Yes, many of the food items have definitely increased in AH price. This likely reflects the fact that a lot of food items (in particular the basic white recipes) received big changes that made them much better. Many were almost useless prior to the update, but now they've been renewed and are more valued/desirable.
For those who still claim that the cooking skill was 'nerfed', I think this shows that they are wrong. Cooking has now become far more profitable than before, and I find it to be a viable source of income. Your guess of 20-30% is an underestimate - prices have gone waaaay up. For whites, I can easily get 1k+ gold per unit, whereas before I could barely sell a stack of 30 for a few thousand.