The companies said all their microwave popcorn recipes should be changed by January.

But it might take several months for the reformulated popcorn to replace all the older varieties on store shelves.

In August, the Weaver Popcorn Company of Indianapolis announced it had removed the butter flavor diacetyl from all its microwave popcorn varieties.

ConAgra Foods of Omaha, General Mills of Golden Valley, Minn., and the American Pop Corn Company of Sioux City, Iowa, all promised in September to change their microwave popcorn recipes.

———

On the Web:

ConAgra Foods Inc.: www.conagrafoods.com

Flavor and Extract Manufacturers Association: www.femaflavor.org

General Mills Inc.: www.generalmills.com

American Pop Corn Company: www.jollytime.com