Fw: Rotten Egg Smell -Hydrogen Sulfide

[Guest guest]

from a post I have on file:

>

>

> Jack,

>

> " Rotten-egg smell " is due to the chemical, hydrogen sulfide. It is

the

> product of Sulfate Reducing Bacteria ( SRB ) in most domestic

encounters.

> SRB are very common bacteria, but they are anaerobes, meaning that

they do

> best in the absence of oxygen. Kombucha is a semi-anaerobic

ferment, at

> least after the cap thickens; so, SRB might not do very well in

it. The

> acidity of Kombucha will also inhibit SRB. SRB do well in your

lower

> intestine, in warm pipes and in the bottom of water wells and oil

wells.

>

> I have never had sulfide in my Kombuchas. I have been brewing for

many

> years. I have purposely introduced many microbes via fresh,

organically

> grown fruit. The resultant Kombuchas has never had an off odor

either. No

> sulfide was ever produced. This summer I tried Mulberry. It was

fantastic.

> I found that the Mulberry pigment is a good pH indicator, going

from blue to

> red as the pH is adjusted.

>

> I once received a Kombucha ferment for analysis that had a foul

odor, but is

> was not sulfide. This was a few years ago. That was the only

Kombucha sample

> that ever smelled bad. I have analyzed many samples over the

years.

>

> Some Kombuchas that I have received were incomplete according to

the limited

> array of organic acids that I found. It is possible that your

Kombucha has

> lost some of the microbial components, thus making it susceptible

to SRBs.

> This is purely supposition and I hope this isn't the situation

that you're

> in.

>

> Sulfide is forced out of solution by addition of a stronger acid.

Hydrogen

> sulfide is a very weak acid. Fill two glasses with water from a

sour well

> (water containing sulfide). Add a spoonful of Kombucha to one of

the glasses

> and stir. You will notice strong sulfide odor over the acidified

water.

> That's right, Kombucha will liberate sulfide from the water!

>

> It is possible that a small amount of sulfide was in the bottle

that you

> used and the addition of Kombucha forced it into the small

headspace above

> the Kombucha. The sulfide would probably be noticeable only on

opening the

> first time after bottling (assuming your brew was sufficiently

acid). This

> may be what happened to you.

>

> Please elaborate on exactly when you noticed the sulfide. There

may be

> another clue for us there. Are you getting good cap formation?

Is your

> Kombucha's pH below 3? These are indications of a healthy brew.

>

> Write back or shout on the telephone if you have any other

questions on this

> subject or the analysis of sulfide. By the way, I have been

analyzing

> sulfide for about 30 years.

>

> Zeph

> _____