Since I have never seen a label on a packet of mince that states it contains preservative, I presume no one uses it?
You can gas flush meat so it stays red longer. Depending on the gas(es) used it does have a preservative effect.
I'm not sure whether gases used in this way have to be listed as ingredients.
For example bags of sliced apples are packed in nitrogen flushed packaging. This displaces the oxygen and stops them browning, but you won't find nitrogen in the list of ingredients.
It's not the same as MAP, as the function isn't to increase shelf life or modify ripening characteristics as in fruit etc.
The function is solely to make the meat look better than it actually is - and this is actually based on lack of consumer knowledge of what fresh meat looks like, as it's not pink/red unless I expect it was cut up within seconds of slaughter.
IMO it's controversial for good reason, as even if small there is some risk (that it masks food spoilage at least) and no benefit - except for marketing. They should have to disclose it the same way as food colorings.
From my experience, Pac n Save and new world still wrap meat in gladwrap. The only supermarket I have seen that have the sealed ones is countdown, although I have no idea if they are using the gas in the packets or not. Consumers though should be told, so they can make informed choices. The problem is our laws in NZ get dated quickly.. I wouldn't have known about this unless I watch target a few years ago when they were testing the mince in supermarkets and butchers.