Fussy eaters

The aged dog has now decided he does not like his expensive vet approved for old dogs pellets.
Mum thought it was due to his teeth so she started to crush them - ate some but not pressed - we then tried soaking in water - still not impressed - if the soggy muck resembled a pellet in any shape or form it was pushed to one side
Now mum is cooking up chicken and rice to feed him - he has now decided that he will only eat the pellets if they are dropped onto the floor 1 by 1 as if they are a treat - however he is still spitting some out - they must taste different even though they look the same