Allow me to jump in with this post from The Art of Drink that discusses using
maltodextrin as substitute for egg whites to thicken your sours.
http://www.theartofdrink.com/blog/2006/01/maltodextrin.php#more
Here's the meat of the article:
"For cocktail purpose’s, we can use maltodextrin to add a smooth silky texture
to drinks, or we can use it to help create a nice stable foam head on a
cocktail. It is also slightly sweet, so we can use it to provide some
balancing sugar to sours and other drinks that use sugar."