McDonald's came under fire in the 2010s for using "pink slime" in its hamburgers, but what does that even mean, and why was it such a hot topic?

Pink slime refers to small cuts of fat and lean beef treated with ammonium-hydroxide and processed until they melt together into a paste. This paste can be formed into any kind of meat-like product.

In the reporting by ABC's Jim Avila, the term “pink slime” was used 137 times, as he described the process which creates it. The beef trimmings are placed in a centrifuge in order to separate ...

Claims that McDonald's uses "pink slime" as meat fillers are making the rounds again on social media. "McDonald's hamburgers are only 15% real beef," reads one widely-shared photo attributed to ...