On Tuesday, the fast-food giant announced that it will offer fresh beef rather than frozen patties in some burgers at thousands of restaurants.

The company first announced such plans early last year, and the fresh beef will appear in about 3,500 restaurants starting Tuesday.

The company, which has relied on frozen beef patties since the 1970s, said the fresh beef will be used when Quarter Pounders and “Signature Crafted” burgers are ordered. Other mainstays like the Big Mac and the double cheeseburger will stick to frozen patties.

The fresh beef will be in Atlanta, Charlotte, Memphis, Miami, Nashville, Orlando, Raleigh and Salt Lake City Tuesday, officals said It will then roll out to most U.S. McDonald’s by May.

The change is the latest by the Oak Brook, Illinois-based company to improve its image as more people shun processed foods.