Not surprised. Not much different from what I experienced with a pack of fresh pure pitch …doesn’t take a ton of yeast when they are healthy and ready to rock.
This weekend (Tuesday for me) I’m taking my second run at no stir starters with a pale and a stout. After those, it’s lager time. I’m not freaked out about doing it with a lager, but rather keeping an open mind. Honestly, I hope they turn out world class. Why wouldn’t I?
what is it about high krausen that is so important? does this allow the yeast to immediately start replicating when it is pitched into the wort? what would happen if it wasn’t high krausen? how long does this window of time (high krausen) typically last?
High krausen represents the peak activity of the yeast. It’s similar to when a fermenting batch is top cropped and pitched into a new batch at high krausen. The yeast are most active and healthy at this stage.
The timing has been discussed earlier in this thread.
I suspect there is something a little more to it than that. I believe I have read that early in the fermentation the yeast needs to drop the pH of the wort. I’m under the impression that the fewer yeast cells there are to start with the more difficult this process becomes. but perhaps yeast that are already actively replicating (high krausen?) is a different scenario. some detail on that would be nice.
I’ll let Mark chime in, but I suspect people may be overthinking this.
From Mr Malty aka Zainashef
"Q: At what point do I pitch the starter into the wort? A great deal of discussion rages over this topic. Should the starter be fermented completely, the spent liquid decanted, and the yeast pitched or should the entire starter be pitched when at the height of activity? Most yeast experts say that when propagating yeast, moving at high krausen is optimal. The time of high krauesen can range anywhere from a few hours to twenty-four or more. It depends on the amount of yeast added to the starter wort, yeast health, temperature, and several other factors. Doss says a starter made from an XL pack of yeast into 2 liters of wort will reach its maximum cell density within 12-18 hours. If you’re starting with a very small amount of yeast in a large starter, it can take 24 hours or more to reach maximum cell densities. For the average starter, let’s just say that the bulk of the yeast growth is done by 12-18 hours. I like to pitch starters while they’re still very active and as soon as the bulk of reproduction is finished, usually within 12 to 18 hours. This is really convenient, because I can make a starter the morning of the brew day or the night before and it is ready to go by the time the batch of wort is ready. "
It seems to me that they key controversy is stirplates. Zainashef has said they are the best, Mark says no. I know that stirplates work. I know that oxygenated shook starters with no stirplate work too, but I end up with a far better smelling pitch, and so far the main fermentation appears to take off faster and is more vigorous. But thats from just one trial so far.
I think the pitching rate is the second area of contention here. Mr. Malty recommends something around 0.75-1.5M cells per mL per deg plato. Here it is something more like 0.25M cells per mL per deg plato.
Earlier in the “yeast essentials” article, zainashef talks about needed cell count, but if you read it in context hes talking about repitching a harvested slurry there. A starter that is fermented out, crashed, and decanted is basically a harvested yeast slurry. Seems to me an amount of harvested slurry may have different requirements than active high krausen pitch.
that makes sense. I was just looking for the reason why so I can sleep well at night 
Curious to hear firstly how you plan on tackling the lager starters in this method, and secondly your results with the lager starters and batch tastings.
After reading this thread it looks like 1 pack of lager yeast into 1 L wort (shaken method) inoculated post shaking. Then fermenting around low 70’s to increase cell biomass, then once it reaches high krausen, chill to around 50F and pitch all into your cooled batch of wort. Obviously for a normal gravity lager (1.050 or so). Am I missing something here?
It still seems like such a small amount of yeast, but if there is increased health and vigor, then that may make all the difference.
I think you’ve got it there. Mark has said before that the only cell count that matters is the viable cell count.
You are overthinking the problem and treating it like black magic when the problem is one of basic biological science; namely, how do we ensure that our culture owns the wort? We do so by pitching enough cells to ensure that we reach maximum cell density before any invaders have a chance to take control of the wort. A yeast culture owns a batch of wort by lowering the pH below 4.6, which prevents a whole host of pH sensitive bacteria, including pathogens, from gaining a foothold in the wort. It also consumes all of the dissolved O2, which prevents wild aerobic microflora from gaining a foothold in the wort. Finally, a yeast culture produces ethanol, which is toxic to all carbon-based lifeforms at a given level. Brewing yeast cultures have been domesticated via selective pressure to be able to withstand the ethanol levels encountered in brewing. Most wild microflora cannot withstand the ethanol levels encountered in fermentation (which is why rinsing yeast with and storing it under boiled water is a bad idea).
A concept that brewer’s need to burn into their minds is that fermentation is controlled spoilage. The key word here is “controlled.” We want the pitched microflora to own the wort. The problem that we face is that the bacteria cell count doubles three times in the same amount of time that it takes for the yeast cell count to double, and no brewery is sterile. The difference in replication rates means that the bacteria cell count grows by a factor of 8 (2 * 2 * 2) every time the yeast cell count doubles; hence, we are looking at 8n and 2n growth models for bacteria and yeast respectively when we normalize the growth rates to the time it takes for the yeast cell count to double.
Here’s the reason why we make a starter:
yeast_cell_count_at_time_t = initial_cell_count * 2(t / replication_period_in_minutes), where t is the amount of minutes that have elapsed since the culture transitioned from the lag phase to the logarithmic phase
bacteria_cell_count_at_time_t = initial_cell_count * 8(t / replication_period_in_minutes), where the t is the amount of minutes that have elapsed since the culture transitioned from the lag phase to the logarithmic phase
Let’s look at a situation that we never want to have occur; namely, pitching so little yeast that the culture has to spend 24 hours in logarithmic growth in order to reach maximum cell density (this situation was common in the bad old days).
t = 1440 (24 hours into the logarithmic phase, or 16 replication periods because the average replication period for a yeast cell is 90 minutes)
2 raised to the power of 16 is 65,536
yeast_cell_count_at_time_t = initial_cell_count * 65,536
8 raised to the power of 16 is 281,474,976,710,656
bacteria_cell_count_at_time_t = initial_cell_count * 281,474,976,710,656
If the yeast cells do not own the media long before twenty-four hours of exiting the lag phase and our brewery is not clean enough to eat off of the floor, it’s all over; therefore, we want to ensure that the yeast culture never needs go through more than six to seven replication periods in order to reach maximum cell density (signaled by high krausen). The reason why we pitch at high krausen is because it shortens the lag phase, which starts replication earlier.
maximum_cell_density_for_1L = 200 billion
Most brewers who use 5-gallon soda kegs start 5.5 gallons of wort in the primary.
maximum_cell_density_for_5.5_gallons = 21 * 200 billion = 4.2 trillion (5.5 gallons is roughly 21 liters)
our_culture_cell_count_low = 50 billion
number_of_replication_periods = log(4.2 trillion / 50 billion) / log(2) = 6.4 replication periods (or 9.6 hours spent in the logarithmic phase)
our_culture_cell_count_high = 200 billion
number_of_replication_periods = log(4.2 trillion / 200 billion) / log(2) = 4.4 replication periods (6.6 hours spent in the logarithmic phase)
If a replication period is 90 minutes on average at ale fermentation temperature (64-68F), then our yeast cultures will saturate the wort within 6.6 to 9.6 hours after leaving the lag phase, making the time spent in the lag phase the hold up. When we pitch a culture that has sedimented (i.e., quiescent cells), we are pitching cells that underwent survival-related morphological (cellular) changes. They stored glycogen and the disaccharide trehalose. The also thickened their cell walls. It takes time after pitching for these changes to be reversed. Additionally, all replication past high krausen is for replacement only, and mother cells share their ergosterol and unsaturated fatty acid (UFA) reserves with their daughters and their daughters share their reserves with their daughters and so forth; therefore, allowing a starter to proceed past high krausen wastes ergosterol and UFAs. Ergosterol and UFAs are synthesized by the pitched yeast cells during the lag phase. The more ergosterol and UFAs a cell needs to replenish, the longer it remains in the lag phase and the higher the O2 load placed on the wort because these compounds are synthesized in the respirative metabolic pathway using O2.
Viable is the wrong word; you should also have > 90% viability after making a starter and letting it ferment out. I think the claim is that , since yeast at high krausen has not had to deplete reserves of various things needed for growth in preparation for dormancy, they are prepared to multiply more than yeast from finished fermentation.
one of the things I wasn’t sure of is if the yeast needed to change something about the wort environment before really doing their thing. what actually happens during the lag phase is somewhat of a mystery to me.
I’ll probably post the heck out of it when the time comes.
One can think of the lag phase as a period where the cells adjust to their new home and get ready for exponential (logarithmic) growth. The cells need to replenish their ergosterol and UFA reserves because these compounds make the cell membrane more pliable, which makes it easier for a cell to pass nutrients into and waste products out of the cell. Anything that impacts metabolism impacts replication as well as the ability to attenuate the extract.
Why does a 1 to 19 step seem like a small amount of yeast? Because some other brewer said that one has to pitch X number of cells per degree Plato per milliliter of wort? What is the basis for that metric? What were the environmental conditions under which the metric was developed? How clean was the brewery? What was the average age of the cells? What amount of hydrostatic pressure were the cells subjected to previously? Without this data, the suggested pitching rates are not very useful in a home brewery.
Commercial pitching rates take into account the high microbial loads encountered in commercial breweries as well as the fact that a large percentage of the pitched cells have been through more than one fermentation, not to mention have had to endure significant hydrostatic pressure in tall cylindroconical fermentation vessels. Young yeast cells are like young humans when it comes to the ability to reproduce. A 1L starter contains at least 50% new cells, and the old cells were grown under conditions designed to preserve health. In essence, a starter is a totally different beast.
As I have stated many times, what determines if a fermentation will proceed successfully are the health of the cells going into the fermentation, dissolved O2, and the amount of carbon (and nitrogen) available to the cells. If we pitch a small amount of cells that are in poor health into poorly aerated wort, we can expect less than stellar results. If we pitch a normal amount of cells into high gravity wort, we can expect less than stellar results because the effects of high alcohol and high osmotic pressure coupled with lower O2 solubility wreak havoc on the cells and reproduction.
I will add one more thing to this discussion for those who believe that a 1L starter is too small for a 5-gallon batch. Back in the nineties, Maribeth Raines and Jeff Mellem started a groundbreaking yeast company called BrewTek. BrewTek sold yeast on mini-slants and yeast culturing kits (Denny’s Favorite 50 started out as BrewTek CL-50). Guess what size Erlenmeyer flask shipped with the BrewTek kit (Denny, you are not allowed to answer this question)? I will give you a hint. It was not a 2L Erlenmeyer flask.
My guess is a repuposed half pint jelly jar.