Nearly 1,200 workers at the Heinz Baked Beans factory in Wigan have started a 24-hour walkout.
The action was agreed at a mass meeting on Saturday after a ballot to reject a pay offer of 3.3% this year and 3% the following year.
Members of the Unite union have also begun a ban on overtime.
Heinz said the pay offer was "one of the best in the food and drink sector, the area and the country" and the first year offer equalled 4% "in real terms".
About 1,200 people are employed at the Greater Manchester factory, which produces beans, soups, pasta meals and baby food.
The walkout began at 2150 GMT on Wednesday.