Bottle-to-Bottle Off Flavors

[Pancoastbrewing]

I posted this in the all grain forum and had no replies...

Brewed a 3 gallon AG Munich Helles. Used 2 saflager s-23 dry yeast packets. Had a normal fermentation (52 degrees on the temp controlled fermenter) and a 35 day lager period. 3 weeks room temp bottle carb. Came out very well for the most part. Only issue is that I'm noticing some bottle to bottle inconsistency which I haven't experienced before. This is my first time using s-23 (usually use saflager 34/70) and I expected it to be a bit more fruity. I've noticed that most bottles have a slight sulfury aroma (somewhat ok for a Helles), while some have a strong banana-y, almost Hefeweizen type aroma and taste. Reminds me a lot of franziskaner hefe. It really tastes like two entirely different brews. There are no other noticeable differences between the sulfur and banana bottles as far as color, clarity and sediment.

Any ideas what might be going on here? I'm stumped.

 

[VictoryAle]

If this happened to me, I think I would suspect that the banana-y bottles were perhaps not properly cleaned and sanitized, and that there is a wild yeast, or bacteria in there, continuing to ferment the beer, creating phenols/esters.

 

[Pancoastbrewing]

If this happened to me, I think I would suspect that the banana-y bottles were perhaps not properly cleaned and sanitized, and that there is a wild yeast, or bacteria in there, continuing to ferment the beer, creating phenols/esters.

This is certainly possible, although I usually am pretty careful about thoroughly rinsing used bottles with hot water and regular dish detergent (I know I know). Then I let the bottles and caps soak in a water/starsan combination for a few minutes before bottling. If I had a dishwasher, I'd use that to clean the bottles, but I'm not sure that's where the problem is occurring.