Beside lecithin, some kind of sucrose ester FA, whey protein, do you know some kind of emulsifiers that are able to produce a long-term stable O/W emulsion ?
CMC ( Carboxymethyl Cellulose ) is used in food under the E number E466 as a viscosity modifier or thickener, and to stabilize emulsions in various products including beverages, yoghurts etc.
for further reference you could see http://celluloseether.com/sodium-carboxymethyl-cellulose-cmc/
You can use Quillaja Saponin as a natural emulsifier. There's a lot of work nowadays on quillaja saponin and other biosurfactants on its application in food and beverage industries.
For further information, you can check this review.