I don't know what it is but Sophie has quite the pallett. We discovered that she liked lemons at Boston Pizza back before Christmas. I had a lemon in my water and she kept grabbing for it. I gave it to her to quite her down. I figured that she would hate it then I wouldn't have to worry about it but no. She sucked every last bit of juice out of that lemon. The other day I had limes and I was putting a wedge in my soda and thought I would let Sophie try it. She let out one sour face, then again, sucked all the juice out of it. Is that normal?? I don't think so. She would love me forever if I would let her eat plain ranch or plain ketchup for every meal and lemons and limes for snacks. So strange!