Can someone explain how...

[ajdelange]

Another aspect of this I have neglected (I forgot about it) to mention is that photographs don't represent beer color very well if the beer appears dark either because it has a high SRM value or because it is a lower SRM beer but the light path through it is long. This is because, in either case, the color shifts towards pure (high saturation) red as the appearance darkens. This is a consequence of the fact that beer absorption spectra if normalized by the SRM are all pretty much identical and is why the SRM is a good measure of beer color. The resulting red colors quickly get outside the sRGB gamut used in computer monitors and so the color displayed is not the color photographed

 

[bmason1623]

Did you use sea salt or iodized salt?

Iodized salt can turn purple in the presence of acid or starch given a little bit of time. I had this happen to me with a batch of pickled eggs that I made once. I used iodized salt in my brine, and when it sat for a week or two, the contents reacted with the iodized salt to make everything in the jar purple! I guess that's why "pickling salt" is not iodized.

My guess is that you have a similar reaction happening in your beer from using iodized salt, which is reacting with the acid from your acidulated malt, or from unconverted starch in your beer. Check the packaging on your salt, and next time use pickling or sea salt for a Gose.

TB

maybe he didn't rinse the iodophor thoroghly and that caused a reaction?

 

[dirty_martini]

Hopefully this will give a better understanding of my confusion. On the left, the gose. One the right, the berliner. Both came from the same mash. Both were the exact same color going into the carboy.

 

[JoePro]

Refraction is not the issue here.

It's beer gnomes.

 

[ajdelange]

This at least gives me some idea about the colors of the beers. Were the illumination from behind consistent I could estimate the relative SRMs but because of the non uniform background and the refraction I can get SRM ratios anywhere from 2:1 to 5:1.

Just so I am sure I understand this you put a wort of about 5 SRM in a carboy and when you took it out it was at 15 or 20 SRM. Is that correct? If so, did the color develop over time or did it appear suddenly?

The only thing I can think of that could cause something like that to happen would be that you read that Gose is often served with syrup, put the syrup in and forgot you did it. Semi serious there. The only chemical explanation I can think of is oxidation and it would be a real stretch to think that natural oxidation could be responsible for such a deep color change.

Going back to the iodine theory for a moment:

IF you had a lot of unconverted starch and
IF the salt you used contained iodine at concentrations orders of magnitude higher than iodized salt does OR iodine came from somewhere else and
IF your beer was in a highly oxidized state and
IF the pH of the beer is less than 5.5 or so
then you could get a color such as this from iodine. Of these conditions only the pH condition is likely to be met but there is a simple test. Crush a campden tablet and add it to the beer. If the color is from iodine it will go away but if it is from any other oxidative process it will probably also go away. Simple enough test.

 

[dirty_martini]

Berliners are served with syrup, not goses. There was nothing added to the beer. The two beers looked exactly the same in their carboys. It was after it spent time in the keg carbing up that the discoloration happened.

 

[ajdelange]

Berliners are served with syrup but so are goses but that's not the point.

Ah, in the keg. That makes more sense. Suggests that there was some contaminant in the keg. This would be the best diagnosis at this point.

Try the campden tablet test. If a campden tablet clears the color we'll go on to DPD to see if it is from iodine. If it is, iodophor in the keg sounds like the most likely candidate but it could be any of dozens of things. Do you know the history of this keg? Have you cleaned it with caustic?