Fundamental flaw in Wyeast smack pack design?

Got to thinking about this after a discussion with another brewer, maybe I'm off base, maybe not. The theory:

Yeast require oxygen for healthy replication. The smack packs are not gas permeable, thus starting the yeast by bursting the "nutrient pouch" results in less than optimal yeast health, as the cells that survive have been oxygen deprived to a certain extent.

By inflating the smack pack prior to pitching and/or making a starter, do we inadvertantly propagate the less healthy yeast cells? Does this have an effect on the final beer, relative to an "unsmacked" pack?

I'm not convinced one way or another, but would like to get some thoughts.

I don't use Wyeast because I hate those smack packs, but if you're pitching without making a starter it does have an effect on the beer because you're underpitching.

They're not designed to get cells to replicate; it's not like a starter.

It's just a nutrient pack to get them metabolizing and ready to roll. And proof viability.

TyTanium said:

They're not designed to get cells to replicate; it's not like a starter.

It's just a nutrient pack to get them metabolizing and ready to roll. And proof viability.

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+1

It's to give you piece of mind your yeast are alive. It's why alot of brewers (especially new brewers) don't like to use White labs. Because there is no way to ensure viabilty prior to pitching

So ya, you're off base.

And I don't think yest need oxygen to survive

I came here to post what TyTanium just said. Smack packs are not designed to take the place of starters. The lack of oxygen is actually important: yeast should not be in an oxygenated environment unless they are in the growth stage. This will occur once you pitch.

I think they say on their site that they recommend starters as opposed to just smaking, which would solve the o2 problem. The packs are only good in beers up to 1.050 too if i remember right. Not sure if that is to do with just the cell count or if they're accounting for lack of growth in the short period their active after the smack as opposed to being on a stir plate?

Thanks, but I fully understand the importance of starters and pitch rates.

However, by breaking the seal of the smack pack the yeast begin to replicate and give off CO2, which causes the pack to inflate. My question has more to do with this principle:

Is it non-ideal to begin with yeast cell growth that is in a non-oxygenated environment? By "getting them metabolizing and ready to roll", is that not the same as introducing the cells to a sugar source and various nutrients (and thus replication)?

g-star said:

Is it non-ideal to begin with yeast cell growth that is in a non-oxygenated environment? By "getting them metabolizing and ready to roll", is that not the same as introducing the cells to a sugar source and various nutrients (and thus replication)?

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You're not beginning yeast cell growth. Replicate and metabolize are different. That's my understanding at least.

They aren't growing in an anaerobic environment. They are feeding, ie, warming up for your wort. Replication only occurs in the presence of oxygen.

g-star said:

However, by breaking the seal of the smack pack the yeast begin to replicate

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They do not.

g-star said:

Is it non-ideal to begin with yeast cell growth that is in a non-oxygenated environment?

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Yes it is "non-ideal" but they won't "grow" without oxygen.

g-star said:

By "getting them metabolizing and ready to roll", is that not the same as introducing the cells to a sugar source and various nutrients (and thus replication)?

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It depends on what you are using to "getting them metabolizing and ready to roll"

The fundamental flaw is that it's crappy packaging with a gimmick that confuses people. I like some of the Wyeast strains a lot, but hate their packaging.

I actually like the packaging for Wyeast, sure White Labs is a bit more resistant to rough treatment, but I've never had Wyeast froth up and spray everywhere like I do with White Labs vials. I'm not loyal to one or the other, I just use the strain that fits what I'm making, and I never smack my packs, just cut the corner off and pour into my starter.

I think i understand what the OP is getting at but I don't think the concern or perception is really an issue. Even though white lab vials maybe more abuse tolerant, the yeast are still being exposed to the same shipping, storage abuse so assuming viability is less an issue is IMo not correct.

The growth phase requires O2 so without that in a sealed container there is no growth or replication. The fact they provide nutrient is beneficial as the yeast at proper temp will feed and the fact that packs swell is really a factor of temperature and environment and nothing else.

I've used both manufacturers and make starters for all liquid yeast to ensure proper pitch rate and in the end that is what really matters. If there was truly something inherently wrong with one or the other they would not be in business..

duboman said:

I think i understand what the OP is getting at but I don't think the concern or perception is really an issue. Even though white lab vials maybe more abuse tolerant, the yeast are still being exposed to the same shipping, storage abuse so assuming viability is less an issue is IMo not correct.

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I'm having a hard time understanding what was said in that paragraph

duboman said:

The fact they provide nutrient is beneficial as the yeast at proper temp will feed and the fact that packs swell is really a factor of temperature and environment and nothing else.

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The yeast are producing co2 is what makes it swell, no?

O2 itself is not technically required for yeast propagation. Yeast use O2 to make sterols and lipids which are necessary for cell wall growth and fortification, and which are therefore necessary for replication. But New Belgium, among others, have experimented with replacing O2 with small amounts of olive oil (very small amounts) and found they could have effective fermentations with adequate replication that way. That said, they also decided to continue using O2 vs fussing with the olive oil.

When propagated in an aerobic environment, the yeast will be producing and storing lipids and sterols, and therefore can replicate to some degree even once the oxygen is removed, as they have the building blocks stored up for replication. So in a smack pack, no, there's no O2, but the yeast, if healthy in the first place, have plenty of lipids and sterols to allow for the very small (and I do mean very very small) amount of replication that could happen based off of the contents of the nutrient pack.

At least all of that is my recollection as I sit here trying to get the baby to go back to sleep so that I can go back to sleep.

Thanks for all the replies, I'm just trying to understand this from a technical perspective. This seems to be a good explaination:

BrewKnurd said:

When propagated in an aerobic environment, the yeast will be producing and storing lipids and sterols, and therefore can replicate to some degree even once the oxygen is removed, as they have the building blocks stored up for replication. So in a smack pack, no, there's no O2, but the yeast, if healthy in the first place, have plenty of lipids and sterols to allow for the very small (and I do mean very very small) amount of replication that could happen based off of the contents of the nutrient pack.

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I'm not sure there are discrete differences between "metabolizing" and propagating/replicating. The point of the brewer I was discussing this with is that by starting the yeast in the smack pack in an anaerobic environment, you in essence begin to propagate unhealthy cells. However, the above post suggests that this would not be an issue.

Good discussion.

g-star said:

Thanks for all the replies, I'm just trying to understand this from a technical perspective. This seems to be a good explaination:



I'm not sure there are discrete differences between "metabolizing" and propagating/replicating. The point of the brewer I was discussing this with is that by starting the yeast in the smack pack in an anaerobic environment, you in essence begin to propagate unhealthy cells. However, the above post suggests that this would not be an issue.

Good discussion.

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Out of curiosity, have you posed your question to the folks at WYeast? I have found that most science people in the brewing community are very open about discussing and answering questions like these, worth a shot.