If his water is especially alkaline, it can give the beer a soapy flavor. Id’ let the stuff go a full month for caarbonation to be done, and then evaluate it. If its still flat the it may just be yeast that he’s tasting.
He used RO water I’m finding out that his fermentation temp may have gotten to warm for one thing he left it for a full 2 weeks in the primary which also could have been a cause of his soapy taste it’s only a 1045 beer.
“Soapy flavors can caused by not washing your glass very well, but they can also be produced by the fermentation conditions. If you leave the beer in the primary fermentor for a relatively long period of time after primary fermentation is over (“long” depends on the style and other fermentation factors), soapy flavors can result from the breakdown of fatty acids in the trub. Soap is, by definition, the salt of a fatty acid; so you are literally tasting soap.”
Thats great in theory but I don’t find it to happen in real life. I’ve had stuff on trub for over a month and no sign of soap. And in any case its not the breakdown of fatty acids its the breakdown of triglycerides into free fatty acids where the fatty acids combine with potassium to form salts that are soap.
I think its a product of elevated ferm temps that produced something that tastes a little like soap.
I also read that in his book and I’m pretty well convinced that it was the temp he let get to high.
He’s going to let the bottles sit for a few weeks and in the mean time he is going to re-brew it and put the carboy in a laundry sink with water so he can monitor the temp. He didn’t know that it was that important, guess I must not have schooled him well on it.
He did tell me tonight that he has a heat tape on it a he thinks he saw the 80 light up and maybe a little more.
Keep us up on how the flat-ness turns out. I’ve had a bottling or two come out similar, though not necessarily “soapy” they tasted bad. Wrong temps can certainly cause the yeasties to produce chemicals besides CO2. If the flat-ness persists, I’d vote with ferm temp being the culprit.