20 jobs have been put at risk at the Colman's mustard factory in Norwich as part of a review by parent-company Unilever.
According to the GMB union, jobs could be lost to Europe amid plans to consolidate its dry soup production with a factory in Germany.
The factory – based at Carrow – currently employs 140 staff. It is believed process workers are being targeted in the review.
Mustard production at the site dates back to 1865, with wholegrain and English mustards currently manufactured there, along with the Colman's range of sauces, powdered condiments and Jif Lemon.
Colman's is one of the oldest existing food brands, founded by Jeremiah Colman in 1814, who produced mustard from a mill in Bawburgh before shifting production to Norwich.
Unilever is one of the world's biggest owners of consumer brands with a portfolio of products including Dove and Flora.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here