The Peanut M&M was in trouble. It was the early 2000s, and complaints about rancid nuts were piling up at Mars headquarters in McLean, Va., so fast they had outpaced the combined consumer complaints about Snickers, Twix and even the company’s extensive dog food line.

So the world’s largest confectionary company went hunting for a new peanut to solve the problem.

Plant breeders had discovered a genetic mutation that produced peanuts with plenty of monounsaturated fat, like the kind found in olive oil. That meant they were healthier and less likely to turn rancid. It was a start, but Mars — a company that refers to the peanut as its “hero ingredient” — needed more.

They wanted a peanut that was perfectly symmetrical with sweet, roasted notes. It had to stay crunchy inside a ball of chocolate, and have a skin that kept it from splitting and was a touch bitter to balance the sweetness. It had to grow so well in the Southern peanut belt that farmers would be willing to switch out their tried and true seeds for something new.

Peanut researchers at the University of Georgia got to work and created the Georgia-09B, a runner peanut that did everything the candy maker wanted. By 2017, Mars was using nothing but high-oleic peanuts in its M&Ms, most of them Georgia-09Bs.

“Since then, customer complaints have reduced by over 90 percent,” said Peggy Tsatsos, who leads research for the Mars nut science team.

Now, with $3.5 million from Mars, scientists at the university’s Wild Peanut Lab are trying to help Mars out of another jam.