Not necessarily! Due to chemical reactions, certain foods are sweeter, less bitter, and so forth when cooked. (e.g. onions caramelize, glucosinolates [0] in kale leach out when blanching)

Evolution already predisposed us to like sugary foods (e.g. fruit) and dislike bitter ones [1].

[0] https://en.wikipedia.org/wiki/Glucosinolate

[1] https://en.wikipedia.org/wiki/Bitter_taste_evolution#Toxins_...