oljimmy
Well-Known Member
Hi All
I recently conducted an experiment in order to try to isolate what was causing my pale beers to darken and develop sweet, sherry-like off-flavors in the bottle. I had 5 gallons of tasty, fully fermented IPA (1.057 to 1.009 in 3 weeks, 55 IBUs) which I bottled one month ago from a bucket in a variety of different ways (I used cooper's drops and cleaned/sanitized every bottle unless otherwise noted):
(3) bottles unwashed, unsterilized
(3) Bottles washed but unsterilized
(3) Bottles heavily aerated when 2/3rds full via shaking for 45 seconds
(3) bottles carbed using a dextrose solution
(1) bottle left to condition in the bright sunlight
(3) bottles carbed at ambient temps (70-85F) instead of in my 64F freezer
(1) bottled without any carbing sugar (to control for color)
The Results:
Three tasters recorded their impressions, then were blind triangle-tested in order to see if their impressions were reliable. We only kept the impressions that were widely shared amongst the four of us and that were "replicated" by tasters in a blind-fashion.
1. Bottles conditioning at 64 F were ready to drink in 5 days flat. Only a rare bottle or two needed a little more time.
2. Biggest surprise: the heavily aerated bottles were indistinguishable from non-aerated ones. This was confirmed by multiple blind taste tests. This lends support to the view that oxidation via aeration is not easy to achieve at this stage.
3. Unexpectedly, the unsanitized bottles had also lost some hop bitterness. Not sure how to explain that, but it certainly illustrates the importance of sanitization.
4. Finally, as expected, the bottle left in the sun developed a slight skunky flavor from the hops reacting to the sunlight. It was sweeter, presumably because its hop character was reduced.T his bottle was also *noticeably* darker, and interesting result I do not know how to explain:
All other Beer:
Sun-Conditioned Beer:
No other variables produced any results. The method of carbonation didn't matter, and only the sun-conditioned bottle developed any color differences.
Take these (nonscientific) results as you will, and I certainly learned a lot from the process. Sanitization and conditioning away from sunlight appear to be quite important. I won't worry quite as much about oxidation in the future, nor about conditioning temperatures.
I was not able to nail down the culprit re: my previous darkening problem, as all of these beers turned out great. I suspect that something in a bottling wand or in the bottling bucket was to blame.
I recently conducted an experiment in order to try to isolate what was causing my pale beers to darken and develop sweet, sherry-like off-flavors in the bottle. I had 5 gallons of tasty, fully fermented IPA (1.057 to 1.009 in 3 weeks, 55 IBUs) which I bottled one month ago from a bucket in a variety of different ways (I used cooper's drops and cleaned/sanitized every bottle unless otherwise noted):
(3) bottles unwashed, unsterilized
(3) Bottles washed but unsterilized
(3) Bottles heavily aerated when 2/3rds full via shaking for 45 seconds
(3) bottles carbed using a dextrose solution
(1) bottle left to condition in the bright sunlight
(3) bottles carbed at ambient temps (70-85F) instead of in my 64F freezer
(1) bottled without any carbing sugar (to control for color)
The Results:
Three tasters recorded their impressions, then were blind triangle-tested in order to see if their impressions were reliable. We only kept the impressions that were widely shared amongst the four of us and that were "replicated" by tasters in a blind-fashion.
1. Bottles conditioning at 64 F were ready to drink in 5 days flat. Only a rare bottle or two needed a little more time.
2. Biggest surprise: the heavily aerated bottles were indistinguishable from non-aerated ones. This was confirmed by multiple blind taste tests. This lends support to the view that oxidation via aeration is not easy to achieve at this stage.
3. Unexpectedly, the unsanitized bottles had also lost some hop bitterness. Not sure how to explain that, but it certainly illustrates the importance of sanitization.
4. Finally, as expected, the bottle left in the sun developed a slight skunky flavor from the hops reacting to the sunlight. It was sweeter, presumably because its hop character was reduced.T his bottle was also *noticeably* darker, and interesting result I do not know how to explain:
All other Beer:
Sun-Conditioned Beer:
No other variables produced any results. The method of carbonation didn't matter, and only the sun-conditioned bottle developed any color differences.
Take these (nonscientific) results as you will, and I certainly learned a lot from the process. Sanitization and conditioning away from sunlight appear to be quite important. I won't worry quite as much about oxidation in the future, nor about conditioning temperatures.
I was not able to nail down the culprit re: my previous darkening problem, as all of these beers turned out great. I suspect that something in a bottling wand or in the bottling bucket was to blame.
