Gaseous wort blow off

[troublebrewing]

OMG! Put the lids firmly back on?

[delboy]

Don't worry it'll be fine, the yeast will quickly exhaust the oxygen in the wort and kick into anerobic fermentaion, plus it will be under the co2 blanket preventing the wort from taking up any more oxygen.

I ferment most of my stuff with the lid cracked open and it still gets me drunk maybe its psychosomatic

[Jim]

Delboy's right - if leading the lid off stopped the yeast producing alcohol, commercial beer would all be alcohol-free!

[Paul_S]

I never snap the lid shut, and don't ferment under airlock - after all yeast needs oxygen to survive and do its job.

Hate to tell you this, but in the presence of oxygen yeast will convert sugar completely into CO2 and energy; if you want any alcohol keep the oxygen out.

'Tis true but the blanket of CO2 produced is heavier than air so will lay on the surface of the brew keeping most of the air away from it. Also, the yeast on the top of the brew isn't fermenting anything - that's the yeast in suspension doing the work.

Many commercial breweries ferment in open fermenters (eg. the late Hardys & Hansons, God bless 'em). The deep layer of CO2 effectively puts an invisible lid on the fermenter and also actively rouse the yeast every hour to keep it in suspension.

Personally I just practice the loose lid method & snap it closed once the head has completely collapsed. I've never bothered with an airlock - the slight positive pressure in the fermenting bin forces more CO2 into solution than at atmospheric pressure thereby keeping more condition in the beer which I try to maintain at racking by ensuring there is no splashing.