Kraft Heinz announced last April that it planned to remove synthetic coloring and preservatives from the recipe of its popular macaroni and cheese.
But there was some backlash from consumers who wanted the recipe to be left alone.
Because of this, the newly merged Kraft Heinz company decided it would make the changes without making a big deal about it, opting against an ad campaign or promoting the new ingredients on the front of the box. It made the switch in December. Since then it has sold more than 50 million boxes.
It looks as if nobody even noticed the difference.
In the new recipe, artificial dyes including "yellow 5" and "yellow 6" were replaced with paprika, annatto, and turmeric. Artificial preservatives were also removed.
The experiment has become the focus of Kraft Heinz's new ad campaign, created by the ad agency Crispin Porter & Bogusky. It launches Monday and presents the message: "It's changed. But it hasn't."
Kraft Heinz is calling this the "world's largest blind taste test" -- even though the correct ingredients were displayed on packaging at all times.
The new ingredients will now be more prominently displayed on the front of the box, Kraft Heinz told Business Insider.
"As we considered changing the ingredients of our classic Blue Box, we did so knowing we had to maintain our iconic look, taste, and texture," Gregory Guidotti, vice president of meals at Kraft Heinz, said in a press release. "We'd invite Americans to try our new recipe, but they most likely already have."
Kraft Heinz had released a limited number of promotional boxes of the new recipe (with the pasta shaped like "Star War" characters) back in June. Testers from The Huffington Post said they could not taste much difference between the two recipes.
The recipe change came after Kraft Heinz was under growing pressure from consumers to remove the artificial dyes in the product. A Change.org petition "Kraft: Stop Using Dangerous Food Dyes in Our Mac & Cheese" amassed 365,806 signatures.
More from Business Insider: