stoutaholic
Well-Known Member
I've been looking into yeast fermentation performance and the research literature indicates that once yeast that have undergone respiration and have built up their reserves of sterols, they should be able to transition directly to anaerobic fermentation. This implies that if a sufficient number of yeast are propogated in an optimally oxygenated starter, it should be possible to pitch those yeast into an un-aerated wort with no undesirable effects, since the yeast have already synthesized all the necessary sterols and unsaturated fatty acids. Provided that an appropriate amount of yeast have been pitched, the fermentables in the wort should be exhausted before the yeast's sterol reserves. This would produce an extremely clean fermentation, since a host of undesirable compounds, including diacetyl, require oxygen in order to form.
So this brings up the practical question of how to pitch yeast at the height of their reserves, before they start exhausting those reserves in anaerobic fermentation. Since yeast will fully scavenge all dissolved oxygen before transitioning to anaerobic fermentation, it should be possible to oxygenate the starter to optimal levels (say 15 ppm), and then use a dissolved oxygen meter to determine precisely when the yeast have consumed all of the oxygen. At that point I could then pitch the whole starter into 5 gallons of wort.
Has anyone tried this approach? Can anyone think of any potential pitfalls that it would encounter?
So this brings up the practical question of how to pitch yeast at the height of their reserves, before they start exhausting those reserves in anaerobic fermentation. Since yeast will fully scavenge all dissolved oxygen before transitioning to anaerobic fermentation, it should be possible to oxygenate the starter to optimal levels (say 15 ppm), and then use a dissolved oxygen meter to determine precisely when the yeast have consumed all of the oxygen. At that point I could then pitch the whole starter into 5 gallons of wort.
Has anyone tried this approach? Can anyone think of any potential pitfalls that it would encounter?