Sciencemadness Discussion Board

Black eggs

hkparker - 10-4-2011 at 14:43

A few years ago I spend part of my summer in Japan. There I got to see a volcanic spring where hydrogen sulfide spewed from boiling hot water :D. Anyway, at this site, you could buy eggs that had been hard boiled by the water in the spring. The eggs would go in white and come out black. They said it was because of a reaction between the shell and hydrogen sulfide, but I'm not sure what the reaction is. I googled around and found nothing (except <a target="tab" href="http://btr.michaelkwan.com/2007/12/11/black-eggs-add-years-to-your-life/">this article about it that doesn't go into the chemistry</a>;), so I was wondering if anyone knew what reaction H2S undergoes with eggs to turn them black.

Also, I once had some H2S in a ziploc bag as a byproduct of a reaction and I noticed the inside get dark...

food - 10-4-2011 at 16:19

<a href="http://dochoonho.sunchon.ac.kr/NICE2/2ndNICE-Papers/2ndNICE-posters/00022%20Shigeki%20Hiramatsu.pdf">Here's something regarding the chemistry.</a> From a search, I'm not familiar with these special eggs. I can never resist a google challenge.

edit: after looking at the other search results, I'm seeing that some ascribe the iron as being available in the springs water and some are saying that the eggs contain the iron. So maybe it's not as clear cut as the link that I included suggests. There is often a discolouration in hard boiled eggs that is apparently caused by iron sulphide. You'll need to test the waters on your next visit.

[Edited on 11-4-2011 by food]

The WiZard is In - 11-4-2011 at 09:06

Quote: Originally posted by hkparker  
A few years ago I spend part of my summer in Japan. There I got to see a volcanic spring where hydrogen sulfide spewed from boiling hot water [snip]



A different method. I remember seeing these for sale some
years ago on the street in NY's China Town.

http://en.wikipedia.org/wiki/Century_egg

I am told the Norwegians have a similar egg after it is dug up...!

hkparker - 11-4-2011 at 09:13

I read up on that, I think its a different reason they are turning black though, as H2S isn't present in the process for making century eggs.

bahamuth - 11-4-2011 at 10:41
Quote: Originally posted by The WiZard is In  
I am told the Norwegians have a similar egg after it is dug up...!


I have heard of no such thing here in Norway, but we have "grav laks" which would roughly translate to "dug" or "grave" salmon but it is not commonly fermented underground anymore. Also we have "rakfisk" which comes from Norse "rakr", which translates to "soft", which still is fermented underground.

As a trueblood Norwegian I have to admit neither is very appealing to the taste. But Asian fermented foods, atleast those I have tasted until now, are tastier.


Rakfisk
Gravlax

ScienceSquirrel - 11-4-2011 at 11:17

You have forgotten lutefisk!
Described by a Norwegian woman that I once knew as looking, smelling and tasting like shark snot.
Her Danish friend, the Danes do not make or eat lutefisk, would say;
'Take a fresh cod and bury it in a manure heap. Leave it there for several months, then dig it out and eat the manure heap!"

food - 11-4-2011 at 11:26

Quote: Originally posted by bahamuth  


But Asian fermented foods, atleast those I have tasted until now, are tastier.



OT. It's funny that you would mention that. I started preparing some soy beans yesterday to innoculate with a store-bought sample of 'natto'. This Japanese food post was what I saw when I got home from the store yesterday. If all goes well and I have a good culture I will try isolating it and perhaps post that. There is a fair bit of interest in bacillus subtilis 'natto' for different reasons.

'eat the manure heap!' , don't be giving me ideas

bahamuth - 11-4-2011 at 11:34

Quote: Originally posted by ScienceSquirrel  
You have forgotten lutefisk!
Described by a Norwegian woman that I once knew as looking, smelling and tasting like shark snot.
Her Danish friend, the Danes do not make or eat lutefisk, would say;
'Take a fresh cod and bury it in a manure heap. Leave it there for several months, then dig it out and eat the manure heap!"


HAHA.

Lutefisk may, if prepared correctly, taste quite something though.

But it is not fermented, but hydrolysed (lut = lye) traditionally with ash from leafy trees, so potassium carbonate. Nowadays sodium hydroxide is used, but the old people say it tastes best prepared from the correct ash. If not prepared correctly, which sadly few to none commercial producers do, it is reduced to a jelly like substance with no texture and just a fishy taste, really awful.

But we are digressing off topic....

The WiZard is In - 11-4-2011 at 11:51

Quote: Originally posted by ScienceSquirrel  
You have forgotten lutefisk!

Her Danish friend, the Danes do not make or eat lutefisk, would
say; 'Take a fresh cod and bury it in a manure heap. Leave it there
for several months, then dig it out and eat the manure heap!"

"Traditionally, the greatest varieties of kimchi were
available during the winter. In preparation for the long winter
months, many types of kimjang kimchi were prepared in early
winter and stored in the ground in large kimchi pots."

http://en.wikipedia.org/wiki/Kimchi

The WiZard is In - 11-4-2011 at 12:08

Quote: Originally posted by bahamuth  


Quote: Originally posted by The WiZard is In  
I am told the Norwegians have a similar egg after it is dug up...!


I have heard of no such thing here in Norway, but we have "grav laks" which would roughly translate to "dug" or "grave" salmon but it is not commonly fermented underground anymore. Also we have "rakfisk" which comes from Norse "rakr", which translates to "soft", which still is fermented underground.

As a trueblood Norwegian I have to admit neither is very appealing to the taste. But Asian fermented foods, atleast those I have tasted until now, are tastier.



What was described to me many years ago was balut/baalut.

http://en.wikipedia.org/wiki/Balut_(egg)