The Poison We Drink: Detoxifying Cassava by Brewing Masato in South America

masato cassava beer

Cassava may feed the future. Yuca or manioc, other names for the edible root of Manihot esculenta, figure well into a sustainable outlook on food systems in a hotter, drier, more populated world. The Food and Agriculture Organization of the United Nations notes the unprecedented growth of cassava production in recent years. Their 2021 report states that “cassava production has doubled over two decades,” outpacing population growth by a factor of three. With this boom in production, it is important to remember where cassava came from and who figured out how to use it for food first. After all, cassava is toxic to humans, so all credit goes to the native peoples of the Amazon, who have used the root to make food and beer since pre-Hispanic times. 

Why has yuca cultivation been catching on? Cassava requires very little attention to grow. It tolerates heat, grows with little water, and stays fresh underground without a short harvest window. In areas where other crops can no longer survive, the oblong, white-hearted cassava is a carbohydrate bounty. Already, some African governments are mandating that all flour is mixed with a certain percentage of cassava flour. The leaves are also edible and deliver more vitamins and minerals than the pale root.

Protein, however, is lacking. Only 1-2% of a cassava root is proteinaceous, so subsisting on cassava alone causes malnutrition. One way to increase the protein content of the root is through fermentation, which can elevate the nutritional value to around 4%. This fermentation, it turns out, is important for another reason too.

yuca root with wax
Cassava, manioc, or yuca. All are the same thing. Yucca, however, refers to a different plant native to the American Southwest.

For all of its benefits, cassava has one major flaw. It is poisonous. Within the cytoplasm of Manihot esculenta’s individual cells are two cyanogenic glycosides compounds called linamarin and lotaustralin. The plant’s cell walls have an enzyme that breaks these glycosides down. When the root is mashed, chewed, or otherwise broken, the cytoplasm meets the cell wall and the compounds transform into the highly potent hydrocyanic acid. 

The concentration of the toxin varies based on the kind of cassava plant. Bitter plants that grow in more harsh conditions often have the most. These can contain 200 milligrams of cyanide per kilogram of cassava. Only 60 milligrams of cyanide will kill an adult. (Mould) Moreover, the poison is focused in certain areas within the plant. The layer between the skin of the root and its flesh, called the cortex, has the highest concentration followed by the edible leaves. (Falade)

Cyanide poisoning via cassava consumption rarely results in death. There are isolated cases in times of extreme scarcity, or when people unfamiliar with the crop attempt to eat it. On the other hand, long term consumption of the stuff with trace amounts of cyanide can damage the liver, nervous system, and skin. 

brewing with saliva
A drawing in André Thevet's 1558 book on the Americas, Les singularitez de la France Antarctique in 1557 or 1558. The image depicts natives using saliva to ferment.

So why do we eat cassava? Turns out, it isn’t so difficult to get rid of the cyanide–just don’t eat it raw. Steaming, boiling, sun drying, and fermenting all decrease the cyanide present in the tuber to safe and edible levels. The last technique, fermentation, is used in rendering cassava not only edible, but also potable. 

Across the Amazonian basin, in Peru, Brazil, Guyana, Bolivia and Ecuador, indigenous peoples have been using cassava roots to make boozy beverages for a long time. Their particular recipes and techniques vary across space and ethnicity, but most of these beverages have some commonalities. Firstly, many of the yuca beers are made with chewed cassava that introduces salivary enzymes into the fermenting root to help break down starches. Second, most drinks are fermented with lactic acid bacteria, especially Lactobacillus plantarum. (Rebaza-Cardenas) Lactic acid bacterias are known to be hostile towards pathogens like E. coli commonly found in water. Drinking cassava beers also makes staying hydrated safer. 

In order to transform this toxic root into a safe beverage, native peoples put the cassava through a traditional process. Usually, women are the exclusive preparers of these fermented cassava brews. Once harvested, the roots are washed and boiled. The boiled cassavas are then mashed, often in a wooden trough, and put aside for fermentation. It is during mashing that the brewers may chew cassava and spit chunks back into the mash in order to add saliva. Yeasts can be added by pouring in old chicha or cassava beer, but spontaneous fermentation is also used. The fermented mix can be cut with water to make it more liquid and consumed. 

masato cerveza de yuca
Even children will consume slightly alcoholic masato as it is a core part of both hydration and nutrition. From Asier Solana Bermejo, CC BY-SA 2.0 , via Wikimedia Commons

The number of cassava beverages is impressive. The Shawi of Peru have masato. The folks in Guyana make parakari. The vastness of the Brazilian Amazon is home to cauim, caxiri, calugi, and taruba, and yakupa—all made with cassava. Recipes vary and cassava is sometimes supplemented with other plants to add flavor, color, or consistency. Some brewers add sweet potatoes, sugar cane, and even mushrooms called sankuch to the fermenting cassava. (Mayorga) Some brewers roast the root before fermenting. 

Fermented cassava beers have been a lifeline for many. Some communities use these drinks as their primary source of hydration. It can be safer than fresh water. Fermented pulp can be carried on long journeys to mix with water of unknown quality. On top of this, the drink is a source of carbs and energy. 

While the indigenous traditions show the ingenuity of the Amazonian peoples in eliminating cyanide, modern commercial tendencies have also changed the beverage. Peruvians today can drink “cerveza de selva” or jungle beer that is a cheaper riff on traditional masato. Rice flour and cane sugar are added to increase the sugar available for yeast to convert into alcohol and add a sweet taste. Fruits like pineapple can also make a more palatable version. Colombia’s largest beer company Bavaria (and subsidiary of AB-Inbev) launched a new beer called Nativa in 2021 which uses cassava starch as a base and is sold along the Caribbean coast. 

South America is the origin of the cassava root and its fermented derivative, masato. But today, other cultures on different continents detoxify the root via fermentation. West Africans make gari flour from fermented cassava, while Malaysians make the slightly alcoholic dessert, tapai ubi, by mixing cassava with a traditional fermentation starter called ragi peuyeum.

As the world focuses on feeding more people with cassava flour or livestock raised on cassava fodder, let us not forget the liquid options. We can look to the Amazon and find a wide range of intriguing beverages which deliver not only carbohydrates, but also clean water, vitamins, probiotics, and a bit of protein.

Sources Cited

Falade, Kolawole., and John O. Akingbala. “Utilization of Cassava for Food.” Food Reviews International, vol. 27, no. 1, Jan. 2011, pp. 51–83. EBSCOhost, https://doi.org/10.1080/87559129.2010.518296.

MAYORGA, Gabriela Alejandra CHACÓN, et al. “Ancestral fermented indigenous beverages from South America made from cassava (Manihot esculenta).” Food Science and Technology 41 (2020): 360-367.

Mould, R. F. Mould’s Medical Anecdotes : Omnibus Edition. Milton: CRC Press LLC, 2017.

OECD-FAO AGRICULTURAL OUTLOOK 2022 – 2031. https://www.agri-outlook.org/commodities/.

Rebaza-Cardenas, Teresa D., et al. ““Masato de Yuca” and “Chicha de Siete Semillas” Two Traditional Vegetable Fermented Beverages from Peru as Source for the Isolation of Potential Probiotic Bacteria.” Probiotics and Antimicrobial Proteins (2021): 1-12.

 

Tamang, Jyoti P., Koichi Watanabe, and Wilhelm H. Holzapfel. “Diversity of microorganisms in global fermented foods and beverages.” Frontiers in microbiology 7 (2016): 377.

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