First time starter question

[half_whit]

I've always been the more of the RDWHAHB brewer. I've always used single vial WL yeast and I've always (with one unrelated exception) ended up with a drinkable beer. I decided to pay a little more attention to my yeast count starting with this next brew as it has an OG of 1.07. "He who increases knowledge increases sorrow..."

I purchased the canned wort from Midwest to save me a step and ordered a stir plate. Problem is my stir plate wont arrive until after brewday, so I will be using the shaking method on this one.

All of the online yeast starter calculators say I'll still fall short by 1/3rd of the recommended count, even with a 2L starter (200b cells vs 290b recommended)

So my question is this: do I delay my brew by a week so I can do a multi-step starter? Or am I worrying too much about a situation where I once never bothered to worry at all?

 

[RPh_Guy]

I'd go ahead without the stir plate.

 

[WBB]

No and yes.

 

[Jag75]

Do a shaken not stirred starter . Works great .

 

[Jmspears]

I don’t have a stir plate. Never had a problem with the shaking method

 

[isomerization]

Anyone read this article?

https://pdfs.semanticscholar.org/e5e8/ea0b5a6e5bc0d41a3cec881e26a84d0e4d6c.pdf

Figure 1 suggest much lower yields without constant agitation, but they only went 1-2 days. I wonder what the results would be if extended to 4 days?

 

[RPh_Guy]

Continuous aeration is well known to produce higher cell counts.

 

[isomerization]

Continuous aeration is well known to produce higher cell counts.

That figure is not using continuous aeration.

 

[half_whit]

Update, made the starter before dinner yesterday. SWMBO and I pick it up and swirl it up every time we walk past it

 

[Boleslaus]

1.07 isn't huge so things should turn out fine for you. I don't have a stir plate and I only do 2 stage starters with beers over 1.08. Maybe my beers could be improved in this regard, but I haven't had anything to complain about.

 

[RPh_Guy]

That figure is not using continuous aeration.

Yes it is. A stir plate provides continuous areation, that's the point of using it.

Comparison of the number of yeast cells in starters which were mildly aerated (shaken intermittently), moderately aerated (injected with air intermittently) or highly aerated (continuously stirred) suggest that an increase in aeration/agitation does correlate with an increase in yeast cell number (Figure 1).

It wouldn't matter if they had tested cell counts later. The growth phase occurs at the beginning, before the bulk of fermentation.

 

[isomerization]

Yes it is. A stir plate provides continuous areation, that's the point of using it.



It wouldn't matter if they had tested cell counts later. The growth phase occurs at the beginning, before the bulk of fermentation.

Fair enough, I was thinking you were referring to continuous oxygenation, so my bad.

On the second part, how do you know that the yeast was through the growth phase? They didn’t provide kinetic data, so perhaps lag phase was extended in the unstirred cultures?

 

[RPh_Guy]

how do you know that the yeast was through the growth phase? They didn’t provide kinetic data, so perhaps lag phase was extended in the unstirred cultures?

Call it an educated guess.

They used 10mL of concentrated slurry in 500mL wort. Assuming 5 B/mL for the "concentrated" slurry and 1.040 sg, that's an enormous 10M/mL/°P pitch rate -- a full order of magnitude higher than a standard pitch rate. Such a huge pitch and 75°F fermentation will produce very short lag and growth phases even with inadequate aeration.
Just read the rest of that article you linked; they explain the yeast life cycle and timeframe in detail.

Also, these results match other scientific experiments.

 

[isomerization]

Call it an educated guess.

They used 10mL of concentrated slurry in 500mL wort. Assuming 5 B/mL for the "concentrated" slurry and 1.040 sg, that's an enormous 10M/mL/°P pitch rate -- a full order of magnitude higher than a standard pitch rate. Such a huge pitch and 75°F fermentation will produce very short lag and growth phases even with inadequate aeration.
Just read the rest of that article you linked; they explain the yeast life cycle and timeframe in detail.

Also, these results match other scientific experiments.

Do you think this relationship holds up regardless of pitch rate?

Since the lag phase was severely decreased, what would happen with the different aeration techniques with pitch rates more appropriate for homebrewers?

 

[RPh_Guy]

Do you think this relationship holds up regardless of pitch rate?

The relationship that increased oxygen increases the cell count? Yes, unless maybe if you pitch so much that there's no growth at all.

Since the lag phase was severely decreased, what would happen with the different aeration techniques with pitch rates more appropriate for homebrewers?

The pitch rate used in the experiment was appropriate for measuring the effect of aeration technique on starters, and applicable to homebrewers. Most yeast packs probably have around 50 billion viable cells when pitched into a starter.

Too much areation in a batch has detrimental effects (i.e. oxidation), so we don't want to continuously aerate the full batch.