35+ years ago, I did some advisory work with McDonalds. At that time they were pretty fanatical on quality and consistency. They had traceability on their raw materials that was on a par with M&S and quite precise and comprehensive operating procedures. Indeed I later used some of their HACCP schemes (anonymised ) to produce templates when teaching students. In those days I think they had a lower proportion of franchised outlets and I would say that there was then more variablity in quality between the McDonalds’ franchised outlets than the McDonalds owned outlets.
One of the problems they had was a conflict that they had with cooking times, they wanted an American concept of ‘doneness’ which left the centre of their burgers slightly pink. The problem was with the emerging cold tolerant pathogens with relatively low infectious dose levels ( e.g. Listeria moncytogenes and E. coli 0157). These had become an issue as improving the food chill chain stopped spoilage bacteria from making the food obviously ‘off’ whilst allowing harmful bacteria to continue to grow unnoticed. This was a problem for much of the food industry in the 1980’s and by and large the bigger companies with their more extensive technical support were quicker to respond than small companies.
Their preferred cooking regime for quality was OK if the initial load of pathogens was low but could give problems if there was a higher initial load of pathogens, or if the grill surface dropped a bit low, as could happen at very busy times.
I visited their East Finchley HQ which housed their UK “Burger University” to do some checks for them and also to their Crawley outlet. Checking temperatures in a busy outlet over lunchtime didn’t make me too popular with the manager - fortunately I was backed up with a UK director. In the end I think they increased their cooking times slightly.
I haven’t had a Big Mac for a while but a year or so ago I had a bacon roll when the restaurant where we were staying overnight was closed by a fire and McDonalds was just across the road. It was ok but nothing to write home about. Didn’t like the impersonal ordering system much.