I gave you the benefit of the doubt and checked. I can't find any instance of any such report. Can you cite a source?
You didn't know? Cannot believe it. Course, they don't exactly brag about it or advertise it.
It is well-known that McD's employs top chefs to formulate their food selections. All of the food is formulated for taste, and cost factors, including the burgers.
For instance the McGriddle breakfast sandwiches---eggs and bacon or sausage between maple-flavored pancakes---a huge seller---was tested and failed for months. Until somebody at the company came across an unusual ingredient----dry maple crystals----and brought them to the chef to use as the key flavor factor.