Impact of Delayed OG Measure

[Heineken]

I brewed a Hefeweizen last weekend but forgot that I had broken my hydrometer the last time I used it. I went ahead and put aside some wort and left it in a open measuring cup on my desk until I got a new hydrometer. About 4-5 days later, I measured the OG and it came in at 1.044. This appears low to me as I was shooting for about 1.054. I might have had low efficiency, which wouldn't be the first time. However, was curious whether waiting to measure might have impacted the OG reading. Possible for a wild bacteria or yeast may have started a small fermentation?

 

[remilard]

I brewed a Hefeweizen last weekend but forgot that I had broken my hydrometer the last time I used it. I went ahead and put aside some wort and left it in a open measuring cup on my desk until I got a new hydrometer. About 4-5 days later, I measured the OG and it came in at 1.044. This appears low to me as I was shooting for about 1.054. I might have had low efficiency, which wouldn't be the first time. However, was curious whether waiting to measure might have impacted the OG reading. Possible for a wild bacteria or yeast may have started a small fermentation?

If you run into this situation again, freeze the wort.

Yes a fermentation could have started. I am not intimately familiar with the metabolism of any potential organism that can ferment wort but in general at that point (10 point drop) substantial amounts of organic acids would have been produced and you could confirm this by tasting (it doesn't taste like fresh wort) or pH measurement (but you don't know the pH of the fresh wort, I assume, so this would be a guess).

 

[Bmorebrew]

That it was left in an open measuring cup is fortuitous. If possible, look for a ring above where the liquid is now. You may be able to calculate the amount of water lost to evaporation and use this to figure out what the gravity would be if it were still at the same volume. I don't know if you would experience a 10 point difference over a five day evaporation, but try the calculation anyway.

 

[remilard]

Ahh, I missed the open part. It is probably evaporation but then it is almost certainly hosting bacteria and yeast (maybe not enough yet to have fermented it much).