Rwandan scientists develop local yeast for banana wine-makers

https://phys.org/news/2025-01-rwandan-scientists-local-yeast-banana.html

by PaulHoule • 1 year ago

181 80 1 year ago

“The team looked for a fermenting agent that could remain reactive in substances with a temperature of up to 370 degrees Celsius and alcohol of the recommended 16 percent per volume.”

My guess is that the reporter forgot a decimal point and meant 37.0 degrees Celsius. Because finding a yeast that actively metabolizes sugar at 370 degrees Celsius might be somewhat challenging.

aDyslecticCrow• 1 year ago

Yiest that could survive in volcanic geysers is a bit terrifying to think about.

tmoertel• 1 year ago

It turns out that the Yellowstone Supervolcano is actually over-risen bread...

codesnik• 1 year ago

free kombucha!

interludead3• 1 year ago

Still, the research itself is pretty exciting. It’s cool to see traditional methods getting scientific backing

piuantiderp• 1 year ago

This made me snort my coffee, what backing was needed or lacking? Need peer-review to validate them?

johnofthesea• 1 year ago

Optimal temperature for yeast in general is between 25-30C, for grape wine optimal fermentation is usually between 15-20C (white) 20-25C (red).

So 35C is interesting. 350 would be too much even if it was Kelvin.

throw-qqqqq• 1 year ago

Kveik beer yeast often works well far above 35C. Some reportedly tolerate into low 40s.

I don’t know of other yeasts that can do this though.

nxobject3• 1 year ago

Mmm, caramel sweet wine, perhaps?

jojobas• 1 year ago

Especially given glucose decomposes under 200C.

xattt• 1 year ago

New fermentothermal electricity power source discovered!

gp• 1 year ago

370 degrees Celsius? Hopefully a typo

Last time I was in Rwanda I had banana wine. It comes in beer bottles.

I think it’s an acquired taste - I didn’t have the acumen to acquire it myself.

ReptileMan2• 1 year ago

Fruit wines are tasty usually. But the hangover is on the next level.

permo-w2• 1 year ago

depends on the fruit and how many anti-oxidants managed to survive the brewing process

werdnapk2• 1 year ago

All wine is made from fruit.

b800h• 1 year ago

This is because pectin in the fleshier fruits will be metabolised into methanol, which isn't very good for you.

Grapes are less of an issue.

lambda• 1 year ago

The article mentions that it was provided by SciDev.net.

Looking there you find the original article, and it has the correction to the right temperature: https://www.scidev.net/global/supported-content/rwandan-scie...

culi• 1 year ago

The team looked for a fermenting agent that could remain reactive in substances with a temperature of up to 37 degrees Celsius* and alcohol of the recommended 16 per cent per volume.
This article was edited on 29/01 to correct the temperature for fermenting to 37 degrees Celsius.

tiahura• 1 year ago

Certain yeasts used in beer brewing produce an ester that is banana-like, especially when brewed at higher temps. It's often considered an off-flavor.

DFHippie• 1 year ago

Now I'm really curious to taste banana wine.

Banana is one of those flavors that some people love and some people really hate. Others in this category -- lutefisk, kimchi, certain cheeses -- make sense: their distinctive flavor is associated with decay. Why bananas, though?

My grandfather was a banana hater. His observation on the topic: "I hate bananas, and I'm glad that I hate them, because if I liked them I'd eat them, and I HATE them!"

sram1337• 1 year ago

Bananas are a staple food crop in some parts of Africa.

https://en.m.wikipedia.org/wiki/Matoke

cmrdporcupine2• 1 year ago

It took me until my 30s to make the connection that bananas cause me intense headaches. I used to love to eat them, but now won't touch them.

I think I'm fine with them cooked, but not raw.

I don't know the mechanism, but if you do searches on bananas and headaches you will find people prescribing them as a cure for headaches, not the other way around.

btylke• 1 year ago

It could be a latex allergy. Bananas are one of a few fruits that cause latex allergic reactions.

interludead3• 1 year ago

I'm also curious about banana wine… wonder if it leans more toward fresh banana or that overripe, almost fermented taste.

dan353hehe• 1 year ago

If I had to guess, it would be that fermenting bananas into wine makes them taste like they were fermented.

In all seriousness though, I can’t stand overripe bananas. Bleah.

vgrafe• 1 year ago

I went a couple years ago in coutryside Rwanda, where locals brought me to a place where I could have some homemade banana wine, or "Urwagwa" (not sure about the spelling!). That place was someone's house with a few people hanging out and drinking, the wine was served in already-opened glass bottles.

For those curious, it is not very boozy (maybe around 7%-10% abv), but very yeasty - to a point where it kinda numbed my mouth. For those curious the yeast is the dominant flavor, followed by banana. Very earthy taste.

Later on I saw Urwagwa sold in a can at the airport, it was very different, no yeast but bitterness instead. I preferred the homemade one.

quijoteuniv• 1 year ago

The article explains nothing, and has a very suspicious typo. If i heat something organic to 370 degrees i do want it to die :D

interludead3• 1 year ago

Science helping tradition instead of replacing it

sjmulder• 1 year ago

The explanation as to why flour yeast and grape wine yeast are unsuitable is a bit of a tautology. I know little about yeast. Can someone explain why one sort of yeast is not suitable for another use? And why is "sorghum, the traditional fermenting agent of banana wine" unsuitable or not acceptable to regulators?

yial• 1 year ago

Sorghum is acceptable I believe. It’s the fifth most produced crop in the world. It sounds like what might not have been acceptable is using wild yeasts to ferment it.

dluan3• 1 year ago

It's similar to the malting process. Certain ingredients will contain enzymes and other important metabolites that can break down complex sugars into smaller simpler sugars that can be eaten by yeast (glucose, fructose). You need them to get a fermentation started and warmed up.

stubish2• 1 year ago

Even more confusing: "We mixed the fermenting agent with sorghum flour to keep the traditional color and aroma of sorghum, the traditional fermenting agent of banana wine"

So they developed a yeast to replace the sorghum as the fermenting agent, and then mix sorghum in. What has been gained? Does yeast make for a more controlled fermentation making regulation easier? Or just easier to industrialize?

I suspect that using sorghum for fermentation really means using whatever wild yeast happened to be on the sorghum, and the results too variable to regulate for commercial sale or export.

dmurray2• 1 year ago

I suspect that using sorghum for fermentation really means using whatever wild yeast happened to be on the sorghum, and the results too variable to regulate for commercial sale or export.

Definitely this. Sorghum is not a "fermenting agent": it's not an organism that eats sugars and shits out alcohol and carbon dioxide (actually, it's pretty much the opposite). It's just somewhere wild yeast likes to live.

jrflowers• 1 year ago

Different yeasts have different temperature and alcohol tolerance. For example a bread yeast may not continue making alcohol beyond 5-6%, or another yeast may only be productive in a narrow temperature range that’s too warm or too cool for a given application.

amonon• 1 year ago

To add on, different yeasts also vary in their ability to metabolize carbohydrates. In general, a wine yeast will be less able to metabolize complicated carbohydrates than a beer yeast. Beer yeast tends to be more sensitive than wine to alcohol levels. More importantly, it's possible Rwanda lacks any serious brewer's yeast industry that is suitable. Kveik may be able to ferment at both 37C and up to 16% ABV but that's definitely an unusual trait in a yeast and I would not be surprised if they resulting wine was... funky.

metalman2• 1 year ago

bannana wine, just does not work well in.english or bannana beer, or bannana cider, would be interesting to hear the term or terms used localy that might be evocative and perhaps marketable but certain words just dont work together..... like english, and cuisine, ha ha! it is and will forever be english food. rooooll your ooooo's

s0rce• 1 year ago

Sorry, native english speaker here, what is wrong with banana wine?

metalman2• 1 year ago

nothing.....if you can make it work.....but in many native english markets, it wont, cept perhaps the kiddy booze market, where if you mix in enough tuarzine(whatever) and ??? purple blobs of some goo, it will jump off the shelves but as a meal acompanyment, no wait wait, with german desert wines going extinct there could be a market for a desert wine so......go for it, mang!

idunnoman1222• 1 year ago

Normally, you ferment at lower temperatures because your drink will taste disgusting… (there will be terrible byproducts) this article has no explanation as to why this traditional drink suddenly tastes fine with a high temperature yeast other than something about regulators accepting some shit. I imagine that traditionally they they didn’t add commercial yeast… they just opened the top of it and prayed.. and the wild yeast which probably where they live Ferments fine at higher temperatures however, I had to make this all up in my head because there is no fucking information in this entire article and certainly no science and I’m amazed it’s number three. What the is this shit

fmbb• 1 year ago

Normally when you make banana wine?

jerrysievert• 1 year ago

I think you need to try some kveik yeast, that might change your mind on high temperature fermentation: kveik is a Norwegian yeast, somewhat recently (last 25 years) rediscovered but brewed with for centuries, and can handle 37ºC without the byproducts.

declan_roberts• 1 year ago

They've been making banana wine from wild yeast presumably for at least a 100 years or longer. It sounds like the regulators in their country are a PITA and won't get out of the way.

There's a million different strains of yeast but they all do the same thing. If you don't add any yeast it will still ferment with the wild yeast.

collyw• 1 year ago

I was thinking the same. Though wild fermenting works well for small batches, I have no idea of it scales. I was guessing this is a comercial operation if regulators are involved.

dluan3• 1 year ago

Regulation is extremely important, and has been part and parcel of alcohol and wine production since prehistoric times. Besides the health reasons, wine is very easy to cut with synthetic or artificial ingredients, which has important economic and health consequences - hence the use of government bonding for hundreds of years around the world.

But more recently, regulation is vital for setting up geographical indicators for production of items that are locally unique, e.g. Parmesean, Champagne, and the German Reinheitsgebot which are legally protected practices for the reasons in the first paragraph. Being able to identify the specific strains of yeast in this banana wine is a big part for arguing the provenance of it.

stubish2• 1 year ago

You can't create an export market if you product is variable due to your results depending on whatever yeast happened to be used that day.

daurnimator• 1 year ago

Lambic beers prove you can do that

dluan3• 1 year ago

Bananas are notoriously hard to turn into a cleaner wine, mainly because of the fact that most bananas that are not Cavendish have a lot of latex and turn into goop. Most of the places where banana wine is produced (tropics) ultimately also turn it into banana "gin", and there's an incredibly deep and long cultural history of its production, e.g. it's tied to British colonialism in West Africa funded by liquor revenues, regulation was a hot topic of local protests, and drinking bars used to be hotbeds of nationalist agitation. When Nkrumah's CPP took over Ghana, they legalized homemade wine/liquor as a symbol against the gin drinking imperialists (in 1890 a bunch of countries in Brussels banned liquor importation to Africa).

The other much easier to produce wine and spirit comes from palm sugar (akpeteshie in Ghana, toddy in Indonesia), but the time window of when it is fresh and can be consumed is counted in hours, so it's not stable enough as an agricultural product to sell. Banana wine is an easy way to turn surplus calories into surplus cents.

prmph• 1 year ago

But fresh palm wine is now bottled for sale in Ghana at least. I know because I've bought some in Ghana several times. Not sure how they preserve the freshness and prevent further fermentation though.

ginko• 1 year ago

They could pasteurize it or kill the yeast with sulfites like they do with wine.

skirge• 1 year ago

what they want to achieve? Biofuels?

Rwandan scientists develop local yeast for banana wine-makers

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