The company, which is owned by Food Utopia and has been operating in south Wales for more than 60 years, ended production on Friday (27 January).
Food Utopia said it regretted that it could not find a way to keep the Avana Bakeries site financially viable.
John James, regional secretary officer for the Bakers Food and Allied Workers Union said Avana Bakeries had had “a real family atmosphere”.
“It’s difficult to understand that a business that has been in operation for so long has suddenly come to an end,” he said.
“They are keeping 10 people on for the Cake Academy, which is owned by Food Utopia, but we feel this closure could have been avoided.”
The site had been threatened with closure two years ago when 2 Sisters, which owned the company at the time, launched a strategic review following the loss of a major contract with Marks & Spencer.
The business, which was also previously owned by Premier Foods, was acquired by Food Utopia from 2 Sisters.
Newport councillor Chris Evans told British Baker he was devastated for the workforce at Avana Bakeries.
“They’ve done nothing wrong, apart from be loyal to their employer, from which they have accepted redundancies in the past. They have worked incredibly hard to try and turn the company around,” he said.