A starter revolution?

[Finn Berger]

The brülosophers have done a rather stunning exbeeriment on starters. Lower starter gravity to 1.008 to get rid of the Crabtree effect, and you'll be getting a lot more cells for you sugar - and not only that, you get yeast that do a better job. https://brulosophy.com/2022/10/24/exbeeriment-impact-yeast-starter-strength-has-on-a-munich-helles/

Here's the study it is based on: https://onlinelibrary.wiley.com/doi/full/10.1002/jib.621

What seems important is using both enough yeast nutrient, and using the right kind. That means yeast extract based, not diammonium sulfate.

 

[MaxStout]

Interesting.

Based on my back-of-the-envelope math, since DME contains ~10% glucose, that means no more than 20g/L, rather than the typical 100g/L. So, 1.008 vs. 1.040 wort. The math checks out. The tasters in the exbeeriment didn't show a statistically significant difference in taste perception, so if drinkers can't perceive the difference, why use all that DME?

I've been brewing with dry yeast the past few years, but next time I use liquid, I might try that. I have an upcoming Dubbel that I plan to pitch WY3787, so I'll have the chance to test drive the method.

 

[GigaFemto]

The study talks about a wort with 2 Plato of FERMENTABLE sugars, not an OG of 2 Plato. Their tables show that the worts with 2 Plato of fermentable sugars had OGs from 3.1-3.3. Still quite low, but not as low as 1.008. Their results negate the common statement that "a starter is just a small batch of beer". A starter is better considered to be a yeast growth culture, and this study shows that maximizing yeast growth requires different conditions than making beer.

--GF

 

[Finn Berger]

The study talks about a wort with 2 Plato of FERMENTABLE sugars, not an OG of 2 Plato. Their tables show that the worts with 2 Plato of fermentable sugars had OGs from 3.1-3.3. Still quite low, but not as low as 1.008. Their results negate the common statement that "a starter is just a small batch of beer". A starter is better considered to be a yeast growth culture, and this study shows that maximizing yeast growth requires different conditions than making beer.

--GF

I just went by what Cade Jobe wrote in the exbeeriment report: "Through discussion with Dr. Maria Moutsoglou on episode 062 of The Brü Lab, I learned that yeast seem to benefit from propagation in lower strength starters around 1.008 OG." He may have misunderstood her. Still that seems to have worked.

The study report is just a bit too technical for me, I'm afraid, when it gets to the details. I have no background in the "real" sciences. I'm a retired history/litterature/philosophy teacher, and as a brewer I bitterly regret my lack of better knowledge of physics, chemistry and biology. I just know the philosophical basis for them

 

[GigaFemto]

The final sentence of the original research article is:
"This work suggests yeast propagated in wort supplemented with yeast extract to a 100 C:N ratio and diluted to 2°P of fermentable sugars yields high quality fermentations and promotes complete wort attenuation."
There are two parts, with the main one being to provide enough nitrogen to have a 100 C:N ratio. In that case the amount of sugar is not so important and very low concentrations can be used. Looking at their Table 1, the wort with 2P of fermentable sugars, or 3.3 P OG, had 0.2 g/liter (200 ppm) of FAN to achieve the 100 C:N ration. Higher gravity worts need correspondingly high FAN numbers. Looking at the spec sheet for White Labs FANMax Bio (https://whitelabs.com/public/uploads/ckeditor/5ff8ce61bd9fa1610141281.pdf) the normal recommended concentration for yeast propagation is 50-75 g/barrel, where 100 g/barrel produces 30 ppm of FAN. In other words, the normal dose would be 15-22 ppm of FAN, so dosing to 200 ppm would be 9-13 times higher. 200 ppm FAN would be 667 g/barrel, or 5.7 g/liter. The yeast nutrient is sold in 28 gram packages, so you would get 5 starters from each $12 package, or $2.43 per starter. That seems pretty pricey, although the cost would be offset a bit by the savings in DME. I am also concerned that the other ingredients in the yeast nutrient could be problematic at these very high doses.

The Brulosophy exBEERiment did not state which yeast nutrient was used or how much was used; it just said the same amount was used for both strengths of wort.

--GF

 

[Finn Berger]

The final sentence of the original research article is:
"This work suggests yeast propagated in wort supplemented with yeast extract to a 100 C:N ratio and diluted to 2°P of fermentable sugars yields high quality fermentations and promotes complete wort attenuation."
There are two parts, with the main one being to provide enough nitrogen to have a 100 C:N ratio. In that case the amount of sugar is not so important and very low concentrations can be used. Looking at their Table 1, the wort with 2P of fermentable sugars, or 3.3 P OG, had 0.2 g/liter (200 ppm) of FAN to achieve the 100 C:N ration. Higher gravity worts need correspondingly high FAN numbers. Looking at the spec sheet for White Labs FANMax Bio (https://whitelabs.com/public/uploads/ckeditor/5ff8ce61bd9fa1610141281.pdf) the normal recommended concentration for yeast propagation is 50-75 g/barrel, where 100 g/barrel produces 30 ppm of FAN. In other words, the normal dose would be 15-22 ppm of FAN, so dosing to 200 ppm would be 9-13 times higher. 200 ppm FAN would be 667 g/barrel, or 5.7 g/liter. The yeast nutrient is sold in 28 gram packages, so you would get 5 starters from each $12 package, or $2.43 per starter. That seems pretty pricey, although the cost would be offset a bit by the savings in DME. I am also concerned that the other ingredients in the yeast nutrient could be problematic at these very high doses.

The Brulosophy exBEERiment did not state which yeast nutrient was used or how much was used; it just said the same amount was used for both strengths of wort.

--GF

Yeah, I've been developing the same concerns. I did a starter yesterday with Servomyces, using 2,5 gr for 3 litres of 1.013. That probably is too extreme. It's 10 times what I would use for a normal 25 litres (6+ gallons) batch.

Anyway, it means the yeast is getting a heavy dose of zinc, which can't be healthy - though the starter tasted fine this morning, when it obviously was finished (1.002). (Palmer says too much zinc will cause off-flavors, and it hasn't done that.)

An other problem is susceptibility to infections. When respiring, the yeast doesn't produce alcohol - I tasted nothing, it was extremely bland - and all that nitrogen is food for microbes, too. So you need to be even more extreme with your hygiene measures than normally - if possible.

Before all this came up, I had ordered 1 kg - 2 pounds - of Fermaid O, which seems to me to be rather perfect for this. A bit cheaper, so maybe the cost won't be prohibitive. (I normally spend very little on my starters, as I use wort decanted from what's left in the kettle after I've transferred the wort to the fermentor. I stop the transfer when the wort coming gets unclear. To back up that I'm making a batch of starter wort from time to time, keeping it in my freezer.)