It's an odor so strong, so putrid, that some people near the Grafton/Millbury line in central Massachusetts called police last month, thinking there might be an emergency.
"It smells like burnt toast, but like rotten," said Leighann Gagnon of Grafton.
"We were actually searching in the area for any dead livestock," Kelly Paquin of Millbury said.
"We couldn't even leave our house without gasping. It was nasty," said Michelle Larose of Grafton.
Get Boston local news, weather forecasts, lifestyle and entertainment stories to your inbox. Sign up for NBC Boston’s newsletters.
Sign up for our Breaking newsletter to get the most urgent news stories in your inbox.
But it was no emergency -- just tofu.
"What we found out over the last couple of weeks is that some of our food products smell a little bit more than others, and particularly the tofu was a little smellier than what we were expecting," FeedBack Earth CEO Alison Greenlee said Thursday.
FeedBack Earth opened up on Creeper Hill Road in Grafton about a month ago and began processing food waste that would otherwise end up in landfills into food for livestock.
"We take in food waste," said Greenlee, "whether it's from manufacturers, distributors, grocers. We mush it and turn it into a high-quality animal feed."
But Greenlee says they didn't anticipate that the natural smell of the soy in the tofu would permeate the neighborhoods like it did when it was processed in the plant.
So they immediately stopped processing tofu and installed a deodorizing system.
"This is a system that basically sprays a neutralizing agent into our stacks that neutralizing agent breaks down the smell that's being emitted," Greenlee said.
And as that new system undergoes testing with the DEP and Board of Health next week, neighbors are hopeful the stench will be gone for good.
Larose said she was "going to give them the benefit of the doubt and a little time to work this out."
Gagnon said, "I fully hope that they get to continue what they're doing, and that we get to live without the smell."
Testing of the deodorizing system was scheduled for Monday at around noon.