Pozol is a traditional drink from southeast Mexico – especially Tabasco and Chiapas – made from nixtamalized corn dough that’s shaped into balls and left to ferment, then mixed with cold water just before drinking. It’s non-alcoholic, thick, refreshing and gets more sour the longer the dough ferments. With cacao ground into the dough it becomes pozol de cacao (also called pozol negro); without it, pozol blanco. It’s a pre-Hispanic Maya food still drunk every day in the region and sold in markets and on the street (Robledo-Márquez et al., 2021).
How Pozol Is Made
- Nixtamal: dried corn is cooked in lime (calcium hydroxide) water, rinsed and coarsely ground into dough. Nixtamalization also makes the corn’s niacin available, which is why corn-based diets built on nixtamal don’t cause pellagra.
- Balls: the dough – with toasted, ground cacao for pozol de cacao – is shaped into balls and traditionally wrapped in banana or other leaves.
- Fermenting: the balls are left at room temperature for anything from half a day to several days. Fresh pozol is mild and sweet; pozol agrio (sour pozol) has fermented longer.
- Serving: a piece of dough is dissolved in cold water, sometimes with sugar or salt, and drunk straight away – traditionally from a jícara (gourd bowl).
The Microbes
Pozol is one of the most studied traditional Mexican ferments. Lactic acid bacteria dominate: in a 2023 metagenomic study that sampled pozol over 48 hours, Streptococcus was the most common genus throughout, within a core of 25 abundant genera, and genes for making amino acids and vitamins increased during fermentation (López-Sánchez et al., 2023). Weissella confusa is also common (Hernández-Oaxaca et al., 2021). Unusually, free-living nitrogen-fixing bacteria (Kosakonia, Klebsiella and Enterobacter) have been shown to fix nitrogen in the dough, which may help explain pozol’s reputation as a nourishing food (Rizo et al., 2020).
Is Pozol Safe?
Sourness doesn’t make pozol automatically safe. Researchers isolated 73 E. coli strains from pozol dough at 6 and 48 hours of fermentation, when its pH was 6.7–4.7 and 4.7–3.7; some belonged to diarrhea-causing serogroups and carried virulence genes, and they survived the acidity (Sainz et al., 2001). At home:
- Work with clean hands and equipment.
- Use boiled and cooled or bottled water, both for the dough and for serving.
- Keep the dough covered while it ferments.
- Discard dough that smells rotten rather than sour, turns slimy or grows fuzzy mold.
How Pozol Is Drunk
- Pozol de cacao: the most popular version in Tabasco – bittersweet, often with a little sugar.
- Pozol blanco: plain corn, sometimes with salt and chili, or with sugar.
- Pozol agrio: longer-fermented and distinctly sour.
Other corn and cacao drinks: Oaxaca’s tejate, Jalisco’s tejuino, and West Africa’s fermented corn porridge ogi. From central Mexico, pulque is fermented agave sap.