New approach to starters

Mark-Farrall

I've really been enjoying the Bru Lab podcast from the Brulosophy guys. One of them has changed his career from law to postgraduate beer study, The Bru Lab podcast is where he walks through various academic beer related research with the researchers.
I'm just about to use one of the episodes on starter preparation. The focus of the paper was on creating conditions to get the yeast to use respiration instead of fermentation. Respiration is much more efficient at generating the ATP that yeast use to store energy for growth and fermentation (I think it was about eight times more efficient). Yeast will prefer to use fermentation if there's enough sugar present, so the starter needs to have a very low level of sugar and a relatively high level of nitrogen to prompt the yeast to start using respiration.
The study with the very sexy name of 'Effect of the respiro-fermentative balance during yeast propagation on fermentation and wort attenuation' saw more cells produced in the starter and a more efficient fermentation in the final beer. The paper is here - https://onlinelibrary.wiley.com/doi/full/10.1002/jib.621 and the podcast is here - http://thebrulab.libsyn.com/episode...en-on-yeast-propagation-w-dr-maria-moutsoglou
For the starter I'm trying it's going to be a starting gravity of 1.008 and 2.5 grams per litre of yeast nutrient to provide the nitrogen. It's going to be a couple of steps before I pitch it into the full strength beer so it will be a little later until I come back with how well it works, or doesn't work.
Anybody else played around with this approach?

Minbari

Nope have always made starters @ 1.040.  interested to see your results

HighVoltageMan!

This is kind of the approach that makes yeast propagator work. It keeps the yeast in an aerobic state with a constant source of oxygen, the yeast will produce biomass and very little alcohol or carbon dioxide. As it grows yeast, they add wort to "feed" the propagator. I think it needs a lot of FAN, but I believe most malt has enough.
Sounds pretty cool, I'll give the podcast a listen.

Mark-Farrall

So I listened to this on the drive home tonight and my takeaway was lower OG wort with more nutrient...interesting there was no mention of oxygenation which is also a yeast need and with  nitrogen being the most prevalent gas in our environment, no mention of aeration!
Never the less, Bru Lab is a really good deep dive into the hard science of what is really going on in that part of the brewery that most folks don't even know exists!  When I listen to some of these podcasts, I feel like the casters are guessing at what professionals are doing to get their beer to taste the way it does! Cade gets those guys and gals on the podcast with him and the talk it through!  It's amazing what beer science has contributed to chemistry and biology!  The  pH  story alone is mind blowing!

HighVoltageMan!

For the oxygenation they were using a stir plate during the experiment, so it would haven been constantly oxygenated. I don't have a stir plate so I'll just be using the shake it whenever I go past it method.

Mark-Farrall

Ah!  The 007 Method....Shaken..not stirred!

Donoroto

I listened to the podcast and I gave the paper a quick look over. I want to give this method a try, but the devil is in the details. Specific amounts of carbon is easy to measure. It looks like the gravity needs to be @ 3 Plato to get 2 Plato of useable carbon (in the form of sugar), so no problem there, but the amount of nitrogen in the form of FAN seems to be a little harder to gauge. A standard recipe with commonly available ingredients needs to be defined.
The other thing is oxygen. It looks like they may have used pure oxygen at first and then they must have use a stir plate with no additional oxygen after the first dose. I'm I understanding that correctly? What about a air pump with a HEPA filter constantly introducing air/oxygen into the flask?
The other question I have. Does a liter of 2-3 Plato starter with a higher FAN (the 100 ratio vs 800) grow 40% more yeast than a 1 liter 9 Plato wort with no additional FAN? If this is true, this is really cool! You can use 1/3 the gravity and grow more yeast. Way less DME or wort.
Yeast propagators have been around since Emil Christian Hansen developed one @ 1890 or so. He was able to get the yeast to reproduce aerobically. It's way more efficient since very little alcohol and cO2 are produce. all the nutrients go into biomass. These are used in breweries and in yeast labs, but they are very expensive and require some technical expertise to get to work correctly.
If it could be done on a homebrew level, it would so cool. Not only are the yeast heathier, there are more of them.
Thanks again Mark for bringing this to the forum!

HighVoltageMan!

In the discussion part of later episodes Cade speculates on using yeast nutrient to get the nitrogen levels up while keeping the DME levels low. The 2.5 g/litre of yeast nutrient is an untested estimate from him.
I'm trying to revive some 5 month old slurry of a mixed ferment Saison. I suppose I should build up two starters, one with the low carbon high nitrogen approach and the other with the only DME at 100 g/litre approach. It will be a very rough test as I'll just be grabbing a roughly similar amount of slurry and putting it into 200 mL initial starters. Then step up to 1 litre. Which should be enough if I'm splitting my usual 12 litre batch size into two containers. Especially if I do my 3.5 % ABV Saison as I was intending. Though I could do my standard 6% ABV version instead.

Trialben

I'd like to hear how they compare.

Mark-Farrall

This is one of those discussions that reminds me that I am such a newbie to all of this.  Will be interesting to hear what the results are if anyone plays around with it.  Guess I need to add to my reading list.

Trialben

This is my question about nutrient. The experiments were done with a yeast derived nutrient, which contains FAN (free amino nitrogen). These are readily available amino acids that the yeast can use to build biomass.
The other nutrient mentioned id DAP (diammonium phosphate). They didn't do any work with this as a source of nitrogen, but it's relatively cheap and is @ 18% nitrogen by weight. It would be the easiest to use, measure and predict the carbon to nitrogen ratio. It's used with making meads, wine and seltzers as a yeast nutrient, so it's may work just fine with this method.
I looked into yeast extract, but I was unable to get a spec on the amount of FAN% by weight. White Labs has a product called FANMax Bio. It's also sold by the ounce, 2Kg and 6Kg. If you could get some FAN numbers with this product it might be the ticket to get this work like the original experiment.
I also looked into an aquarium pump with a HEPA filter. I was thinking that if the air was pumped into the wort directly it would be an excellent source of oxygen and it wouldn't need to be stirred since the agitation from the air would act as a stir bar.
Time to crawl back into the old rabbit hole, wish me luck!

Hawkbox

I havnt listened to the podcast will do thanks for the link Mark.
I had a read if the paper last night and I  had a really good sleep lol!
This was my question how are you going about creating this low C:N ratio wort medium.
Are you going to use a low Plato wort and use yeast Nutrient to provide the FAN ?
How are you going to compare the starters Mark?
I did see 100g/l DME starter as one for reviving your 5 month old Saison.
The other one what low OG wort with nutrient?
I Use RWS for every batch of beer I brew.
My thinking what better for propagating the yeast and preparing them for fermentation than the actual wort?
I've been adding yeast nutrient to these as a bit of a health perk for the yeast.

Trialben

I was going to try the yeast nutrient for the nitrogen, based on Cade's recommendation. It is pretty obvious that nobody is publishing data on how much FAN is in those yeast nutrients, so it is a bit of a guess. Depending on what high voltage man finds I might pop into the LHBS on Monday to get some DAP. I've been planning to get some for a while, mainly to add to the slurry that I store.
I don't see I have a method of comparing the starters until I put them into the final beer. I was expecting to compare the fermentation profile mainly, using a tilt in both fermenters. I'll try a triangle test on the finished beer, but I suspect it may not be noticeable. I'm certainly not going to get into the level of cell counting that would be needed to confirm this.
I was just going to use my normal approach for reviving the old slurry which is 100 g/litre DME starter for 2-3 days. Crash it and then use that on the finished beer. I do use the approach you're suggesting if it's under two months in the fridge, but this batch is older than that. So wanted to stick to the normal process as much as possible.