Unions are calling for an urgent meeting with the new owners of Weetabix.
Unite represents more than 110 members, including engineering and technical staff at two sites – Burton Latimer and Corby in Northamptonshire.
The breakfast cereal company Weetabix has been bought by US consumer giant Post Holdings from the Chinese owners Bright Food Group, in a £1.4bn deal announced today.
Unite regional officer Sally Mortimer said:
Some of the UK's best known food brands are made by a company in our region and today they were bought by an American firm for £200m.
Premier Foods, based in Luton, has sold its jams and spreads division - including brands like Hartley's and Sun-Pat, made at its plant at Histon near Cambridge.
But, as our Business Correspondent Matthew Hudson reports, this isn't your typical story of workers' jobs under threat.
Weetabix, the cereal maker based in Northamptonshire has been taken over by a Chinese company.
Shanghai firm Bright Food will take a majority sixty per cent share in Weetabix which will value the giant food manufacturer at £1.2 billion.
Weetabix, which also owns Alpen and Ready Brek, was founded in 1932.
It was family owned until 2004 when it was bought by a Texan private equity firm