Recent Experiments Fermenting With and Without a Starter

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micraftbeer

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I recently did a hands-on review of a stir plate and Erlenmeyer flask from MoreBeer. As part of that process, I brewed a number of batches to test out the benefits/effects of using a starter. My first two batches showed little to no effect of the starter on either fermentation parameters or finished beer taste. After some research, this seemed to make sense because of what they were- regular gravity ales made with good/fresh yeast packs. So I then brewed a couple of lager batches and challenged the fermentation a lot more with older yeast, higher gravity, and colder fermentation temps. These showed the difference/effect of the starter.

Below is a link to the review, which has plots within it of Tilt hydrometer readings throughout the fermentation of my batches. I brewed one big batch and then split it into multiple fermentors and pitched the respective yeast samples. I thought it was interesting to have data that showed when and how starters were effective.

http://www.homebrewfinds.com/2018/12/hands-on-review-morebeers-fermentap-magnetic-stir-plate.html
 
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This experiment is totally invalid due to poor study design (internal validity) and poor applicability (external validity).
1. The yeast was past the best by date.
2. You used different fermentation conditions for the batches -- temperature and oxygenation.
3. You used different lots of yeast.
4. The only outcomes you measured were fermentation speed and attenuation.
5. How many brewers have the equipment to control temperature for a lager fermentation but use expired yeast with no starter?

Should have let both batches ride under the same fermentation conditions and used the same yeast lot for both batches. Blind tasting preference of a panel AND fermentation speed would be a good outcomes to measure.

Evaluating literature and study design is a large part of my profession.

Curious, do you make much from those affiliate programs? Been thinking about doing something similar.
 
@RPh_Guy , you said the experiment was "totally invalid", but based on your response, it seems rather like you're saying it's "totally uninteresting". You say your work has you evaluating literature and studying design. I'm guessing you have constructed and run experiments yourself. And as such, you surely understand that to generate an experiment that is totally void of confounding factors is not always possible. Let me walk through what it was I trying to evaluate here, and I'll point out the known confounding factors and explain why I did it this way. You may still find it "totally uninteresting", but here it goes.

First, to answer a couple of your rhetorical questions that you claim makes the whole thing invalid. You claim/imply that getting yeast that is at the fringes of its "best buy" date is rare. When I'm using popular strains, I wholeheartedly agree with you. I've never seen an old pack of WLP-001. However, when I wander off the beaten path in yeast selection, it's not uncommon to find something that's 6 months old. If you stick just to the main staples, you may never encounter this. But I specifically wanted to show that by using a starter, you can create value even with these yeast pouches at the fringes.

The other statement you make is that it's illogical to presume there are homebrewers that have fermentation temperature control, but don't make yeast starters. But I am one of those. Starters represent extra work, drawing my brew day out into another day. Whenever I brew, I'm usually dodging between various family responsibilities. Having to do that on brew day plus an evening a couple days ahead of brew day, makes it more challenging for me. So for years, I never made one- and I have & use fermentation temperature control. So we do exist. Maybe I'm the only one.

For the first experiment with the Black Lager, I specifically planned a higher OG brew, and wanted to ferment at colder temps to make it more challenging for the yeast. The 1 month past the "best buy" date was not planned, and was an excellent case in point of getting yeast past the expiration date. I found when I got home from the LHBS that they both were old. It worked as a bonus for me in this experiment.

For this experiment, I had no way to not use 2 different packs of yeast and do the test I was running. If I used one yeast pouch and split it in two, I would be way short-changing the fermentation that didn't have a starter and would make results of that invalid due to unrealistically under-pitching. I could have mixed the 2 packs and split them in two, but I wasn't confident of being able to accurately split them in equal yeast cell amounts so I didn't want that to affect my results. So I proceeded with 2 different yeast packs. I felt the one smack pack without a starter was representative of how I've brewed/fermented for years (being an anti-starter guy).

You mentioned that they were fermented at different temperatures, but they weren't. I tried to summarize my experiment as briefly as I could, and it appears I over-simplified on this point. Both were fermented in identical fermentation temperature control setups (BrewJacket immersion rod) and held at a steady 50F. While the batch with the starter kicked off and started fermentation after about a day, the batch without the starter had no activity after 4.5 days. At that point, I concluded it wasn't going to start unless I got involved in other ways to get it going. That's when I started raising the temperature.

My conclusions from this experiment: 1) Old yeast can still be used successfully to brew a challenging fermentation if you use a starter, 2) Old yeast and no starter will force you into compromises on fermentation and you might not get what you want out of it (case in point, I couldn't get fermentation to start until 64F instead of my desired 50F.

The second batch for my experiment with the Pilsner had similar results. But in this case the batch without the starter had a yeast pack that was still good for freshness, but the batch with the starter had an out of date (or borderline out of date) yeast pack. My conclusions from this experiment are same as the first experiment but showed that it still holds true when comparing an "in date" to an "out of date" yeast pack. In this case, I obviously couldn't use the same yeast.
 
Didnt read your experiment, but makes sense. Thanks for sharing your work. Iirc, much to the chagrin of some, its all but a given fact that in many cases a yeast starter isnt really a huge upgrade. You mention one case where no doubt it is. Its my understanding a starter will take off faster. Also I read somewhere it is connected to lodo brewing, dunno. But glad to have some more data points. We should all be able to agree that a quality fresh pack of dry yeast in todays day and age is ok to use with little to no concern in many cases.
 
it seems rather like you're saying it's "totally uninteresting".
I suppose that's accurate.
I'd be more interested in whether making a starter improves beer quality or produces any noticeable difference in the final product.
E.g. replicating this: http://brulosophy.com/2015/04/20/yeast-pitch-rate-single-vial-vs-yeast-starter-exbeeriment-results/
"Frankly, for a beer I was very nervous about, given the early fermentation being so sluggish, I was pleased at how subtle the differences between the beers ended up being and enjoyed drinking both batches."
also http://brulosophy.com/2017/10/16/ye...-starter-in-high-og-wort-exbeeriment-results/
and http://brulosophy.com/2018/09/03/ye...h-in-high-og-belgian-ale-exbeeriment-results/

Your results indicate that starters likely decrease lag time of expired lager yeast at traditional lagering temperature. That's completely expected because starters are well-known to increase cell count.

Thanks anyway for sharing. Hope you enjoy your new stir plate!
 
I'd be more interested in whether making a starter improves beer quality or produces any noticeable difference in the final product.

You may have overlooked this statement in my write-up on the Black Lager "That batch also suffered from unwanted flavor harshness from fermenting at too high of a temperature." Of course we'd all prefer to have 30 taste testers like Brulosophy experiments to generate statistically relevant subjective feedback on these types of things.

You're excellent feedback also reminded me that I now have both finished batches of Pilsner Urquell to do taste comparisons on, and I can update my review. I won't have a 30-person panel to review it, so I'm sure I'll still get the "totally invalid" line from some. Initial tastings show the one that had to get heated up to start fermenting was pretty nasty, but I'll do the blind review and get some better comments.
 
Thinking about @RPh_Guy comments on my experiment on my drive into work had me confused on which parts of my experiment were criticized, and which parts were found to be missing. To me, I think the more value-added experiment was to prove/quantify the value of the yeast starter process, as it consumes a few hours of time making/chilling a couple of days prior to brew day. But that was suggested to be useless information because everyone knows starters are great. But what was put forward as a more valuable experiment would be to get a large group blind taste test of a lager fermented at 50F, compared to a lager fermented at 64F. Other than being able to thumb your nose at the brewing industry and yeast manufacturers that publish recommended fermentation temperatures, I don't understand the value in that. Unlike the process of making a starter that requires more time input by me, I just set my fermentation temperature control to a different target temperature. The colder temperature will take a few days longer to ferment than the warm fermentation, but that just requires patience. It doesn't require me to do extra work.
 
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I don't think you were attacked he agreed with your response of it not being to his interest.
And just a side note there are millions of people on the internet all with different opinions you should never let anyone else's comments bother you unless your being threatened :mug:
 
I don't think you were attacked he agreed with your response of it not being to his interest.
And just a side note there are millions of people on the internet all with different opinions you should never let anyone else's comments bother you unless your being threatened :mug:

Good point. I edited my previous post to eliminate my guesses of his intentions... @OG-wan Kenobi you are a wise counselor!
 
The essence of experiments is to control all variables except the one in which you're interested. Treatment batch and control batch should differ by only that one variable, and thus, you can (if done correctly) unequivocally attribute differences between the resulting batches to just that variable.

But if, for instance, you oxygenate the batch into which you pitch the starter, and don't oxygenate the batch into which you pitch the non-starter, to what can you attribute the differences? Oxygen? Or starter? Or a combination?

You simply can't separate the influences.

The Brulosophy experiments are, IMO, pretty well done. I tend to have a high degree of confidence in their experimental processes, assuming what they tell us they do is what they do....and I have no reason to believe otherwise.

My issue with the Brulosophy stuff has always been the testing. The panels aren't consistently constituted, we don't know to what population they generalize, we don't know if testers have been drinking taste-bud-killing IPAs before testing, or eating garlic fries, or if their palates are clean....and they don't present the beers in a way to reduce or eliminate ordering effects.

In OP's case, if all he's measuring is speed at which the fermentation takes off, then the flavor results aren't necessarily important. I virtually always do starters and oxygenate the wort because I get much faster fermentation, and that's a major way to fight infections, i.e., the yeast outcompete them. Slow is bad in my world.
 
@mongoose33 is right

The experimental variable was making a starter vs direct pitching. Ideally this would be the only difference between the two batches of beer.
Let's call the direct pitch batch the control batch.

A confounding variable right from the start is the use of different yeast packs, presumably from different lots (you didn't mention anything about the lot number with the black lager).

Up until 4.5 days both black lager groups were treated the same and you successfully determined that the experimental batch had decreased lag time.

At that point you made an intervention on the control batch -- increasing the temperature and adding oxygen. All results after that are inconclusive because they can't be attributed to the experimental variable. Thus we don't know from this experiment how the experimental variable affected the final beer.

Same thing occurred with the pilsner.

You said it yourself, the harshness in the black lager was probably from the increased temperature, and not as a direct result of the experimental variable. You did not need to increase the temperature for the control batch. It was working at its own pace and may have finished the same as the the experimental batch if not for the other variables.
 
In much fewer words your experiment does not adhere to scientific standards.
 
@mongoose33 is right
Thus we don't know from this experiment how the experimental variable affected the final beer.
We actually know that yeast in good shape and numbers do a better work. Chris White has a beautiful graph about it in his book on yeast. But, well, we all know that, don't we?
 
In much fewer words your experiment does not adhere to scientific standards.

That's true, but both @RPh_Guy and I are trying to explain why without, hopefully, sounding condescending. Everybody's got their own areas of expertise; this just happens to be a place where we know something about the subject. And I hope @micraftbeer keeps doing experiments, tightening up the methodology as he goes.
 
We actually know that yeast in good shape and numbers do a better work. Chris White has a beautiful graph about it in his book on yeast. But, well, we all know that, don't we?
Brewers care more about taste than fermentation speed or any numerical metric. That's why we don't all crank temperature up to 95°F to have fermentation done and the beer packaged in a day.

I haven't seen a graph of pitch rate (low to high) vs taste (bad to good). Did I miss it?

As a counterpoint to the belief that pitching higher is always better, some styles can benefit from underpitching: hefeweizen, belgian sours, and kveik as examples.

Starters and pitch rate are simply one tool to affect fermentation speed and possibly flavor, depending on the yeast. Effect on flavor is not a simple matter due to the large diversity of yeast strains, diversity of wort composition, lack of controlled experiments, and the simple fact that we all have differing tastes and preferences.

I definitely welcome more experimental data to help make decisions about pitching rate, temperature, and other variables to help coax certain flavors (or lack thereof) from specific yeast strains.

It's a given that starters decrease lag time.

Cheers
 
I don't have any new data to add to the discussion, but I've had a bunch of beers pinged in competition for subtle fermentation-derived off flavors this year and I was getting pretty sick of it. Now I make starters every time and my beer seems better as a result.

Basically I don't trust the handling of the yeast from when it leaves White Labs / Wyeast and arrives at my door. We have a few White Labs approved partners now in New Zealand which is good, but I've still had almost new pure pitch brews get pinged in competition for fermentation issues (I know my temp control is solid). Also it is very common to be getting 4-6 month old liquid yeast. White Labs say their yeast is good to direct pitch up to the expiry date, that hasn't been my experience at all.

The benchmark that I aim for is krauesen on the brew and pressure on the dial the morning after brewday, if not same day. If it's 24h before this happens then I would consider that an underpitch or issues with the yeast health. YMMV of course.
 
OK, good healthy discussion on experiment set-up, variables, etc. I'm interested in hearing feedback from some of the folks on here on how they would go about conducting an experiment trying to prove/disprove the following hypotheses. It's easy to point out flaws in an experiment, but sometimes harder to come up with a foolproof one. Even the Brulosophy experiments are littered with people's comments about how this variable wasn't controlled and such. So these are the 2 hypotheses I put forward as my experiments support, but I'm interested in the holes in my logic and suggestions of how others would go about proving this.

Hypothesis #1: A yeast pack close to/just past its "best buy" date can still be used to ferment a challenging brew (OG > 1.050, 50F fermentation temperatures) if you use a starter. The same wort fermented just with the smack pack and no starter is not viable due to inability to start at 50F, and requiring intervention (higher temperature).

Hypothesis #2: Even a fermentation with an at/past "best by" yeast pack can ferment a challenging brew (50F fermentation temperatures) better than the same wort fermented by a yeast pack within its best buy date used without a starter.

Note that everyone has been commenting on lag time. I'm not trying to prove a lag time difference. I'm saying that I threw in the towel at ~4 days post pitch with no activity and had to come up with alternate fermentation parameters. I'm not necessarily trying to compare the flavor of a given yeast fermented at different temperatures, I'm saying that the brewer loses control of their fermentation profile by choosing to skip on the starter.
 
OK, good healthy discussion on experiment set-up, variables, etc. I'm interested in hearing feedback from some of the folks on here on how they would go about conducting an experiment trying to prove/disprove the following hypotheses. It's easy to point out flaws in an experiment, but sometimes harder to come up with a foolproof one. Even the Brulosophy experiments are littered with people's comments about how this variable wasn't controlled and such. So these are the 2 hypotheses I put forward as my experiments support, but I'm interested in the holes in my logic and suggestions of how others would go about proving this.

Hypothesis #1: A yeast pack close to/just past its "best buy" date can still be used to ferment a challenging brew (OG > 1.050, 50F fermentation temperatures) if you use a starter. The same wort fermented just with the smack pack and no starter is not viable due to inability to start at 50F, and requiring intervention (higher temperature).

Hypothesis #2: Even a fermentation with an at/past "best by" yeast pack can ferment a challenging brew (50F fermentation temperatures) better than the same wort fermented by a yeast pack within its best buy date used without a starter.

Even these are going to be hard to demonstrate convincingly, in that you have to have some idea as to how the yeast was treated before you received it.

The problem here is being able to potentially replicate the results. When you get a result using these hypotheses, does the fact that it does or doesn't work a single time signify anything?

I'm not sure there's meaning here anyway. I know that I can take a yeast pack that is near expiry, do a starter, then do my accelerated schedule. You may not like the schedule, but I would never brew a beer using the methods in your hypotheses.

I'd make a single starter and try to have it at 70 degrees about 16 hours after I began the starter. That's when I'd pitch it into 70-degree wort. I'd hold it there for 6 hours, then begin the drop to 50 degrees.

Then when fermentation is halfway complete, I'd ramp it up to 66 degrees (4 degrees every 12 hours) to finish. Who among us dump the whole starter in the fermenter? Well, me, and I think a couple others here, but usually people crash it and decant the beer.

Now, far be it from me to tell you how to enjoy the hobby--one of the beauties of this is we get to do exactly what we want, and why not? But I'm not sure the results would be helpful. I'd never consider doing a brew like you propose without a starter, so I'm not sure what the results would mean.
 
Hypothesis #1: A yeast pack close to/just past its "best by" date can still be used to ferment a challenging brew (OG > 1.050, 50F fermentation temperatures) if you use a starter. The same wort fermented just with the smack pack and no starter is not viable due to inability to start at 50F, and requiring intervention (higher temperature).
Let's try this:
Hypothesis: When pitching expired lager yeast at 50°F in high OG wort, making a starter reduces lag time to under 48 hours, and without a starter it lags greater than 48 hours.
Use the same lot of yeast, identical wort, and identical fermentation conditions. Measure the lag time (time until gravity decreases 3+ points, confirmed via hydrometer, especially at 48 hours) for both batches without making any interventions. Report lag times.
If the direct pitch lags over 48 hours and starter lags under 48 hours, then the starter saved the yeast.

I use 48 hours as a typical acceptable lag time for lagers pitched cold.

I'd really try to get yeast from the same lot. They're made at the same time and have likely been handled/transported under the same conditions. Ritebrew lets you pre-order Wyeast and Omega products for example; I'm fairly sure they'd be the same lot.
Store the yeast yourself until it's as old as you want.
Hypothesis #2: Even a fermentation with an at/past "best by" yeast pack can ferment a challenging brew (50F fermentation temperatures) better than the same wort fermented by a yeast pack within its best buy date used without a starter.
Let's try this:
Hypothesis: Pitching lager yeast at 50°F in high OG wort using a starter produces preferable flavor to directly pitching a non-expired yeast.

You have two experimental variables in your hypothesis, which is a little weird. I would definitely use yeast packs the same age and get two packs from the same lot. See whether only making a starter changes flavor. Use expired yeast for both batches and you can then test both hypotheses with a single experiment since the experimental variable would be the same.

Besides the experimental variable(s), keep as much as possible between the control batch and experimental batch the same.

Make sure wort composition is the same for both batches (e.g. split a batch after the boil and only transfer clear wort to the fermenters). Alternate between fermenters every quart if needed.

Ferment both batches under the same conditions, no matter what happens with lag time. Lag time is expected to be longer with lower cell count!
Base ramping/diacetyl rest on a SG level that you pre-determine.
Package the same and within a reasonably similar timeframe after each batch completes primary and diacetyl rest.

Collecting data
Measure flavor preference based on blind testing, as many participants as you can find.
Triangle tests are good to objectively determine whether people can detect a difference. Provide stats if you do collect triangle test results.
Try to have participants cleanse palates before each sample. It's best if the server is also blinded. If possible, pre-determine the sample ordering to evenly distribute the experimental sample to remove ordering bias (fine-tuning brulosophy's method).
Enter samples into competitions and/or ask a judge (blinded to the experiment) to provide tasting notes or scores.
Because the preference result is highly subjective, the more blinded and unbiased tasting data you can provide, the better.
Since you're trying to present a conclusion, you need to provide meaningful data to support it.

It doesn't need to be super scientific. A minimalistic approach is simply take both kegs to a gathering (don't reveal the experimental variable) and see which one kicks first. This sort of result is still somewhat useful, even though not scientifically rigorous or necessarily conclusive.

Mongoose33's suggestion relates to external validity -- when possible, try to pick a process commonly used so that the results are applicable to as many other brewers as possible.

Hope this helps
 
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