A highlight of my recent visit to Costa Rica was seeing first-hand how the indigenous Bribri people there prepare a molded corn starter for making chicha, a corn-based alcoholic beverage. Chicha is most famously prepared in the Andes mountains of South America by chewing corn in order for the corn to become saturated with salivary amylase enzymes, which break down starches into simple sugars fermentable into alcohol. I have made chicha in this way and published information on how to do this in my books Wild Fermentation and The Art of Fermentation. I had heard from travelers to the Andes that much of the chicha available there today is produced not by chewing corn but instead by malting (sprouting or germinating) corn, as barley-based beer is made. Germination also produces enzymes that break down starches into simple fermentable sugars. Then, a few months ago, when I first met Costa Rican environmental and seed activist Fabian Pacheco, he told me about this chicha made using a molded starter.

There are the three ways in which people around the world break down complex carbohydrates into simple sugars to ferment into alcohol: malting, molds, and chewing. Each of the three methods accomplishes the job. Chewing is generally regarded as the most ancient method, in contemporary use in a few different regions that I have heard about, scattered around the world. The Western tradition of beer making relies on malting, as do African sorghum beers and some Central and South American corn beers. Molds are used throughout Asia, in varied forms with names including chu, koji, marcha, nuruk, ragi, and nearly infinite local variation. Though the use of molds to make alcoholic beverages (primarily Aspergillus molds, but the traditional mold cultures are generally biodiverse) is widespread across Asia, I had never heard or read of their use in any tradition elsewhere. That is, until I met Fabian and he told me about the use of molds by the Bribri people near the Caribbean coast of Costa Rica for making their version of chicha. Fabian invited me to come to Costa Rica and took me to meet his Bribri friends, who showed us how they make this molded corn starter that they call oko in their language, and is known in Spanish as mohoso, which translates as “moldy.”

Fabian brought me to Finca Loroco, a diversified organic farm and educational center, run by his Bribri friends. The oko was already in process, being made by Mauricia Vargas, the mother of the family, in keeping with tradition around the world in which women have been the brewers. As Mauricia explained it to me, dried kernals of (starchy) corn had been soaked in water for three days. Just before our arrival, the soaked (and thus already fermenting) corn was ground into a thick paste, like a masa dough for tortillas or tamales. We participated in the next step, placing handfuls of this dough into large leaves of a plant they called bijawa (genus Calathea). Each mass of dough was wrapped like a tamale, except in two leaves. The technique was to fold the stacked leaves in half, in order to break their spines in the middle, then form the mass of dough into a rectangular shape on the stacked leaves, roughly 6 inches/15 cm high by 3 inches/7.5 cm wide and ½ inch/1 cm deep. (I did not measure, these are my estimates, and the masses varied quite a bit in size.) The important thing is that the mass be small enough to fold the leaves around them and completely enclose them.

Dough made by grinding soaked corn, bijawa leaves for wrapping it, and cooked, wrapped corn masses.

Mauricia Vargas wrapping corn dough in bijawa leaves for making oko.

The corn dough wrapped in leaves were then cooked in a big pot, most of them covered with water, but the ones at the top steamed rather than boiled. They were cooked for about an hour, then removed from the pot, and left to spontaneously ferment and mold. We did not stay for the entire fermentation period, but as Mauricia explained it to us, the wrapped corn is left undisturbed for four days. On the fifth day, the leaves are opened and the corn masses are removed. Then the leaves are turned over and the corn masses are rewrapped, with what had been the outer surfaces of the leaves in contact with the corn mass. This brings different leaf surfaces into contact with the corn mass, exposes everything to air (molds need oxygen), and seems to help to evenly distribute mold formation. After four more days, the mass is partially dried in the sun, then rewrapped, again flipping the leaves to vary surface contact. Finally, after four more days, the moldy masses are dried in the sun and ready to use or store until use.

Wrapped corn masses cooking on the fire.

Mauricia Vargas and her family, along with Fabian Pacheco, my wonderful host in Costa Rica who took me to meet them.

I participated in the initial wrapping stage only and was sent off with a couple of the wrapped corn masses to age as they described. When I first examined the corn masses after four days, mold growth was patchy. By color and by smell, I could recognize some of the mold as Aspergillus mold like those I have grown many times on rice and barley to make koji. But it showed green mold as well, indicating more than a single type of mold. Four days later, mold covered most, but still not all the surface. Some of the molds were long and hairy and clearly were sporulating. I did not remain in Costa Rica long enough to complete the process or make chicha with the oko, nor did I dare try to bring it home with me, to complete the process or send it to a lab for analysis.

Molds growth after four days.

Mold growth after nine days.

Even in this one family, there are many ways of making chicha. Most are made without the moldy oko starter. We had delicious (and strong) chicha made by removing the steamed and cooled corn masses from the leaves (without the molding process), mixing them together into a paste in a bucket, allowing this paste to ferment in a solid state for several days, then adding water and sugar and allowing the liquid to ferment for a few more days. We were also served a chicha made by adding steamed bananas to the corn paste, allowing that to ferment in a solid state, then mixing that with water immediately prior to serving. They also described chicha made with cacao and corn. Clearly chicha is not a single uniform product but rather a range of corn-based beverages, some only mildly alcoholic, others stronger. The chichas prepared without the moldy oko require sugar or bananas for fermentable simple sugars; the oko is necessary only for chicha made from just corn and water, so that the amylase enzymes from the molds can break down the starchy corn into fermentable sugars.

Due to the fact that I was not there long enough to see the process in its entirety, along with the limitations of our communications and translation, this is certainly not a comprehensive or definitive account. But because nothing (that I have come across in the English language literature) has been written about this, and because of its apparent uniqueness in the Western hemisphere, I thought it was important to share this information, incomplete as it may be. Was this practice the result of an accidental discovery, as so many fermentation processes are, with similar molds developing on grains here as across Asia? Or was there perhaps some past Asian influence here, long forgotten? The origins of fermentation practices are always shrouded in mystery. But over and over we see patterns repeated, with microbial phenomenon manifesting similarly (and at the same time uniquely) in disparate locations. Molded grains for alcohol in Central America is very exciting.