colonel2jays Posted June 13, 2019 Share Posted June 13, 2019 Hey all, has anyone ever experienced an increase in SG on their ferments? Yesterday (day 5) I had 1.009 and today I have 1.011! I've never seen this before. The product is a wheated bourbon-style mash with the grains separated from the wort prior to fermentation. The total volume in the tank is ~6000 litres, with 1480L of that having begun wild yeast fermentation two days before 4.5kg dry yeast was pitched. Is it possible that fermentation has stopped and somehow we're still getting secondary starch conversion? Thanks in advance! Link to comment Share on other sites More sharing options...
Tom Lenerz Posted June 13, 2019 Share Posted June 13, 2019 Did you temperature correct your sample? Earlier in the fermentation it will be hotter, and therefore read lower then if the same sample is cooled to closer to the calibration temperature on your hydrometer. Also a potential cause, were your first or second samples actually a representative sample? Link to comment Share on other sites More sharing options...
bluefish_dist Posted June 13, 2019 Share Posted June 13, 2019 I have had stratification, ie it’s not fully mixed and if you check by pulling off the top you get a false reading. The yeast mixes it up better and the reading goes up since the wort is now mixed and the denser wort is now evenly distributed. Link to comment Share on other sites More sharing options...
colonel2jays Posted June 18, 2019 Author Share Posted June 18, 2019 On 6/13/2019 at 10:17 PM, Tom Lenerz said: Did you temperature correct your sample? Earlier in the fermentation it will be hotter, and therefore read lower then if the same sample is cooled to closer to the calibration temperature on your hydrometer. Also a potential cause, were your first or second samples actually a representative sample? Tom, thanks for your reply. The temperature difference between the two readings was only 0.9C so that's not it. The samples were taken from a sample port about 18" from the base of the tank. I'd like to think that can be called a 'representative' sample. I even took a second sample of the 1.011 product as a sanity check. Link to comment Share on other sites More sharing options...
colonel2jays Posted June 18, 2019 Author Share Posted June 18, 2019 On 6/14/2019 at 12:08 AM, bluefish_dist said: I have had stratification, ie it’s not fully mixed and if you check by pulling off the top you get a false reading. The yeast mixes it up better and the reading goes up since the wort is now mixed and the denser wort is now evenly distributed. Bluefish, thanks for your reply. I certainly can't rule out stratification, but after 5 days in the tank I'd have thought all of the distribution of wort that was going to happen would have happened already! It's also important to note the gravity didn't change from 1.011 in the days after, so it's safe to assume the batch was no longer actively fermenting on day 6. Does anyone have any thoughts on my 'secondary conversion' hypothesis? Link to comment Share on other sites More sharing options...
Tom Lenerz Posted June 19, 2019 Share Posted June 19, 2019 Depending on your cook process, it is likely starches will continue to break down. As a result finished gravities can and often are below 1.000. The only way I could see a mash getting more dense (increased gravity) is if you lose alcohol. It seems more likely that your sampling procedures explain the variance. Link to comment Share on other sites More sharing options...
Silk City Distillers Posted June 19, 2019 Share Posted June 19, 2019 I vote for Tom's explanation. Occam's razor. Simplest answer is the often the right one. Measurement error. Link to comment Share on other sites More sharing options...
colonel2jays Posted June 20, 2019 Author Share Posted June 20, 2019 Thanks guys. Now to take steps to improving my fermentation performance... Link to comment Share on other sites More sharing options...
Dsking416 Posted July 15, 2019 Share Posted July 15, 2019 I feel like it's a measurement error or continuation of the enzymatic conversion. Some enzymes are still active as low as 70f. Link to comment Share on other sites More sharing options...
nabtastic Posted November 12, 2019 Share Posted November 12, 2019 sorry to resurrect Lazarus here but I wanted to chime in. also, a caveat: I imagine for most users on the form will not find this applicable but it does happen. - I noticed in the OP that wild yeast was a variable. This may or may not be relevant to your situation but I have had ferments where their SG increased, at least nominally. All of our ferments were wild and some would have further "infections" - particularly from a poorly cleaned sugar cane mill - would cause exceptionally thick, viscous ferments. Link to comment Share on other sites More sharing options...
Silk City Distillers Posted November 12, 2019 Share Posted November 12, 2019 Pediococcus - nice call Link to comment Share on other sites More sharing options...
Bakery87 Posted March 27, 2020 Share Posted March 27, 2020 With pedio over time you should be able to see with platelets on the top of the ferment, right? Was this a grain on or off fermentation? Depending on how the sample was prepared with grain present, that could change the reading. Usually with hydrometers it's an error as many others have pointed out. Link to comment Share on other sites More sharing options...
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