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.
More top news
A rogue trader has been jailed for ripping off a Birmingham pensioner with a huge bill for work that a surveyor described as "appalling".
Sir Paul McCartney has announced his first UK shows in three years including in Birmingham.
The grandmother of a toddler killed by his drug addict mum said she hopes she “rots in hell” as she starts a six-year sentence.