Hundreds of people drank the beer, with dozens found dead in their homes later in the day and others rushed to a local hospital with diarrhoea and severe muscle aches.
A total of 232 people were affected, and 75 died in the incident in the village of Chitima in the northwest of Mozambique.
"The victims were poisoned by the homemade beer which had been contaminated by a toxic bacteria found in the corn flour used to brew it," Ilesh Jani, director of Mozambique's Health Institute, told reporters.
The woman who brewed the opaque beer and several members of her family were among the dead.
Some local media had initially speculated that the beer was laced with crocodile bile, a powerful toxin.
But tests conducted in the United States identified burkholderia gladioli, a bacteria found in the flour as the source of the poisoning.
Cases of similar poisoning from the same potent bacteria have in the past been reported in Indonesia and China, according to Jani.
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