At a whisky distillery...

[Externet]

Took a tour at a nearby distillery and they were fermenting the mash on huge tanks with no lid and at 66 degrees Farenheit.

 

It seemed unusual to me, without much knowledge of producing ethanol. Does 'no lid' and '66 F' seem normal to you ? Or it all depends on the yeast type, and is there a yeast that 'works' at that temperature ?

[Sensei]

(I am not making whisky, yet)

 

I am adding yeast when solution of sugar and water decreased to 35 C temperature.

While fermentation they are kept close to heater/radiator (there is flowing through it hot water to heat house).

The whole mash is kept at up to 35 C temperature during fermentation.

 

Too large temperature will kill yeast,

too low temperature will decelerate/stop fermentation.

Sometimes long time fermentation is preferred.

 

One of the nicest ethanol received was from 72h turbo yeast. After 72h there was 14%+ of ethanol.

It goes so fast, that CO₂ bubbles are every second or two, from 20L tank (filled to 16L).

I could imagine that large container would produce plentiful more CO₂, depending on yeast type.

Mixed corn/grain could make enough layer to keep below layers from Oxygen from air.

 

One way to stop fermentation is to heat it, to kill yeast.

After that there are added compounds which will react with dead yeast remains.

And they will gather on the bottom of tank.

It could take couple days, after that there is needed filtering.

While making many wines there is needed couple times such stage. Clarifying wine.

 

ps. You should search for "how to make whisky" tutorials on the net.. and see whether temperature is right..

And even better will be your own experience in making it.

Edited December 12, 2016 by Sensei

[Externet]

Thanks.

Found a yeasts temperature chart but for beer, and are 'low' temperature; will look for whiskys.

----> https://byo.com/resources/yeast

 

Many 30K gallon tanks I saw

----> https://www.whisky.com/fileadmin/_processed_/csm_fermenter_a644353ce0_66e53aac0234e0936fadba56951c07c1_1eeaef6067.jpg

[Sensei]

Beer, wine, vodka, whisky is all different story..

 

They mention here 20 C.

https://www.whisky.com/information/knowledge/production/details/fermentation.html

"As yeast can’t stand hot temperatures the wort is cooled down to about 20°C before it is married with the yeast in washbacks."

 

If I tried to use temperature below 35 C, at the beginning, I had to restart everything with new yeast..

On each yeast package there is mentioned procedure which should be followed.

Edited December 12, 2016 by Sensei

[StringJunky]

The lower the temperature you ferment at the less volatiles are lost during fermentation which contribute to the bouquet and more subtle tastes. They'll be using a strain of yeast that works ok at that temperature.

 

Carbon dioxide is heavier than air so it tends sit as a blanket over the mash cutting off the air. I bet the sides are quite deep from the surface of the liquid to the top of the tank.

 

 

The preservation of wine aroma and flavor due to lower fermentation temperatures has been well documented by research. Molina et al. (2007) found that higher concentrations of esters are developed at lower temperature fermentations due to a reduction of evaporative (volatile) loss, which increases stability of flavor and aroma compounds in wine.....

 

....Cooler fermentations have been shown to improve the clarity of wine (Comfort 2012). Clarity is typically achieved through racking, cold settling, cold stabilization, and fining, but low temperature fermentation may be an alternative option for enhanced clarity. At lower temperatures, yeast cells are less likely to give off colloids, thus improving clearness (Jackson 2014). Colloids derive from yeast and pectin, which form polysaccharides and aggregates after a physiochemical change (i.e. temperature), diminishing clarity (Drioli et al. 2010). Therefore, the use of lower temperature fermentation may minimize potential for cloudy or hazy wines by the end of primary fermentation.

 

http://extension.psu.edu/food/enology/wine-production/an-introduction-on-low-temperature-fermentation-in-wine-production

Edited December 12, 2016 by StringJunky

[Sensei]

The lower the temperature you ferment at the less volatiles are lost during fermentation which contribute to the bouquet and more subtle tastes.

 

Whisky is... distilled.. after fermentation..

[StringJunky]

 

Whisky is... distilled.. after fermentation..

Yes, those volatiles - having a lower boiling point - evaporate before the alcohol during distillation and will end up with it, contributing to the final taste.

Edited December 12, 2016 by StringJunky

[Sensei]

Yes, those volatiles - having a lower boiling point - evaporate before the alcohol during distillation and will end up with it, contributing to the final taste.

 

While doing distillation you throw away what is the first condensed as it contains methanol (b.p. 64.7 °C) and acetone (b.p. 56 °C)..

Edited December 12, 2016 by Sensei

[StringJunky]

 

While doing distillation you throw away what is first condensed as it contains methanol (b.p. 64.7 °C) and acetone (b.p. 56 °C)..

OK. I didn't know that. They must do it for making it easier to clarify then. Esters and aldehydes will be lower than those won't they?

Edited December 12, 2016 by StringJunky

[John Cuthber]

Keeping the fermentation cool(ish) has several advantages.

One is that you don't lose as much alcohol.

Another is that you lose less of the volatiles.

Most of the things that contribute to the flavour are less volatile than ethanol- but they are still volatile so they risk being lost.

There's also the issue that if the fermentation gets too warm it will heat itself and you get a loss of process control- that's not good for flavour or product loss.

 

I'm puzzled that a thread on whisky distillation includes this "Whisky is... distilled.. after fermentation..".

It's not as if anyone was unaware of that, so why say it?

"Whisky is... distilled.. after fermentation..

[StringJunky]

I'm puzzled that a thread on whisky distillation includes this "Whisky is... distilled.. after fermentation..".

It's not as if anyone was unaware of that, so why say it?

"Whisky is... distilled.. after fermentation..

I didn't realise the first distillation fraction was removed and took the lower temperature volatiles out, hence him saying that.

Edited December 12, 2016 by StringJunky

[Externet]

Isn't the mash what is distilled ?

[Sensei]

Isn't the mash what is distilled ?

Language purist..

Indeed, I should write:

"Whisky mash is... distilled.. after fermentation.. and clarification to get rid of dead yeast remains.."

 

OK. I didn't know that. They must do it for making it easier to clarify then.

Clarification of mash, is done prior distillation. It could take couple days.

We are using Bentonite

https://en.wikipedia.org/wiki/Bentonite

 

"Bentonites are used for decolorizing various mineral, vegetable, and animal oils. They are also used for clarifying wine, liquor, cider, beer, and vinegar.[2]

 

Bentonite has the property of adsorbing relatively large amounts of protein molecules from aqueous solutions. Consequently, bentonite is uniquely useful in the process of winemaking, where it is used to remove excessive amounts of protein from white wines. Were it not for this use of bentonite, many or most white wines would precipitate undesirable flocculent clouds or hazes upon exposure to warm temperatures, as these proteins denature. It also has the incidental use of inducing more rapid clarification of both red and white wines."

 

Esters and aldehydes will be lower than those won't they?

Methyl acetate has b.p. 56.9 °C.

Ethyl acetate has b.p. 77.1 °C, very close to ethanol 78.24 C.

Edited December 13, 2016 by Sensei