I don't like when they say yucky either, especially if they haven't tasted it!

I say, "5LM made this for you and it took a lot of time. It's not nice to say yucky. That's rude. It's yummy stuff (and then if it applies, I point out what's in it that they do like). I want you to try it and then if you still don't like it, that's fine."

I can usually get my kids to take 1-3 bites at least and then if they like it, they finish and if they don't, they finish the other food or wait patiently for their dessert (fruit)

I have one incredibly picky eater and one who can be picky. They're both 3.5 and will try to say yucky too. This has decreased though after multiple days (months? Lol) of saying what I do.