Rising competition has increased pressure on food firms
Hazlewood Foods, one of the biggest producers of convenience foods in the UK, is laying off 379 people at its plant in Dallas Road, Bedford, during the next two years.
Tony Lewis of the Bakers and Allied Workers Union said: "The workers are very, very disappointed and shocked at the closure.
"It will devastate the community and I believe this will be a real hammer blow to Bedford."
Increased competition
The company said there will be no redundancies before January.
Hazlewood Foods said it hoped some staff would be able to relocate to the parent company's new plant on Deeside in north Wales.
The closure will not affect another Hazlewood Foods site in Old Ford End Road, Bedford.
Irish owner
The company has recently announced that intense supermarket competition had made trading conditions "far from easy" and put margin pressures on many of the group's businesses.
The firm cut more than 100 jobs at its pickles and sauce factory in Manchester earlier this year when it transferred production to Selby in Yorkshire.
Hazlewood Foods was purchased for £258m by the Irish company Greencore Group in 2000.
It employs about 11,000 at its production facilities in the UK, Ireland, Germany and France.