Mix together the juice and water, remove approx 50 gm and place to one side in a plastic container.
Soak the gelatine sheets in a little water till soft.
Heat the 50 gm of liquid, remove the softened gelatin sheets, squeeze out any water and dissolve in the warm liquid.
Combine all of the ingredients in the bowl of an electric mixer, and whisk for between 20 - 30 minutes, till aerated and stiff.
Use as desired, then leave in the refrigerator to set.