It's about sustenance, not pleasure. Penguins can't enjoy or even detect the savory taste of the fish they eat or the sweet taste of fruit. A new analysis of the genetic evidence reported in the Cell Press journal Current Biology on February 16 suggests that the flightless, waddling birds have lost three of the five basic tastes over evolutionary time. For them, it appears, food comes in only two flavors: salty and sour.
Many other birds, such as chickens and finches, can't taste sweet things either. But they do have receptors for detecting bitter and umami (or meaty) flavors.

Gentoo penguin. Credit: Jianzhi 'George' Zhang