The cleaning routine that ended my sour batches
Last spring two batches in a row went sour. Not pleasantly sour; a thin, tart edge that got stronger in the bottle, and in the second batch a wrinkled white skin across the surface of the beer when I lifted the lid at week two. I had been cleaning the way I always had, which clearly was not well enough, so I pulled everything apart to find the culprit.
The fermenter was a plastic bucket I had used for about forty batches. Under a flashlight the inside walls were covered in fine scratches from years of scrubbing with a brush, and the spigot at the bottom, once I took it apart for the first time ever, had a brown film inside the valve body that no amount of soaking had reached. I am fairly sure that spigot was the source. The bucket went in the recycling, and the beer that followed it went to the drain.
The routine I use now, written out so I actually follow it:
- Immediately after racking or bottling, rinse everything with hot water, then fill with a hot percarbonate cleaner at about a tablespoon per gallon and leave it overnight. Rinse well in the morning.
- Take apart every fitting with a moving part: spigots, airlocks, racking cane tips, bottling wand. Soak the parts separately in a small bowl of the same solution.
- Replace soft tubing twice a year regardless of how it looks, and the moment it clouds.
- On brew day, sanitize with a no-rinse acid sanitizer, two minutes of wet contact minimum, and keep things wet until used. Sanitizer only works on clean surfaces, which is the whole point of the night before.
I also changed a few habits that had nothing to do with equipment. I used to pour hydrometer samples back into the fermenter to save beer; I now drink them or dump them. I clean the kettle the same afternoon instead of leaving it with a ring of hop sludge until the next weekend. And the wine thief and sample jar get sanitized every time they go near the beer, not just at the start of the day.
The new fermenter is a glass jug with a wide mouth and a silicone lid, no spigot. Siphoning is slower than opening a tap, but there is nowhere for anything to hide, and I can see the inside under a light. Six batches later, no pellicle, no tartness, and the beer finishes where the yeast says it should.