High alcohol production?

[blaskos]

Im writing a paper on ethanol tolerance of yeast and was wondering if anyone had some good sites or papers that they could refer me to. Also if you know of anything why chemically or molecularly why yeast cant survive. I believe its due to the pH levels... but is that it?

[tylerpeters]

It is not the pH directly that the yeast have a problem with, it is the fact that they are surrounded by a toxin (EtOH). yeast have alcohol ratings in which they cannot survive, at least in any great number, above. What happens is the nutrients are depleted in the solution and the excretion, which again is EtOH, builds up creating an environment that is very toxic for them. Yeast cannot use the EtOH as a terminal electron acceptor nor a source of energy because of their metabolic properties. As you may have found, EtOH is a by-product of fermentation. And as you may know fermentation provides cells the ability to survive, without oxygen in this case, but is horribly energy expensive. Simply put, the yeast must consume at a high rate to drive fermentation. As the nutrients are consumed in the medium or what you may call green-beer at this point in production, the wastes accumulate. If you could imagine living in one room and having to eat what was there and excrete there too (not a nice visual) you would probably experience first hand what the yeast do in fermentation. Your tolerance to that 'room scenario' would your measured ability to withstand your excrements, which is exactly what the alcohol rating on yeast is. Remember that wine yeast have a higher tolerance and therefor can produce more alcohol. Wine also carries with it a higher sugar content (in most cases) to drive this fermentation. Hopefully you find some of that useful.

If you really want to get a lot of information - contact Wyeast labs or White labs who are the major wine and beer yeast producers in the world.

[blaskos]

Yeah that helped a lot. I already emailed wyeast labs and we will see if they respond. Do you possibly know of a yeast alcohol ratings chart? Thanks again for the information. My paper is about Genetically engineering yeast (somehow) to increase their tolerance to ethanol.

Also, a side note. Has anyone ever tried to use wine yeast to make beer to increase the etOH content. I dunno if this is possible but just wondering if it woudl be somewhat tasty!

It is not the pH directly that the yeast have a problem with, it is the fact that they are surrounded by a toxin (EtOH). yeast have alcohol ratings in which they cannot survive, at least in any great number, above. What happens is the nutrients are depleted in the solution and the excretion, which again is EtOH, builds up creating an environment that is very toxic for them. Yeast cannot use the EtOH as a terminal electron acceptor nor a source of energy because of their metabolic properties. As you may have found, EtOH is a by-product of fermentation. And as you may know fermentation provides cells the ability to survive, without oxygen in this case, but is horribly energy expensive. Simply put, the yeast must consume at a high rate to drive fermentation. As the nutrients are consumed in the medium or what you may call green-beer at this point in production, the wastes accumulate. If you could imagine living in one room and having to eat what was there and excrete there too (not a nice visual) you would probably experience first hand what the yeast do in fermentation. Your tolerance to that 'room scenario' would your measured ability to withstand your excrements, which is exactly what the alcohol rating on yeast is. Remember that wine yeast have a higher tolerance and therefor can produce more alcohol. Wine also carries with it a higher sugar content (in most cases) to drive this fermentation. Hopefully you find some of that useful.

If you really want to get a lot of information - contact Wyeast labs or White labs who are the major wine and beer yeast producers in the world.

[tylerpeters]

I dont personally have a chart, but I'm sure one exists somewhere. as far as using wine yeast in beer - you really dont need to do that and you probably wouldnt want to. In ultra high gravity beers you can simply use an enzyme to breakdown all starchs to their simpliest unit and 'over-pitch' yeast to achieve a higher alcohol. you also could just simply over-pitch which is using a greater proportion of yeast than you normally would. some breweries over-pitch their wort with yeast and every so often hit the fermenting beer with more wort to increase the amount of available nutrients in the early stages of fermentation to really drive the fermentation.

you would want to avoid using a wine strain in a beer because remember that it is not only CO2 and EtOH coming out of the yeast. the reason you have so many different types of yeast is because they not only have such a vast fermantation profile differences, but they also can contribute phenolic compounds that influence the flavor of the beer. For example... take the weihenstephan strain for wheat beers. This particular yeast gives a mild banana flavor to the beer. This is due to fermenting at higher temperatures (because this is an ale yeast as opposed to a lager yeast) which allows the fermentation to run slightly faster than that of the colder lager strain optimum temperature fermentation and due to that particular strain of yeast. Many different strains exist that produce phenolic compounds which you probably understand from organic chemistry as esters.

when you write your paper, really think about why you would really want genetically modified yeast. the strains we have now are more than sufficient when used correctly. as a biologist and a student of the university with the most controversy in the nation over genetic engineering, i take both sides of this argument. I support the research, but I would never use the modified yeast because it simply is not practical at this point. why use a new strain when a 1000 year old strain has worked just fine? think about these points when you write your paper.

[gitchegumee]

Strains of yeast with high EtOH tolerance are being developed, genetically or not, for production of EtOH fuels among other things. Also, there are strains that can produce above 20% used in the distilling industry. Distillation doesn't require such balanced nuances that beer production does. Might be best to contact an EtOH fuel producer or equipment supplier/contractor/consultant. And I believe that Sam Adams uses a wine (champagne?) yeast for their "triple bock". Good luck!

[blaskos]

The only advantage (as of now) that i can think of is using this yeast for making ethanol to power cars.... higher return when they ferment the corn. Anyways yea i need to think of both sides of the argument as well and need to say why GE yeast is not a good idea.

I dont personally have a chart, but I'm sure one exists somewhere. as far as using wine yeast in beer - you really dont need to do that and you probably wouldnt want to. In ultra high gravity beers you can simply use an enzyme to breakdown all starchs to their simpliest unit and 'over-pitch' yeast to achieve a higher alcohol. you also could just simply over-pitch which is using a greater proportion of yeast than you normally would. some breweries over-pitch their wort with yeast and every so often hit the fermenting beer with more wort to increase the amount of available nutrients in the early stages of fermentation to really drive the fermentation.

you would want to avoid using a wine strain in a beer because remember that it is not only CO2 and EtOH coming out of the yeast. the reason you have so many different types of yeast is because they not only have such a vast fermantation profile differences, but they also can contribute phenolic compounds that influence the flavor of the beer. For example... take the weihenstephan strain for wheat beers. This particular yeast gives a mild banana flavor to the beer. This is due to fermenting at higher temperatures (because this is an ale yeast as opposed to a lager yeast) which allows the fermentation to run slightly faster than that of the colder lager strain optimum temperature fermentation and due to that particular strain of yeast. Many different strains exist that produce phenolic compounds which you probably understand from organic chemistry as esters.

when you write your paper, really think about why you would really want genetically modified yeast. the strains we have now are more than sufficient when used correctly. as a biologist and a student of the university with the most controversy in the nation over genetic engineering, i take both sides of this argument. I support the research, but I would never use the modified yeast because it simply is not practical at this point. why use a new strain when a 1000 year old strain has worked just fine? think about these points when you write your paper.

[dick murton]

What level of alcohol are you talking about. One of the normal ale yeast strains I use to brew with allowed me to produce a 17% ABV beer, and if I hadn't stopped the aeration quite so early, would have allowed us to hit 18 or 19% - but as this was a one off, for "in house" consumption only, (a commisseration brew when we closed a brewery) I didn't have a chance to repeat it. This same yeast was regularly used to produce 11% barley wine.

I heard, but never had it confirmed, that the company pilot brewery had produced a drinkable (??) 24% beer using a genetically modified yeast.

Have to agree with previous statements about not wanting to / needing to use modified yeasts for beverage production - unless you want to go for pure alcohol production and add flavourings etc to produce "beer" - see Charlie Bamforth's recent article in the Brewer's Guardian for a nightmare vision.

Cheers

[blaskos]

Well im not saying that we should use GE yeast, but im just exploring the possability of it happening in the future.

So far the research i have now is quite interesting. Yeast behave differently to ethanol they make and ethanol introduced. There are more stuff... as i finish my paper i will post it and see what you guys think.

What level of alcohol are you talking about. One of the normal ale yeast strains I use to brew with allowed me to produce a 17% ABV beer, and if I hadn't stopped the aeration quite so early, would have allowed us to hit 18 or 19% - but as this was a one off, for "in house" consumption only, (a commisseration brew when we closed a brewery) I didn't have a chance to repeat it. This same yeast was regularly used to produce 11% barley wine.

I heard, but never had it confirmed, that the company pilot brewery had produced a drinkable (??) 24% beer using a genetically modified yeast.

Have to agree with previous statements about not wanting to / needing to use modified yeasts for beverage production - unless you want to go for pure alcohol production and add flavourings etc to produce "beer" - see Charlie Bamforth's recent article in the Brewer's Guardian for a nightmare vision.

Cheers

[GarySped]

High Ethanol tolerant yeast

Your best source for information is Prof. Mike Ingledew at the University of Saskatechewan. He and his team showed all the parameters necessary to get yeast to produce upto 23% by volume alcohol (yes you read that right 23%) without any prior training of the yeast strain. The factors include right nutrition (as others mention here) and removal of metabolites such as acetic and lactic acids. The company Alltech, Inc in KY produced a very nice laminated sheet showing all the factors involved, based on Ingledew's work.
In addition, all the major breweries (the Big Three) have hired microbiologists trained by Ingledew. Contact Ingledew (now part time retired) at Univ. Sask in Canada or check the literature for any paper from his lab. You won't need to go any further to get the goods on this topic.

Gary.