In dropping the fermenting beer, oxygen is deliberately introduced to reinvigorate the fermentation, but some yeasts also produce diacetyl from this. This is part of the profile in some beers, but I dislike it. Yeasts that require this shot of O2 are also selected by this process and if they don’t get it, they tend to under attenuate. As a homebrewer, I often used it to speed up the whole process, but I had to choose my yeast accordingly.
In dropping the fermenting beer, oxygen is deliberately introduced to reinvigorate the fermentation, but some yeasts also produce diacetyl from this. This is part of the profile in some beers, but I dislike it. Yeasts that require this shot of O2 are also selected by this process and if they don’t get it, they tend to under attenuate. As a homebrewer, I often used it to speed up the whole process, but I had to choose my yeast accordingly.
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