Bettina Elias Siegel launched the infamous "pink slime" petition on Change.org.

ANAHEIM, CALIF. — Few things may be scarier for food manufacturers than moms with computers. Lately, a spate of large companies, including General Mills, Nestle, Kraft Foods and Hershey, announced major initiatives to remove controversial ingredients from popular products. Whether these moves were motivated by Internet activism remains unclear, but one woman behind several on-line petitions is championing the efforts.

Bettina Elias Siegel, a Houston-based writer who runs the blog TheLunchTray.com, never thought of herself as an advocate until a petition she launched on Change.org in 2012 generated viral attention. The petition, titled “Tell U.S.D.A. to stop using pink slime in school food,” garnered more than 200,000 signatures within nine days and prompted the U.S. Department of Agriculture to change its policy on using Lean Finely Textured Beef in the ground beef served in schools.

The question posited during a March 5 presentation at Natural Products Expo West in Anaheim was simple: Should brands be nervous about mothers like Ms. Siegel?

“I think they should be nervous, and they are nervous,” said Ms. Siegel, who also launched a 2014 petition on Change.org to remove chicken processed in China from supermarkets and schools. “Up until the advent of the Internet and the tools for activism, I think it’s fair to say the food industry controlled its narrative and had a monopoly on the information about its products. That has totally been upended. We can find out food information far more easily than we could before…

“They certainly have lost some control and are nervous about it.”

Recently, a number of executives, including the Campbell Soup Co.’s Denise Morrison, have acknowledged the clamor of social media and a growing distrust of big food makers. Ms. Siegel’s advice for large brands seeking to avoid negative attention is to exercise risk management.

“There is always that risk now that you’re going to be the one in the crosshairs,” Ms. Siegel said. “As a company, look within and ask ‘what ingredient are we using or what animal welfare practice are we complicit with that could be damaging to our bottom line?’

“Think about that vulnerability and maybe address it ahead of time.”

Nestle’s recent announcement to remove artificial ingredients from candy is one such example, she said.

“There is so much good PR to be gained, and I think this Internet activism shows consumers care so much about transparency and sourcing, so it’s a win when companies can show they’re on board,” she said.