David Seeckts, Head of Manufacturing Midlands at Premier Foods said the 511 jobs were going at Birmingham because the firm lost a significant bread contract for 2013 and because of general competition and the nature of the industry.
The Birmingham site opened in 1964. There are 323 production jobs and 188 in distribution.
The plan is for the closure to go ahead by the second quarter of next year.
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John Rowlands died in the attacks in 1974 - his son Paul is among victims' families calling for an inquest into their deaths to be reopened.
It's currently the biggest killer of men under 45 and men are three times more likely to take their own life than women
As the families of 21 people killed in the Birmingham pub bombings ask for a new inquest, here is a timeline of the key events.