There was an interesting article over on ScientificAmerican.com site …
There is a reason cats prefer meaty wet food to dry kibble, and disdain sugar entirely
By David Biello
Our feline friends are only interested in one thing: meat (except for saving up the energy to catch it by napping, or a round of restorative petting) This is not just because inside every domestic tabby lurks a killer just waiting to catch a bird or torture a mouse, it is also because cats lack the ability to taste sweetness, unlike every other mammal examined to date.
The tongues of most mammals hold taste receptors—proteins on the cellular surface that bind to an incoming substance, activating the cell’s internal workings that lead to a signal being sent to the brain. Humans enjoy five kinds of taste buds (possibly six): sour, bitter, salty, umami (or meatiness) and sweet (as well as possibly fat). The sweet receptor is actually made up of two coupled proteins generated by two separate genes: known as Tas1r2 and Tas1r3.