Diacetyl "is also created naturally in fermented drinks like beer, and gives some chardonnay wines its buttery taste, according to the study."
"The makers of some wines, such as chardonnay, deliberately promote the production of diacetyl. . ."
At a certain level diacetyl smells like rancid butter and is considered a wine fault.
Any and all thoughts on this subject are welcome, but I thought this report worthy of your consideration.
None of the above rather obscured labels implies that these wines have any diacetyl in them, but are used as a broad headline announcement of a generic product under review.