The 95-year-old monarch was joined by grandson Prince William for her first visit to Scotland since the death of her husband of seven decades Prince Philip in April.
The royal duo visited an AG Barr factory in Cumbernauld to officially open a new processing facility at a factory making Irn-Bru, the luminous orange fizzy drink which is more popular among Scots than Coca Cola.
William joked off-camera that you could "taste the girders," a reference to the company's tongue in cheek slogan, as he sampled some of the drink.
"I'm trying to guess what's in it but that's quite hard," he said as he sniffed a bottle containing the essence of Irn-Bru. "It's a closely-guarded secret."
The queen's visit has been portrayed in the media as part of a charm offensive to help persuade Scots to reject independence should the Scottish government go ahead with plans to hold a second vote on secession.