator for at least 3 hours before serving, so plan accordingly.*This mousse can be made up to 1 day ahead. Cover well with plastic wrap and keep in the refrigerator until ready to serve and add whipped cream right before serving.