Higher alcohol

[Dannken]

HI to everyone, I want to know how can I avoid higher alcohols in my beers, I only brew all malt beers, and cant find out an explanation for this, hope for ur help.

[RobZamites]

Lower fermentation temperatures would be a good start - for ales, no higher than, oh, 68F. Just my two cents.

Rob

[Dannken]

Higher alcohols

Yes mister, im brewing ales

[Alex T]

hi,

i would also try and control the temp of fermentation to 22degC max.

alex

[Fred Scheer]

Higher alcohols

There are several ways of which this "fusel alcohols" are formed:
YEAST converts amino acids to higher alcohols
TEMPERATURE (already mentioned in the two previous posts)
SUGARS are synthesized by way of acetate.

Almost 85% of the higher alcohols are formed during the primary fermentation, and can not be removed in later stages..

So, now that we told you (somehow...:-) how they are formed, what can you do to eliminate them:

* increase your yeast pitching rate. Normal it should be 1MIO/ml; I would start with 1.5MIO/ml and see if it helps.
* cool your wort to about 65*F and ferment at this temperature
* after your primary fermentation is 1* Plato above your end fermentation degree, seal the tank.
* check your lines so that no oxygen is indroduced after wort cooler
* check with your malt supplier so that you have enough amino acid. protein etc.

If you need more help, do not hesitate to contact me.

Fred Scheer

[Ziggy-san]

I've read (in very loose discussions) that certain higher alcohols can be metabolized into esters by yeast if the beer is allowed to rest for a period of time after primary fermentation is complete.

Do any of you have any direct experience with this or and references that youd care to share that discuss this activity?

[mlhardesty]

fred,
was that pitching rate 1 million cells / ml or 1 million cells / degree P / ml?

[Michael Murphy]

thats a real general question, if you want to produce a beer with the flavor without all the alc. make sure the wort is highly dextrinous, by mashing at a higher temp is a start.
Interupting fermentation, by cooling it is also another way, but if you dont filter out the yeast or pasterize you may have more fermenting going on a later times causing more problems. Especially if you have high O2 pick up.


Rule of thumb...Less malt more water

[Fred Scheer]

higher alcohol

Thanks, I should have be more detailed about this.

I recommend 1.5 million yeast cells/ degree Plato

Thanks for reminding me

[Nicolas]

Now my two cents.

Higher alyohols are produced by certain yeast stains in different concentrations. These higher alcohols arise from different amino acdis. (Valine, Iso-Leucin, Leucin). And from Diacetyl --> 2,3 Butandiol. Top fermenting yeast strains (due to the higher fermentation temp. and NOT because they are top fermenting) also produce higher alcohols. To aviod higher alcohols you should keep your temp relatively low, as already stated. What also keeps a low concentrations of higher alcohols is pressure fermentation (pressure less for approx. one or two days and then with a slight CO2 counter pressure).
What was also stated is that these higher alcohols might react to esters. This is not quite true. Generally an Ester is a product of the reaction between alcohols and carbon acids. But this reaction does not take place during fermantation (since the reation energy needed for this reaction is way too high). The main part of the esters found in beer arise from a reaction with "activated" fatty acids and Ethanol. Or the other way around from "activated Ethanol" (Acetyl CO-A) and fatty acids. This is due to the fact that you have a high concentration of Ethanol in the young beer. Esters arising from higher alcohls are not in a so high conecntration in final beer. This is due to the fact that your concentration of higheralcohols is not so high as Ethanol/ Acetyl CO-A.

Hope that helped a little bit.

Cheers nic