Brewing with Ergosterol and Safflower Oil

[coryforsenate]

I've got some ergosterol and high oleic safflower oil. I'll be making a few brews with them with no aeration, record the OG/FG, sensory evaluation, concentrations of both compounds, etc. I chose high oleic safflower oil because it's lower in saturated fat than olive oil.

For those who wondered why olive oil has been used in the past: Saccharomyces cerevisiae has one desaturase, Ole1p, which puts a double bond at Δ9. This requires oxygen. Oleic acid happens to be an Δ9 fatty acid.

Stay tuned for more to come.

 

[TopherM21]

I'm not a chemist, so I understand very little of that middle paragraph...

But are you worried about head retention? As I understand, fats/oils kill a good head.

 

[lamarguy]

I'm interested to see your results.

The New Belgium experiment showed (1) slight differences in the taste panel, (2) longer fermentation time, and (3) slight decrease in cell health.

Yeast are highly adaptable but you are asking them to modify their preferred growth process.

 

[coryforsenate]

@ TopherM21, The amount of oil added is very small.

@ lamarguy, The New Belgium experiment didn't use ergosterol. Based on reading research journals involving ergosterol supplementation, I'm guessing that was the "missing link". There's no making ergosterol without oxygen and no ergosterol is going to impact the cell membrane.

 

[coryforsenate]

:update:

So I made a 1L starter with 4oz malt extract and added ergosterol to 10ppm. Did the usual shake the flask and then let it sit for 4 days. Started cold crashing last night and I can say that qualitatively that there are a lot more yeast than usual.

Will be brewing a dubbel later this week.

 

[broadbill]

:update:

So I made a 1L starter with 4oz malt extract and added ergosterol to 10ppm. Did the usual shake the flask and then let it sit for 4 days. Started cold crashing last night and I can say that qualitatively that there are a lot more yeast than usual.

Will be brewing a dubbel later this week.

I don't suppose you prepared an untreated control (no ergosterol) alongside your treated starter to compare it to?

Leaving the issue of qualitative analysis aside, if you don't have an untreated control to compare to, you can't make any firm conclusions as to if ergosterol had any effect on yeast growth. For example, you might have added more yeast into this starter than you did for previous starters and that is why you have more yeast in your starter after 4 days.

 

[coryforsenate]

@broadbill

It is possible that Wyeast sent me triple the normal amount of yeast in the smack pack.

I may do two little starters later this week with bread yeast and compare with and without.

 

[broadbill]

@broadbill

It is possible that Wyeast sent me triple the normal amount of yeast in the smack pack.

If they sent you an extra 10 yeast cells, it could have a big effect, due to exponential growth over a four day period.

I may do two little starters later this week with bread yeast and compare with and without.

Keep in mind that Grady Hull's thesis compared Olive Oil addition to wort that was oxygenated through a stone and NOT a negative control (no treatment whatsoever). It was a weird way to do the experiment (i.e. no difference meant there was really a positive effect of the olive oil as it was similar to what we already see with oxygenation), it was a messy study and make interpretation difficult.

 

[coryforsenate]

@broadbill

10 extra yeast cells in the original solution wouldn't make a visible difference after 4 days given the billions of yeast cells already present. It would take considerably more time, and that's assuming every single variable was perfectly constant, including mutation rates.

And I'm well aware of how Hull's thesis was performed.

 

[lamarguy]

 

[chrisdb]

where did you get ergosterol?

 

[lamarguy]

Safety data for ergosterol

Very toxic if swallowed. May be harmful if inhaled or absorbed through the skin.

 

[coryforsenate]

@chrisdb

From Sigma, http://www.sigmaaldrich.com/catalog...0|SIGMA&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPEC.

@lamarguy

The toxicity comes from the potential for hypercalcemia. Ergosterol is a precursor for vitamin D. Sunlight turns it into viosterol, which is immediately before vitamin D2.

 

[broadbill]

@broadbill

10 extra yeast cells in the original solution wouldn't make a visible difference after 4 days given the billions of yeast cells already present. It would take considerably more time, and that's assuming every single variable was perfectly constant, including mutation rates.

4 days of yeast starter growth = 96hours. Assuming a 2h doubling time, you would have 48 doublings in a 96h period. 10 cells doubling 48 times would give you an extra 10 x 2^48 = 2.8x10^15 extra cells.

Of course this number is a way overestimate for a number of reasons (nutrient restriction, lag and stationary phases of yeast growth, etc). My point was that small differences in yeast number can lead to big changes in yeast number after 4 days. Any experiment that goes on for that long, with organisms that divide that quickly, consistent starting concentrations are crucial.

You are probably correct that you wouldn't not be able to see a difference qualitatively in this situation. However, If this is your argument than you shouldn't be able to see a difference with ergosterol supplementation either.

And I'm well aware of how Hull's thesis was performed.

Then you probably know there were some major experimental flaws in that work, right? The reason I bring this up is that you think you might have found the "missing link" in their research, but I'm not convinced their work to that strong to start with.