Rehydrating yeast

[eadavis80]

To the OP - next time brew a split batch - pitch some with rehydrated X yeast and some with sprinkling it on top and then you can decide for yourself if you see a difference. In all honesty, I think there are a lot of other factors that influence the quality of a beer more so than whether or not the yeast is rehydrated.

 

[Rob2010SS]

Reloads with "hot"+P rated kitty food.
Seriously, though, one of my friends was using +P without changing his compact .45 recoil spring. The ejected casings came straight back, one with enough force to cut the bridge of my nose when it hit my face.
Fun times.

Regardless of method, may your brews turn out well and always take the advice of Beer Gods with a grain of brewing salts.

Ha, this is pretty funny Lefou. I have a .50 Cal desert eagle that if you're holding it just right, the cases come straight back and hit you square in the forehead. I've come home numerous time from the range with what looks like the bottom of a smiley face on my forehead, LOL.

Thanks guys for all of the info. Never meant for this thread to turn into a battle but it's helpful to hear all of the feedback. Hearing and now understanding how rehydrating is done and WHY it's done, I'm less intimidated to try it and see how it goes.

 

[ncbrewer]

A concern I have with dry pitching is the temperature. Fermentis offers the alternative of pitching dry yeast onto the wort, but the wort should be above 68F. I prefer to pitch cooler than that.

 

[dyqik]

A concern I have with dry pitching is the temperature. Fermentis offers the alternative of pitching dry yeast onto the wort, but the wort should be above 68F. I prefer to pitch cooler than that.

I suspect that's most likely why they offer the tip of rehydrating first in a smaller volume of water or wort. You want the yeast to rehydrate warm, then carry out the majority of the growth phase at significantly lower temperatures. That's very hard to do without a cooling loop and heat exchanger in your fermentor.

 

[beernutz]

That escalated quickly.

 

[RPh_Guy]

People on Team Rehydrate always like to quote statistics and try to explain the science.

I'm on Team Dry-Pitch for 2 reasons:

1) there is no scientific evidence to suggest that rehydrating yeast creates a better tasting beer (prove me wrong). All the taste tests I've found posted on the Web have found no reliable difference.

2) rehydrating incorrectly or for too long a period can have as many theoretical disadvantages as dry pitching. Sources of contamination, temperature shock, and/or oxygen depletion, to name a few.

And ahem, it is well described that yeast growth is logarithmic, following first order kinetics. During the growth phase the yeast will double every 1-2 hours (or whatever) regardless of how much you pitch. We already take adequate measures to avoid stress during this phase -- oxygenation and temperature control, which should overcome any marginal variance from what we deem to be normal pitching rates, as people have already alluded.

To further complicate matters, we may not even really know how many cells are in the dry yeast packets. Some attempts to determine the validity of the yeast manufacturers' claims have found drastically higher cell counts that indicated.

One more thing, where is the study that suggests there is such a proportionally large decrease in viability when rehydrating in wort as opposed to water? I hope it's not some made-up statistic that has been repeated enough times to be considered fact. Is the proposed decrease in viability honestly due to the components of the wort as everyone seems to think or is it more related to the initial temperature at hydration?

While it is a life or death situation (for the yeast) either way can make good beer.
Meow!

 

[h22lude]

People on Team Rehydrate always like to quote statistics and try to explain the science.

I'm on Team Dry-Pitch for 2 reasons:

1) there is no scientific evidence to suggest that rehydrating yeast creates a better tasting beer (prove me wrong). All the taste tests I've found posted on the Web have found no reliable difference.

2) rehydrating incorrectly or for too long a period can have as many theoretical disadvantages as dry pitching. Sources of contamination, temperature shock, and/or oxygen depletion, to name a few.

And ahem, it is well described that yeast growth is logarithmic, following first order kinetics. During the growth phase the yeast will double every 1-2 hours (or whatever) regardless of how much you pitch. We already take adequate measures to avoid stress during this phase -- oxygenation and temperature control, which should overcome any marginal variance from what we deem to be normal pitching rates, as people have already alluded.

To further complicate matters, we may not even really know how many cells are in the dry yeast packets. Some attempts to determine the validity of the yeast manufacturers' claims have found drastically higher cell counts that indicated.

One more thing, where is the study that suggests there is such a proportionally large decrease in viability when rehydrating in wort as opposed to water? I hope it's not some made-up statistic that has been repeated enough times to be considered fact. Is the proposed decrease in viability honestly due to the components of the wort as everyone seems to think or is it more related to the initial temperature at hydration?

While it is a life or death situation (for the yeast) either way can make good beer.
Meow!

I'm all for people pitching directly into wort especially with a lower og beer (1.060). What I don't get is why people are fighting the fact that sugar kills yeast. This isn't just a beer thing. Sugar can damage yeast cells and kill the yeast. It won't damage all the cells but it will damage some. If you pitch directly into wort, some cells will die. Please don't read that as direct pitching won't make good beer. I never once said that. All I'm saying is, it is a FACT that sugar can damage some cells which lowers the healthy cell count.

The reason direct pitching still makes good beer is because there are a lot more cells in the packet than the beer actually needs so some damaged cells are ok.

The reason rehydrating is suggested is because dry yeast cell walls can't filter out what is bad for the cells. That's why direct pitching damages some yeast. Rehydrating in sterile water will strengthen the walls which then allows them to filter out the bad (i.e. sugar) so the cells won't get damaged.

Direct pitching is fine as there are enough cells but for me I'd rather not chance it.

 

[shanecb]

I'm all for people pitching directly into wort especially with a lower og beer (1.060). What I don't get is why people are fighting the fact that sugar kills yeast. This isn't just a beer thing. Sugar can damage yeast cells and kill the yeast. It won't damage all the cells but it will damage some. If you pitch directly into wort, some cells will die. Please don't read that as direct pitching won't make good beer. I never once said that. All I'm saying is, it is a FACT that sugar can damage some cells which lowers the healthy cell count.

The reason direct pitching still makes good beer is because there are a lot more cells in the packet than the beer actually needs so some damaged cells are ok.

The reason rehydrating is suggested is because dry yeast cell walls can't filter out what is bad for the cells. That's why direct pitching damages some yeast. Rehydrating in sterile water will strengthen the walls which then allows them to filter out the bad (i.e. sugar) so the cells won't get damaged.

Direct pitching is fine as there are enough cells but for me I'd rather not chance it.

This 100%. If I only actually need 50-60% of the cells that would be in a packet of yeast, then I'd dry-pitch. But if I need the full cell count (which I most always do), then I rehydrate. In both cases, they still make good beer, it just depends fully on what you need out of the yeast.