Oleic acid and ergosterol in fermentation

[ipscman]

Periodically we underoxygenate our pitched yeast/wort. I came across two statements that seem like a great answer to this problem when the fermentation is stalling. Any thoughts, experience with this?

1. Brewing, 1999 (Ian Ornsey) "If an early fermentation becomes oxygen-starved for some reason, it is possible to reverse this deficiency by additional ergosterol (one of the three major yeast membrane sterols) in low concentration (5 mg 1-1). Oleic acid can also be used to reverse the situation, which most commonly arises during high-gravity brewing." p. 117

2. Handbook of Brewing, 2008 (Priest) "When ergosterol and an unsaturated fatty acid, such as oleic acid, are added to the wort, the requirement for oxygen disappears." p. 299

I don't understand the 5mg 1-1 number. I do understand that this approach is used by pro breweries and may be accessible for home brewers if we can access oleic acid and/or ergosterol.

????

 

[GilaMinumBeer]

I know linoleic acid has been tried as a sub for the oleic with positive blind taste panels but, little solid long term evidence of the study. IIUC, the ergosterol is a hard summabitch to come by lest you purchase for a lab.

I dunno what the "1-1" reference is. I'd guess it describes a solution but am not certain.

 

[Clayton]

When ergosterol and an unsaturated fatty acid, such as oleic acid, are added to the wort, the requirement for oxygen disappears."

i have heard this before, when makeing liquid cultures of mushroom mycelia
the additon of a unsaturated fatty acid removed the need for gas exchange (oxygen) in the vessel
they where using a needle dipped in olive oil as a dose for a 1/2 quart LC

 

[menschmaschine]

This comes back to unsaturated fatty acids and the whole olive oil thing. Olive oil contains oleic acid (mono-unsaturated). Brewers have tried this with good results, but the amount of olive oil to add is miniscule and typically added to the yeast starter or storage vessel, not the whole batch of wort. This is only effective in early fermentation when the yeast are multiplying and building up their cell walls. Later in fermentation, they no longer do this (for all intents and purposes), so it wouldn't be useful for, say, a 1.020 stuck fermentation.

Good topic though.

 

[ipscman]

I posted the same question to Wyeast and got this response:

"I don’t understand the 1-1 part either. I assume 5mg is the important part. You can get these UFAs, but instead, you can use olive oil which you should have easy access to. About 1.5mg – 3.0mg per 5 gal batch."

This is interesting. Just add olive oil to a fermentation that is becomes oxygen-starved for some reason?

Any experience with this? Opps. I posted this without refreshing the topic. Have to digest what you all are saying.

 

[ipscman]

This comes back to unsaturated fatty acids and the whole olive oil thing. Olive oil contains oleic acid (mono-unsaturated). Brewers have tried this with good results, but the amount of olive oil to add is miniscule and typically added to the yeast starter or storage vessel, not the whole batch of wort. This is only effective in early fermentation when the yeast are multiplying and building up their cell walls. Later in fermentation, they no longer do this (for all intents and purposes), so it wouldn't be useful for, say, a 1.020 stuck fermentation.

Good topic though.

I'm beyond my pay grade for sure but both of these resources seem to be talking about additions to the wort, not the yeast starter:

1. Brewing, 1999 (Ian Ornsey) "If an early fermentation becomes oxygen-starved for some reason, it is possible tro reverse this deficiency by additional ergosterol (one of the three major yeast membrane sterols) in low concentration (5 mg 1-1). Oleic acid can also be used to reverse the situation, which most commonly arises during high-gravity brewing." p. 117

2. Handbook of Brewing, 2008 (Priest) "When ergosterol and an unsaturated fatty acid, such as oleic acid, are added to the wort, the requirement for oxygen disappears." p. 299

The first book is written by a brewery owner in England. Second is a relatively commonly used text.

???

 

[menschmaschine]

I'm beyond my pay grade for sure but both of these resources seem to be talking about additions to the wort, not the yeast startet:

1. Brewing, 1999 (Ian Ornsey) "If an early fermentation becomes oxygen-starved for some reason, it is possible tro reverse this deficiency by additional ergosterol (one of the three major yeast membrane sterols) in low concentration (5 mg 1-1). Oleic acid can also be used to reverse the situation, which most commonly arises during high-gravity brewing." p. 117

2. Handbook of Brewing, 2008 (Priest) "When ergosterol and an unsaturated fatty acid, such as oleic acid, are added to the wort, the requirement for oxygen disappears." p. 299

The first book is written by a brewery owner in England. Second is a relatively commonly used text.

???

Either way (added to wort or yeast solution/starter) you're giving the yeast the required UFAs. But most of the experiments done with olive oil have been done so the olive oil was added to the yeast pre-pitching. So, regarding No. 2, the point is to get it to the yeast, so it would seemingly be more prudent, if anticipating a low wort oxygenation, to add it to the yeast prior to pitching so that they are ready to go. Adding the same amount of UFAs to a whole batch of wort prior to the start of fermentation might not be as efficient for the yeast to access it than if it was added to a small volume of starter or yeast solution.

For reference No. 1, that is probably for breweries who can measure dissolved oxygen in wort and, if finding a deficiency early in fermentation (knowing it might affect their strict quality control), have an alternative by adding oleic acid. Unless the homebrewer has a DO meter, I don't see how we could effectively make use of this method once we pitch the yeast. Of course, it is something to consider... to add olive oil to the starter for a high-gravity brew to help the yeast meet their requirements for a healthy cell-membrane.

 

[pjj2ba]

I don't understand the 5mg 1-1 number. I do understand that this approach is used by pro breweries and may be accessible for home brewers if we can access oleic acid and/or ergosterol.

It is not 5mg 1-1, but 5 mg l-1, that's L not 1. Some journals don't like to use the "/" characther. So to decipher it is 5 mg/liter, l-1 is the same as /l

 

[ipscman]

Either way (added to wort or yeast solution/starter) you're giving the yeast the required UFAs. But most of the experiments done with olive oil have been done so the olive oil was added to the yeast pre-pitching. So, regarding No. 2, the point is to get it to the yeast, so it would seemingly be more prudent, if anticipating a low wort oxygenation, to add it to the yeast prior to pitching so that they are ready to go. Adding the same amount of UFAs to a whole batch of wort prior to the start of fermentation might not be as efficient for the yeast to access it than if it was added to a small volume of starter or yeast solution.

For reference No. 1, that is probably for breweries who can measure dissolved oxygen in wort and, if finding a deficiency early in fermentation (knowing it might affect their strict quality control), have an alternative by adding oleic acid. Unless the homebrewer has a DO meter, I don't see how we could effectively make use of this method once we pitch the yeast. Of course, it is something to consider... to add olive oil to the starter for a high-gravity brew to help the yeast meet their requirements for a healthy cell-membrane.

Thanks. Your points are well made and taken.

I will plan to add some olive oil to yeast start-ups when preparing for a high gravity brew. I'm not sure if it makes sense to add the same amount as you would for the brew, as suggested by my Wyeast friend, or a smaller amount. Any thoughts?

 

[menschmaschine]

I'm not sure if it makes sense to add the same amount as you would for the brew, as suggested by my Wyeast friend, or a smaller amount. Any thoughts?

I don't recall the exact amounts, but a study was done on this and published in Brew Your Own magazine. IIRC, it's difficult for the homebrewer to accurately measure the miniscule volume of olive oil needed. So it was essentially a tiny droplet, like from a pin head. You definitely don't want to overdo it.

 

[ipscman]

Here's the link to a thesis on this very subject, the results and impact on esters, oxidation, taste, attenuation, etc.

http://www.brewcrazy.com/hull-olive-oil-thesis.pdf

 

[TheChemist]

This article (Tracy Aquilla. "The Biochemistry of Yeast." BrewingTechniques vol. 5, no. 2, March/April 1997) and Vol2 of Malting and Brewing Science by hough, Briggs, Stevens, and Young cite the possibility of cold trub actually producing the fatty esters and lipids that could aid sterol production. So....leaving your cold break in the fermenter could work instead of adding oil?

 

[menschmaschine]

This article (Tracy Aquilla. "The Biochemistry of Yeast." BrewingTechniques vol. 5, no. 2, March/April 1997) and Vol2 of Malting and Brewing Science by hough, Briggs, Stevens, and Young cite the possibility of cold trub actually producing the fatty esters and lipids that could aid sterol production. So....leaving your cold break in the fermenter could work instead of adding oil?

That may be. Lipids are both good and bad in beer. (See this thread.) I understand that it may be beneficial to have a small amount of break material in the fermenter. Too much is bad too.