Work has begun on building a processing plant to keep part of Colman's Mustard production in Norfolk.
The factory will help produce mustard for Colman's parent company Unilever, which is due to close its Carrow Works site in Norwich after 160 years.
The new plant at Honingham, near Norwich, means local farmers will retain their links with the firm.
Mustard grower Michael Sly said the decision to build a Norfolk factory had been "very important" for them.
Unilever also officially confirmed its 10-year deal with Condimentum, a consortium set up by the English Mustard Growers' and Norfolk Mint Growers' co-operatives, at the site's ground-breaking ceremony.
Mr Sly, chairman of English Mustard Growers' Co-operative, said: "Had Unilever decided this was not viable, we would have had to soul-search how we could fund doing something like this ourselves to keep English mustard production alive.
"It is sad that heritage and legacy that has been there for 150 years in the city is going - but at least it is carrying on locally.
"We've had a very long association with the facility at Carrow and with Colman's - there's been quite an emotional attachment and bond between the growers, Colman's and the factory."
Jon Strachan, from Unilever, said: "We were determined to maintain this historic link between Colman's and the Norwich area."
The new plant will grind mustard seeds into flour and process locally-grown fresh mint for Colman's before the ingredients are sent to the Midlands.
The factory will be the first building constructed on Honingham's Food Enterprise Park after planning permission for the site as a whole was approved in January.
Unilever will switch its operations from Norwich to Burton-upon-Trent in Staffordshire and sites in Germany.
The new factory will provide about 25 jobs, while the current Carrow Works site employs about 100 people.