Sulphur smell

[terrym]

That's rich!

My original post stated ...

"In this case, the yeast MAY be producing hydrogen sulphide (H2S) ..."​

... and that statement still stands as supported by all the Google hits I quoted. (I even highlighted the word "may" in the original Post.)

The Post carried on with ...

"The Hydrogen comes from the breakdown of the H2O (i.e. water)."​

... and that statement still stands in that H2O is broken down during the brewing process.

The brewing process itself breaks down the water molecule to produce ethanol. The formula for the production of ethanol from sugar finishes as ...

C6H12O6 > 2 C2H5OH + 2 CO2​

... but there is an intermediate stage where the enzyme Invertase gets involved as per ...

C12H22O11 + H2O + invertase > 2 C6H12O6​

My original Post went on ...

"A common source of Sulphur in brewing is the gypsum (CaSO4) used in water treatment."​

With regard to the sources of sulphur, are you saying that:
A) Gypsum isn't used in water treatment? or
B) There is no sulphur in gypsum?

The reason I ask is that gypsum is not "very chemically stable" as you state. In the 1970's gypsum was used for the commercial production of sulphuric acid as per ...

"Upon being mixed with shale or marl, and roasted, the sulphate liberates
sulfur dioxide gas, a precursor in sulfuric acid production ..."​

Finally, I DID NOT suggest that "the offgas from a yeast fermentation is sulphur toxic". From explaining that the smell of rotten eggs MAY be coming from the production of H2S I went on to explain (accurately) the properties of H2S after pointing out ...

"In this case, the yeast may be producing hydrogen sulphide (H2S)
in VERY low quantities due to the change of sugar."​

The VERY was already in capitals and highlighted. I suppose I could have put in "VERY, VERY, VERY small quantities" but I pre-suppose that the people on this Forum are intelligent.

Over to you, but I am backing out at this stage because I don't have anything more to add. :thumb: :thumb:

References:

https://en.wikipedia.org/wiki/Ethanol_fermentation
https://en.wikipedia.org/wiki/Calcium_sulfate

Dutto
I hope you haven't gone off in a huff.
1. I've never said that H2S (or any organic sulpur compound) isn't a by product of fermenting yeast. And I said that in my last post. And I'll say it again.
2, What I did say, however, for the third time, is that it is impossible for yeast to generate H2S from CaS04 and H20, which is what you implied in your OP. But if someone wants to provide proper evidence to the contrary I will admit I am wrong.
3. I have never said anything about gypsum not being present in brewing water. It may be there in the brewing water certainly if you add it as a water treatment chemical as I have done in the past.
4. I said in my OP that there was atomic sulphur present in CaSO4. I have known that for about 55 odd years.
5. Sulphuric Acid production is nothing to do with H2S. It's all to do with S02 and primarily SO3. And most sulphuric acid is made the Contact Process (where the starting block is elemental sulphur) or at least it was when I last worked on a fertilizer works where it was produced.
6. And that's me done too :thumb:
Kiss and make up?

 

[Dutto]

........... I last worked on a fertilizer works where it was produced.

.........

Life's too short to get the huff! :thumb:

Not quite "snap" but back in 1980 I helped to train the lads that commissioned and operated the Shedgum Gas Plant in Saudi Arabia. The plant produced 1,000 tonnes of elemental sulphur per day from 1.6 billion cubic feet of sour gas with an H2S content of up to 45%. (% not ppm!)

One great memory of that job was when I was taking a bunch of trainees out on site after the Plant was up and running. I was giving my usual pre-site lecture that started "You MUST know where the nearest Breathing Apparatus set is at all times ........ " when I noticed the lads were grinning and exchanging looks.

I was NOT amused, so I asked them what was so funny about a situation that was potentially lethal.

A lad called Adnan Tahir chose to answer for the group and said ...

"You always tell us that we have to know where the nearest BA Set is,
but you are wrong. We all know that when we are on site with you we
need to know where the second nearest BA Set is located."
:whistle: :whistle: :whistle:​

Oh, how right he was! :thumb: :thumb:



PS

Yet again, a perfectly innocent English word falls foul of Political Correctness!

I've just discovered that I can't use the word "s n i g g e r i n g" ...
... presumably because six of the letters make up a word that is considered offensive.

That the word is considered offensive is mainly due to a lack of education as it was originally used to describe a person who came from the area around the River Niger in Africa.

I suppose the town of Scunthorpe will have to change its name before much longer! :whistle: