Super-Yeast: Why Not?

I would likely suggest Lalvin DV10 as a good high tolerance yeast. As for why hasn't a super yeast been created, probably because higher alcohol concentrations destroy the enzymes needed to continue alcohol production. Concentrated Alcohol is extremely toxic, 0.5% in humans will kill you, but hey some yeasts make it to 18 - 20 % - a pretty amazing feat I'd say.

cheers,
Wrathwilde

The Boston Beer Co (aka "Samuel Adams") developed a yeast strain that has an alcohol tolerance of about 25%. I remember watching a show on the History Channel where Jim Koch was interviewed and he said that it took them something like 10 years to breed that yeast for that high of an alcohol tolerance.

They use the yeast to make Utopias, the most expensive beer in the world (about $140 a bottle) and also the record holder for the highest alcohol percentage of any purely fermented beverage (at 25%, it's higher than any wine out there). I had a sample of it at a beer festival a few years ago, and it was fantastic.

I think that Sam Calagione (from Dogfish Head Brewery) also has a few "extreme brews" that are in the low 20% range as well.

From the New Scientist Tech. Note that they do not provide figures, but they do mention the potential changes in flavor. Also, since the Feds currently limit the maximum ABV to 25% before requiring a Distillers license, having a "Super" yeast that can go to 40%+ is kind of a moot point

Genetically modified yeast could boost biofuels
19:00 07 December 2006
NewScientist.com news service
Tom Simonite

A novel genetic engineering technique has been used to make yeast more resistant to the ill-effects of alcohol. It could dramatically boost the efficiency of generating ethanol-based fuels from corn and plant waste.

Yeast produces alcohol as a by-product of its own metabolism, which can then be used as a replacement for petroleum. But yeast is also poisoned by this alcohol. As well as limiting the amount of alcohol in drinks made without distillation, this limitation restricts the efficiency of biofuel production, which converts corn or plant waste into ethanol.

"The fact is that science had run out of methods to increase alcohol tolerance," says Greg Stephanopoulos, a chemical engineer at MIT in the US. Conventional genetic modification techniques involve altering one gene at a time, and have been ineffective because alcohol tolerance is the product of many genes working together, he explains.

Stephanopoulos and colleagues at MIT and the Whitehead Institute for Biomedical Research, also in Massachusetts, US, solved this by altering a gene that controls the activity of many others.

Alcohol tolerance
The researchers referred to a known sequence of the yeast genome in order to create a mutant version of a gene called SPT15. "This encodes a protein that controls the activity of a lot of other metabolism genes," explains Stephanopoulos. The technique has been used before on bacteria, but never on such a complicated organism as yeast.

The modified yeast cells were found to have a significantly higher alcohol tolerance than normal yeast. The researchers do not yet know why this is, but they also found that it also produced 50% more ethanol during a 21-hour period.

Fiddling with so many genes at once would normally "break the cell", Stephanopoulos says. However, his modified yeast was created with a mixture of mutant and normal genes. "We kept a copy of the [normal] gene to buffer against that," he says.

Industrial strains
The technique has so far only been tested on laboratory strains of yeast, but Stephanopoulos believes it should work just as well on the industrial strains used to make biofuel from corn and plant waste.

Currently, when fermenting corn, these industrial strains are killed when alcohol level reach 12% to 15%. The modified yeast could perhaps survive in several times this concentration. "Being able to increase that even a few-fold would make producing biofuel much more economic," Stephanopoulos says. More alcohol could be produced before having to siphon it off to allow fermentation to continue.

Stephanopoulos adds that genetic engineering could perhaps make yeast that can process toxic compounds that make other types of plant waste unsuitable for ethanol production.

Using the technique on yeast used to brew beer or wine might be interesting too, Stephanopoulos acknowledges. "It could produce new kinds of drinks with different alcohol content," he told New Scientist, "but it would also affect the other compounds produced during fermentation so the taste might not be so good."

Good find Angus!!! If these Yeasts were Encapsulated like some of the Lallemand yeasts and packed in a continuous flow fermentation system this would kick ass for making bio-fuels more cost effective.

Cheers,
Wrathwilde

Angus said:

Currently, when fermenting corn, these industrial strains are killed when alcohol level reach 12% to 15%. The modified yeast could perhaps survive in several times this concentration. "Being able to increase that even a few-fold would make producing biofuel much more economic," Stephanopoulos says. More alcohol could be produced before having to siphon it off to allow fermentation to continue.

Click to expand...

http://www.northernbrewer.com/pics/fullsize/distillers_yeast.jpg



Northern Brewer has:http://pivo.northernbrewer.com/nbstore/action/search-do?searchTerm=distillers+yeast&offset=20
Superstart Distiller's Yeast
This distiller's yeast requires additional nutrients to ferment up to 22% alcohol. Comes in a 1 lb. bulk pack.
This is the highest percentage alcohol I have seen so far.

The other thing you need to read is the fine print in the instructions for the strain (not on the bag) where they note that you need to maintain a fermentation temp of 90F to achieve that ethanol production. I imagine with all the fusels produced at that high a temperature, you wouldn't want to drink the result without fractional distillation to remove the higher order alcohols.

This conversation pops up every so often here on Got Mead. Frankly I don't know what the fascination is with fusel ridden, hot, overly alcoholic meads for the sake of saying "Yeah, I made a 25% ABV, it was hot and never did mellow out, but it was 25%!!" Color me a killjoy but whoop-de-f#!*&@g-do. Seems to be a pretty simple thing to distill if you want higher proof.

Based on my experience and a couple of other folks I know, the distillation yeast is not well-suited for mead production unless you're going to distill it. As Wayne mentions below, HIGH TEMPERATURE FERMENTATION REQUIRED, you know what that does to mead and why it's not desirable.

I say this over and over, but it never seems to land. Start with the basics. Making a good traditional mead consistently is more of a challenge to meadmakers in my opinion than any mango-celery-horseradish-appleskin-chai-salmonberry-seaweed-soysauce weirdomel can ever be. When you give someone a glass of your traditional it speaks volumes about your ability/inability to make mead. Making a bunch of exotic combinations is fun, but will hide recipe faults, production faults and aging faults. Learn to play the instrument before you try a 20 minute solo.

Cheers,

Oskaar

My opinion on why these "super" yeasts are used by distillers in the first place.

It is not necessary to create a 22% ABV liquor before distilling it. Distillation is the extraction of the alcohol, using either heat or cold methods, and can be performed on a 5% ABV beer if needed. This may mean that a lot more of the original liquor will be needed to obtain a sufficient amount of distillate, so having something with a higher ABV may make things quicker in the long run, but not necessary.

The important item for any distillary to worry about is the cost of production. The fermentable sugar is the central piece of this cost. It is therefore vital for any distiller to ensure he ferments all of the sugar, i.e. complete attenuation, since any unfermented sugar will be wasted when the liquor is distilled. Therefore, I assume the distiller will create a mash that has an ABV of around 15-20%, and will then use this "super" yeast to blast through the sugar. It is also important to note that any fusels that these yeast create during fermentation will be extracted and discarded as part of the distillation.

Therefore, I would stay away from even considering them for use in Mead. Not only do you run into the problems associated with stalling etc., but the yeast were selected for power rather than flavor/color retention etc. and may result in excess fusels. Stick with the proven yeast listed in the table, and if you want to create a monster Mead above 18% ABV, experiment with step feeding and nutrient dose to see what you get. Or follow Oskaarz advice by aiming to perfect the 14% Show Mead instead.

Angus

There is a very good reason for developing and using super yeasts, especially when making fuel alcohol. It helps to cut energy costs during the distillation. When you distill you have to heat the entire amount of liquid to near boiling. A 20% ABV beer has half the volume as a 10% ABV beer for the same amount of alcohol. This makes a big difference in the amount of energy needed for distillation. If they can make a yeast that works at 40% they can further cut the distillation costs.

However I would never consider using any of these yeasts for something I was going to drink without distillation. The hot alcohols and other off flavors would be horrible. A 10 to 15% mead is plenty strong enough to get drunk on if that is your goal. My goal for mead is to have a beverage I really enjoy.
If you really must have a stronger mead Lalvin EC1118 and Red Star Premier Cuvee are good to about 18%. But that is going to take a long time to age before it is drinkable.

Craig