I recently tried my first open fermented Saison. My primary hope was that I would get better esters and phenolic character. Instead I got the opposite. I would say there are fewer Saison like flavors than I have experienced with similar recipes and the same yeast with regular closed fermentation. In addition to this the beer has a sulfur off flavor (h2s). I don't think I have ever made a beer where this level of sulfur. I have periodically been purging the keg while its in my keezer, and I would say the sulfur has dissipated a lot, but it is still there, and I don't know if it will fully clear out.
The open fermentation was done in a corny keg with the lid off and covered with a sanitized cheese cloth from day 1 - 3. Then the lid was replaced after the krausen fell down and finished as normal (albeit more quickly). It occurred to me that maybe I left things open too long, but I would think that the risk here would be oxidization. During krausen the wort temp free rose higher than normal (up to maybe 70f from the 65f temp I was trying to maintain (this is ambient temp during the day, and covered with a heating sleeve with ink bird and a neoprene cover over it to maintain temp at night.
Normally I would associate the sulfur production with stressed yeast. I suppose I have had period issues with mangrove jack yeast (its possible these were due to long shipping times, improper storage by the reseller, etc.), but could the stressed yeast have led to the low ester production as well? It is also worth mentioning that the beer reached high krausen very fast and attenuated very well. So, I am puzzled. I also do know that the ideal open fermentation scenario is to have a wide and shallow vessel to maximize oxygen exposure and reduce pressure, but I didn't have equipment available for that.
Does anyone have ideas about what went wrong, or advice for next time? Thank you.