Production at the two Carriage House facilities on Newton Street in Fredonia and on Talcott Street in Dunkirk was shut down Tuesday when 550 employees voted Monday to strike.
Members of Local 266, National Conference of Firemen and Oilers, Service Employees International Union, manned picket lines in both locations.
"Last night, the union defeated the contract by an almost 2-1 margin," said President Jim Bradley. "The company said it was the final offer."
"The two issues are fair wages and better medical and dental benefits," added Bret Thomas, union grievance representative.
All calls to the company were referred to Scott Monette, the corporate vice president of the parent company, Ralcorp, in St. Louis.
"I have no comment on anything," he said.
The company's facility on Newton Street in Fredonia is the former Red Wing plant and makes jellies, jams, peanut butter and other private label foods. The Dunkirk facility is the former Kraft plant. The corporation moved production of salad dressing and mayonnaise production there from the Baltimore area.
Dunkirk Mayor Richard Frey, a retired executive of Carriage House, made note of the labor unrest during a meeting of the Common Council Tuesday evening.
"I hope both parties can get to the table and resolve the situation shortly," he said. "I am sympathetic and respect both sides. It's been s long time since the city has seen labor unrest."