According to an article in The Atlantic (http://www.theatlantic.com/issues/2001/01/schlosser2.htm), a Burger King milkshake contains the following:

"A typical artificial strawberry flavor, like the kind found in a Burger
King strawberry milk shake, contains the following ingredients: amyl
acetate, amyl butyrate, amyl valerate, anethol, anisyl formate, benzyl
acetate, benzyl isobutyrate, butyric acid, cinnamyl isobutyrate, cinnamyl
valerate, cognac essential oil, diacetyl, dipropyl ketone, ethyl acetate,
ethyl amyl ketone, ethyl butyrate, ethyl cinnamate, ethyl heptanoate,
ethyl heptylate, ethyl lactate, ethyl methylphenylglycidate, ethyl
nitrate, ethyl propionate, ethyl valerate, heliotropin,
hydroxyphenyl-2-butanone (10 percent solution in alcohol), a-ionone,
isobutyl anthranilate, isobutyl butyrate, lemon essential oil, maltol,
4-methylacetophenone, methyl anthranilate, methyl benzoate, methyl
cinnamate, methyl heptine carbonate, methyl naphthyl ketone, methyl
salicylate, mint essential oil, neroli essential oil, nerolin, neryl
isobutyrate, orris butter, phenethyl alcohol, rose, rum ether,
g-undecalactone, vanillin, and solvent. "