How to make shelf-stable chocolate milk? Based on online reading, it seems like decreasing PH to &lt; 4.5 is the way to reduce spore-former activity.

Is it possible to decrease the pH of milk without significantly affecting its taste and not letting it curdle? 

I have thought about using an emulsifier to potentially prevent curdling, and am thinking about various kinds of acid (gluconic/lactic) that may be less strong in taste than citric. Any suggestions?
The major protein in cow's milk, casein precipitates at pH 4.6. It matters very little which acid you use to get to 4.6, casein will still precipitate. pH 4.6 is about the same acidity as canned beets, a food not known for its tartness, so you won't achieve a very sour flavor before things start curding up on you.
Adding emulsifiers could help some with the isoelectric precipitation, but emulsifiers have flavors too, and you'll have to add them at a not insignificant fraction of the protein (casein) concentration.

For shelf stable chocolate milk, I'd go with a mix of powdered milk and cocoa powder; just add water. All the storebought room temp chocolate milk products I've seen are ultrapasturized or similar.