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Yeasts of Zimbabwe’s Opaque Beers

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Zimbabwe-beer

The Republic of Zimbabwe is a country in Southern Africa, bordered by South Africa, Botswana, Zambia and Mozambique. While there are several brands of commercial light, lager-style beer available in Zimbabwe — Zambezi, being the “national beer of Zimbabwe”[1] — there is a lesser known style (well, in America at least) of traditional fermented beverage … murky, and opaque. It is known by various names, including chikokiyana[4], doro rematanda or chibuku, muchaiwa, but often called “scud” or “shake-shake” in Zimbabwe. Due to the dizzying number of names, we’ll just refer to it as opaque beer.

The process of making opaque beer in Zimbabwe is generally “includes the cooking of a cereal
meal, souring, mashing, straining and alcoholic fermentation for seven days”. Millet malt is the grain opaque beer is usually fermented from, though occasionally sorghum or sprouted maize is used[2]. Some formulations include milk[4].

Opaque beer is traditionally a home-brew, but some commercial examples are now on the market. SABMiller even produces versions sold under the names Chubiku and Super-Chibuku, which are sold in paper cartons or brown plastic bottles[3].

Earlier this year, researchers from South Africa and the UK published a paper about the yeast strains used in these traditional beers. They collected beer samples from twelve different rural households throughout Zimbabwe. They were able to identify five different species of yeast present among the beers: Saccharomyces cerevisiae (the standard brewers yeast), Issatchenkia occidentalis, Kluyveromyces marxianus, Sporobolomyces holsaticus and Candida glabrata. These are wild fermentations, with the yeasts and bacteria coming from both the malt, and from the clay fermentation pots used in previous brews. The table below shows what yeasts were found and the associated fermentables used in each brew.

Beer sample Fermentables used Yeast identified
1 Maize meal and bulrush millet malt Saccharomyces cerevisiae
11 Finger millet and bulrush millet malt Saccharomyces cerevisiae
2 Maize meal and bulrush millet malt Saccharomyces cerevisiae
5 Maize meal and sorghum malt Saccharomyces cerevisiae
6 Maize meal, bulrush millet malt, and sorghum malt Saccharomyces cerevisiae
8 Maize meal and sorghum malt Saccharomyces cerevisiae
13 Maize meal, finger millet malt, and bulrush millet malt Candida glabrata
2 Maize meal and bulrush millet malt Issatchenkia occidentalis
12 Finger millet meal and malt Issatchenkia occidentalis
7 Maize meal, bulrush millet malt, and sorghum malt Kluyveromyces marxianus
6 Maize meal and sorghum malt Sporobolomyces holsaticus
11 Finger millet meal and malt Rhodotorula
8 Finger millet meal and malt Rhodotorula
2 Maize meal and bulrush millet malt unidentified

Table 1. Yeast identified in opaque beer samples from Zimbabwe.

You can see that while the familiar Saccharomyces cerevisiae dominates the list, but several other yeasts are present in many of the brews — unfortunately, none of which can currently be found at a home brew supply shop.

Of course, as an adventurous brewer you might be wondering, “can I make one of these at home?”. Of course you can. Here’s BrewSession’s own recipe:

Zimbabwean Chibuku
1 gallon batch

ingredients
0.7 lbs (318 grams) Maize (corn) meal
0.7 lbs (318 grams) Millet malt
1 ounce (30 grams) Sorghum flour

method
Combine 1.25 gallons (4.73 liters) water with the above ingredients in a kettle on the stove. Heat to 160°F (70°C) and hold for one hour. Let sit overnight to cool and sour. It should be kind of like a thin porridge. After 24 hours boil the mixture until you have reduced it to 1 gallon (3.8l). Pour into a 1 gallon jar. Add yeast. Cover top of jar with aluminum foil. Let ferment for up to 5 days @ 65°F (18.3°C). Before drinking, strain it through a coarse cheese cloth or colander into a serving/drinking vessel. It is drunk while actively fermenting. Drink within 4-9 days of start of fermentation.


References

1. Beer in Africa. Wikipedia. Retrieved March 13, 2015, from http://en.wikipedia.org/wiki/Beer_in_Africa

2. Misihairabgwi, J. (2015). Characterisation of yeasts isolated from traditional opaque beer beverages brewed in Zimbabwean households. African Journal of Microbiology Research, 9(8), 549-556. Retrieved March 18, 2015, from http://www.academicjournals.org/journal/AJMR/article-full-text/A591F4E50761

3. Zalkind, S. (2012, May). Southern Africa’s Beer Boom: a look at the heart of Africa’s beer scene. Beer Advocate, 47-56.

4. http://www.bloomberg.com/bw/articles/2012-03-15/sabmiller-tries-selling-african-home-brew

5. Gadaga TH , AN Mutukumira , JA Narvhus , SB Feresu. (1999). A review of traditional fermented foods and beverages of Zimbabwe. International Journal of Food Microbiology, 53(1), 1-11. Retrieved September 3, 2015, from http://www.researchgate.net/publication/12703525_A_review_of_traditional_fermented_foods_and_beverages_of_Zimbabwe

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