How about vanilla, chocolate and coffee?
(milk shakes etc vanilla ice cream)
For me these were the tastes that persisted the longest.
The loss of taste is not pleasant that is true; consider however that there may be a point where it actually hurts when you have even liquid food in your mouth and eating and even drinking is near impossible! At that point the fact that things do not taste does not seem important any longer.

Taste or no tase he needs sufficent nutrition and hydration.

Best

Markus