McDonald's is making a huge change to its burgers that franchisees aren't going to be happy about

McDonald's is making a big change to its burgers.

The fast-food chain announced Thursday that its quarter-pound burgers will be made with fresh, instead of frozen, beef at the majority of its restaurants by the middle of next year.

McDonald's has been testing its fresh additive-free burgers that are cooked to order at 325 restaurants across Oklahoma and Texas over the last year.

But some McDonald's franchisees have warned fresh burgers could be a food-safety disaster waiting to happen.

A 2016 survey from Nomura found that two dozen McDonald's franchisees warned that introducing fresh beef patties nationwide would slow down service and expose the chain to new food contamination risks.

"I have major concerns over food safety and our lack of ability to serve a large number of customers quickly," one franchisee wrote.

Another wrote, "If we do not handle the meat perfectly there is the opportunity for bacterial invasion of our product."

These operators fear that they could face an E. coli outbreak similar to the one that affected Chipotle restaurants in 2015. The chain's sales plunged by as much as 30% at the time and its reputation is still damaged by the scandal.

Fresh beef will also mean big changes in terms of how restaurants are run.

"It would be a massive learning curve for our managers and crew," one franchisee wrote. "No doubt the biggest change in McDonald's history. Would be a huge distraction from our 'turnaround.'"

McDonald's has made considerable changes to its menu in the past two years. In 2015 the company said they would use only cage-free eggs by 2025 and committed to using chicken that had not been treated with antibiotics also used on humans.