This is EXTREMELY easy to get once you've unlocked the "Chain Donuts" treat in adventure mode. Normally, you only have about 4 seconds between each group to keep the chain going, but with Chain Donuts, you get around 15 seconds. And since a hint pops up at about 10 seconds. you shouldn't have any trouble getting a chain of 30. Just make sure you don't complete the goal, and don't rely completely on the hints as you will run out of time.
Also, this is even easier once you've unlocked the ability to use 2 treats at once and earned the "Color Minus Jelly" treat. It makes one color besides your own character's show up less often. That helps you avoid making chains with that color and keeps you from completing your goal too soon.