Interesting scholarly article

[B8A_AMYLASE]

For anyone interested in some research on the physiological stresses and reactions to yeast in a high gravity beer check our this link I have attached ( it should be readable) I recently composed a paper and this was one of my references and I thought it was very interesting... So what if I like to read Journals and dissertations!

View attachment high gravity beer and yeast.pdf

 

[WoodlandBrew]

That's an interesting read, but I'm not sure that it would represent results from an all barley high gravity wort most homebrewers would prepare. Do you think this could be Nitrogen limitation?

A 12°P wort requires 150mg of FAN per Liter which is 12.5mg per liter degree Plato.[1] It looks like there is a typo on Table 1 of the paper you linked. There is no way there is more FAN than Maltose unless it is supplemented, which is not shown in the Materials and Methods. FAN is normally measured as mg per liter, so it's probably safe to assume that's what they meant. It looks like the supplements did not contain a nitrogen source which would make this study not map well to a high gravity all barley wort. The FAN concentrations are very low compared to what is typical for beer.

FAN L-1 °P-1 should be about 12.5mg. Note that only the un-supplemented wort has more than 12.5mg L-1 °-1

°P    FAN(mg) L-1   FAN(mg)  L-1 °P-1
14    240           17.1
21    210           10.0
21    220           10.5
24    192           8.0
24    201           8.4

The growth rate of s. cerevisiae is about 1/8 of the rate under nitrogen starvation, and the biomass yield is about half.[2] This would explain the results that were shown with this study.

[1] O'Conner-Cox, E. S. C., and W. M. Ingledew. 1989. Wort nitrogenous sources. Their use by brewing yeasts: a review. J. Am. Soc. Brew. Chem. 47:102-108.

[2] Schulze, Ulrik, et al. "Physiological effects of nitrogen starvation in an anaerobic batch culture of Saccharomyces cerevisiae." Microbiology 142.8 (1996): 2299-2310.

 

[Talgrath]

I'm not quite sure I followed along entirely, but the abstract is stating they had better success with malt syrup (liquid malt extract?) instead of glucose syrup, which seems interesting given I had often heard straight sugar was best for goosing up alcohol content.

 

[WoodlandBrew]

malt syrup (liquid malt extract?)

It's actually high maltose corn syrup. There is almost no FAN in it. Very different than malt extract.

 

[Talgrath]

Okay, so corn syrup that is high in maltose instead of fructose? Does this mean anything for folks try to goose the gravity of homebrew barleywine then?

 

[B8A_AMYLASE]

Sorry Im 12 hours ahead so my responses might be a little delayed but very good point, I did not cite this particular source but thought it would do well here. I will see if I can find anything

 

[suregork]

Brian Gibson has authored two fantastic reviews on the subject (both free to read as well!):
http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.2011.tb00472.x/abstract
http://femsre.oxfordjournals.org/content/31/5/535.long

The first one (i.e. the 125th Anniversary Review) is more relevant to homebrewers.

JIB's 125th Anniversary Review series is a great source for scientific information on anything brewing related:
http://onlinelibrary.wiley.com/jour...e/125th_anniversary_reviews_virtual_issue.htm

There are reviews on bacteria, hops, diacetyl, flocculation, etc. And all free to read!