"The foil was so tight I could hardly breathe," said one trainee, who accuses his colleagues of smearing permanent marker over his face in a fraternity-style attempt at an initiation, sanctioned by supervisors.
He did not initially report the incident. "I was scared of being fired right away, as I was still on my trial period," he said. Staff apparently also threatened to lock him in a minus 20-degree freezer if he was cheeky again.
The allegations appear in an updated edition of 'Inside Aldi' by former Aldi Süd manager Andreas Straub.
Among the allegations featured in the book are accounts of staff being bullied using rats and subjected to 'psychological terror' for speaking up for their rights. Straub accuses other German supermarket chains of similar mistreatment.
It is Straub's second book about his former employee. The first, 'Aldi, Einfach Billig,' (Aldi, Simply Cheap) which is to be made into a film, accused the company of spying on employees and setting unreasonable performance standards.
Straub told The Local: "There was a culture of fear at Aldi Süd and nothing has changed since the publication of the [first] book. I hope this might lead to some changes."
Earlier this year a former detective told Der Spiegel that the management of an Aldi store in Dornstadt in Baden-Württemberg asked him to install miniature cameras over the lockers in the staff changing rooms.
"I was tasked with reporting all irregularities," the detective told the magazine in January. "So [I had to say something] if a member of staff was working too slowly, or if I heard about them having a relationship with another member of staff, or received other details from their private lives, for example their financial situations."
Aldi has repeatedly denied spying on staff but told Spiegel Online it was "shocked" by the latest allegations and would "do everything" to investigate the reports.
In a statement to The Local, Aldi Süd said: "To our dismay, our internal investigation shows that the incident described does in essence represent the truth.
"We regret this incident in the distribution centre in Mahlberg, which according to our research, took place at the end of 2012/beginning of 2013 and are deeply concerned."