…but it would be equally inaccurate to discard lag time as one element — in combination with others — as an indication of yeast health and vitality.
While certainly a step in the yeast lifecycle, to suggest lag time is completely irrelevant gives an incomplete picture. In consideration of the strain, long lag times could be an indication of anemic growth and the reason(s) should be investigated.
Lag time, fermentation vigor, attenuation, smells and flavors (among others?) are all indicators used in combination to paint the complete picture of yeast health and vitality.
When you say “active”, what exactly do you mean? I always make starters, crash them overnight or during the brewday, then decant and pitch once it’s back up to pitching temperature. I never pitch the full starter, and like i said, I pitch after crashing, which would make me think the yeast isn’t exactly active even though there is plenty of it and it’s healthy. In my head, an active yeast pitch is a starter coming straight from the stir plate that is in active fermentation.
Actively fermenting, but no stir plate. I’ve come to the conclusion yeast vitality is much more important than cell count. Old Dog…New Tricks | Experimental Brewing
I’m not sure how one can make this statement.
A short lag time is THE indicator of yeast health and vitality and that you did your job properly as a brewer setting up a good environment for them.
There are definitely two schools of thought on pitching starters (decanting the liquid off the yeast after crashing, or pitching the whole starter) and neither one is better than the other IMHO. I always pitch the whole starter into my beer because I am a bit lazy about the extra step of refrigerating the starter and decanting off the liquid. Plus the yeast is already hot-to-trot in the starter medium and there are still some yeast cells in suspension, so why not use them all. I once posed this question at a long past Homebrew Con and the speaker answered by saying he would probably jut pitch the whole thing. I have decanted the liquid off the yeast cake in the past, added cooled wort from the brew day, and put the flask back on the stir plate while filling the fermenter. I saw no difference from what I now do and it is one less step I have to consider.
I almost always under-pitch a little bit and have never had any adverse problems. That said, I also agree with Denny’s comments when he quoted Chris White telling him that homebrewers are overly concerned with yeast counts.
But we can develop, empirically, valid proxies. Since my yeast harvesting and repitching procedure and schedule is pretty consistent, I have an intuitive guide to “pitching rate” based on volume of slurry. More for some beers, less for others. I don’t have any real idea of the cell count, but I know what works in my brewery. Likewise when propagating a new pitch, I know what volume works for what. So I think the underlying concept of cell count is valid, we just have to accept we are not approaching it directly, and admit that a little variation in what is anyway an unknown is not worth fretting about. If you follow a rule of thumb like “pitch half the old cake for lagers, a quarter for ales,” for example, you are making assumptions based on relative cell count, if not actual.
I used to do yeast cell counts when I did my pro-brewing gig. Yes, you can get really good empircal data from yeast counts and also good viability numbers at the same time to aid in re-pitching the proper amount of cells. I just don’t have the space to set up a lab in my brewery, buy an expensive microscope, hemocytometer, and methyl blue solution to do so. Things like Mr. Malty and past experience get me close enough on the homebrew front.
Hmmm, I am starting to take the Denny approach here. ;D
Regarding oxygen:
Low flow for shorter than you think should get you to sufficient oxygen (i.e. 0.25 lpm for 30 seconds in 5 cold gallons should give 8+ppm). Then again, for homebrewing the “realm of reasonable” is HUGE - from doing nothing, to mild shaking, to aquarium pump, to 2 lpm oxygen wand for 2 minutes - it’ll all produce a finished beer with little to no discernible difference. From a commercial standpoint, consistency in finished product is key and yeast health is very important from an expense standpoint, therefore the steps required are dictated differently than at home.
Regarding yeast:
Same as oxygen. You’re throwing grenades at the wort - even somewhat close is well within the margin of error for screwing up the batch. But again, from a commercial standpoint, things are dictated differently than at home.
Sometimes the more you know, the less you know.
Ignorance can truly be bliss in homebrewing ;D (not so much in commercial brewing ) - luckily this is a hombrewing forum!!
Regarding sanitizing a .5 micron stone, I spray starsan down the tube and on the outside, then I push the starsan out of the stone with O2 before I oxygenate the wort. Once the foaming subsides, place the wand in the wort and oxygenate. I haven’t examined the stone with a microscope, but I think this will sanitize the stone from the inside out.
) - luckily this is a hombrewing forum!!