New Wisdom for Yeast Starters

[IslandLizard]

On a slightly off topic note, a dumb question.....

The last beer I used Imperial's Urkel on a Pilsner/Saaz smash. Unfortunately, I underpitched it (info: 4 month old pack into 4 gallons of 1.046 wert, pressure fermented @15psi @ 66F). The beer tastes decent, but there is an off flavor I'm detecting.

Can I use the slurry in a future batch or will that off flavor carry over? Even if I make a new starter from it?

Basically, your previous batch was a large starter... So yes, harvest the yeast cake and reuse some of it in your next batch.

How much to use?
Pitch around 1/3 to 1/2 of the previous yeast cake into a batch of similar size and gravity. Save the rest out for another batch.

With your previous batch you definitely underpitched for a Lager.
http://www.brewunited.com/yeast_calculator.php

 

[IslandLizard]

The beer tastes decent, but there is an off flavor I'm detecting.

Can I use the slurry in a future batch or will that off flavor carry over?

Unless there's an infection or something wrong with the yeast, that flavor should not carry over to the next batch.
Much of all flavor and aroma components are generated during fermentation.

Can you describe the the off-flavor you detect in the previous batch?

Stressed yeast, due to underpitching, lack of oxygen, nutrients, etc. could create odd byproducts. Diacetyl is one of those, but can be converted to alcohol by raising ferm temps toward the end of fermentation. That's your classic diacetyl rest done with most, if not all, Lager fermentations.

 

[dmaxweb]

This past starter I did a 15 minute boil and noticed I lost some volume (250mL). So I did a second step and just boiled for 5 minutes. Now I have a 3L starter of Que Bueno going now for a brew day tomorrow. Que Bueno puts out the rhino farts.

I usually just use dry yeast, but if I use liquid again I'm going to just boil enough to kill off the bugs and not lose volume like @CascadesBrewer or do @day_trippr's method to avoid a messy stove (and the wrath of SWMBO).

What size flask did you use for a 3L starter. I have a 4L Erlemmeyer and brew 11.25 gallon batches. If I brew a lager, there is not enough headspace in the 4L to hit the cell counts in Dads Yeast calculator. I'm looking at adding a 6L erlenmeyer.

 

[IslandLizard]

I have a 4L Erlemmeyer and brew 11.25 gallon batches. If I brew a lager, there is not enough headspace in the 4L to hit the cell counts in Dads Yeast calculator. I'm looking at adding a 6L erlenmeyer.

I find using 2 or 3 smaller, 2 liter flasks more practical for cold crashing. They fit in the kitchen fridge without having to remove shelves. Anything taller and wider becomes a space dilemma in there. But you'd need an equal number of stir plates to go with them.

I have been using (decommissioned) orbital lab shakers for the past 8 years, and can even fit a 3 gallon carboy on them, Or 2 1-gallon jugs, 3 2-liter flasks, or 4 half-gallon pickle jars, etc.

 

[dmaxweb]

I find using 2 or 3 smaller, 2 liter flasks more practical for cold crashing. They fit in the kitchen fridge without having to remove shelves. Anything taller and wider becomes a space dilemma in there. But you'd need an equal number of stir plates to go with them.

I have been using (decommissioned) orbital lab shakers for the past 8 years, and can even fit a 3 gallon carboy on them, Or 2 1-gallon jugs, 3 2-liter flasks, or 4 half-gallon pickle jars, etc.

I tried once using 2 flasks but it was a PITA especially when stepping them up. I have a dedicated refrigerator with the shelves removed that I use for fermenting lagers so space is not a problem. I just need to step up and part with the cash for a 6L.

 

[Northern_Brewer]

People like overkill to make them feel good. If you are really that worried that you can not clean and sanitize a glass flask well enough with StarSan, then what chance is there for any of your other down stream equipment?

The vessel you make your starter in needs to be cleaner than everything else, because it is at an earlier stage in the process and compounding is a [female canine].

Say your contaminant grows like cerevisiae and manages 4 generations in the starter - then 1000 cells of the contaminant at the beginning of your starter is the equivalent of 16,000 cells later in the process. If it can access nutrients that your desired yeast can't - it's diastatic for instance - and manages 8 generations in the starter, then those 1,000 cells are the equivalent of 256,000 cells later on.

So it's worth taking care over any vessel in the early stages, whereas it's far less critical in the later stages.

 

[Yesfan]

Unless there's an infection or something wrong with the yeast, that flavor should not carry over to the next batch.
Much of all flavor and aroma components are generated during fermentation.

Can you describe the the off-flavor you detect in the previous batch?

Stressed yeast, due to underpitching, lack of oxygen, nutrients, etc. could create odd byproducts. Diacetyl is one of those, but can be converted to alcohol by raising ferm temps toward the end of fermentation. That's your classic diacetyl rest done with most, if not all, Lager fermentations.

Kinda "medicine-y", fusal. Almost like rubbing alcohol, but it's at the very end. I'm hoping it's something that fades with time. The beer is a little over 3 weeks old. I pressure fermented that batch in a keg. After 3 weeks at room temp (66F), I put the keg in the fridge, no transfer.

What size flask did you use for a 3L starter. I have a 4L Erlemmeyer and brew 11.25 gallon batches. If I brew a lager, there is not enough headspace in the 4L to hit the cell counts in Dads Yeast calculator. I'm looking at adding a 6L erlenmeyer.

I have a 3L flask. I did a couple of steps to get that (2L, then 1.5L to make up evap loss from the first step). No issue with it overflowing.

Just for clarity, The 3L starter was for today's brew (pitched 3L of Que Bueno in a Mexi-lager). My previous batch is the one that's under pitched. I used just a 3 month old pack of Urkel in it.

 

[IslandLizard]

The last beer I used Imperial's Urkel on a Pilsner/Saaz smash. Unfortunately, I underpitched it (info: 4 month old pack into 4 gallons of 1.046 wert, pressure fermented @15psi @ 66F). The beer tastes decent, but there is an off flavor I'm detecting.

Kinda "medicine-y", fusal. Almost like rubbing alcohol, but it's at the very end.

66F is pretty high for a Lager yeast, fusel alcohol territory, while 15 psi pressure may not alleviate all the side effects of the warmer fermentation.
You're in "uncharted territory," so to speak.
Not every yeast handles temp/pressure the same way either, you just added a data point for this strain.

Did you give it a diacetyl rest for a few days, by removing the pressure, keeping the temps the same?
I've noticed Lagers generally clean up better with it, more than just the diacetyl.

Other possibilities: Underpitching and stressed yeast can cause off-flavors.

I'd keep it cold stored for a few more weeks, it may improve.

 

[Yesfan]

66F is pretty high for a Lager yeast, fusel alcohol territory, while 15 psi pressure may not alleviate all the side effects of the warmer fermentation.
You're in "uncharted territory," so to speak.
Not every yeast handles temp/pressure the same way either, you just added a data point for this strain.

Did you give it a diacetyl rest for a few days, by removing the pressure, keeping the temps the same?
I've noticed Lagers generally clean up better with it, more than just the diacetyl.

Other possibilities: Underpitching and stressed yeast can cause off-flavors.

I'd keep it cold stored for a few more weeks, it may improve.

I didn't do a D-rest. Pretty much I kept it at 15psi/66F the whole way. As fermentation started to wind down, I bumped the spunding valve up to 20psi. When I cold crashed last week, the pressure dropped back to 15psi (fridge temp is 41F). I went ahead and put it on gas and just left it there since. I'm going to let it set for a couple of more weeks like you suggested. I'll take samples here and there.