Don't Rehydrate Dry, and Don't Aerate Liquid Yeast?

[WiscBrewer]

Has this video been discussed here? Thoughts?

 

[North_of_60]

Interesting! The lazy part of me likes this. I have only used dry yeast. I have rehydrated some batches and have pitched some straight into the fermenter. I have sprinkled several batches on top and sealed the bucket, others I have stirred well after pitching.

I have shaken the bucket vigorously to aerate it and I have not aerated at all other than the splashing that occurs when I transfer from boil to fermenter.

I have not noticed any difference in lag time, fermentation time, hitting my FG, or taste. Usually I pitch the yeast in the late afternoon or evening and by morning the airlock is busy. The only exception is the slurry I just pitched. It took off in less than 3 hours.

 

[mabrungard]

The debate about dry yeast rehydration has been ongoing for a while. There are some dry yeast manufacturers that don't advocate rehydration and others that do. I'm curious if this is another manufacturer going to no rehydration or the same cast of characters? I'd be interested in seeing the supporting research that points to no rehydration. I have seen several research journal articles that do confirm that rehydration in a properly mineralized water is better than no hydration in terms of overall vitality.

The finding on no aeration for liquid yeast is a surprise. As with all things internet: I do require the citation from the research study that produced that recommendation. I disagree with the premise that yeast get an energy boost from aeration. Oxygen is used by yeast to build sterol reserves in the cell walls so that they can undergo more cell divisions and reach desirable cell counts during the fermentation. It is not an energy boost that stimulates activity.

I look forward to further discussion on these issues.

 

[Reavers2013]

I am careful about using dry yeast (I feel the drying process harms the yeast and is more likely to create off flavors) so I won't comment on that.

However, for oxygen st the start of fermentation I know you can add to much oxygen if using pure oxygen but I fix this by using an aquarium pump for 5 minutes and with the low oxygen concentration in air it is almost impossible to add to much oxygen. Since switching to this from just shaking a stirring I've noticed two things. 1) fermentations starts in about half the time it used to and 2) my beers have much less off flavors.

The flavor may be a correlation and not a causation with having more batches under my belt but the thought of yeast needing oxygen to create more cells during the growth phase checks out so if it isn't broken don't fix it.

 

[brew703]

I've been using dry yeast lately, mainly S04 and US05. This past Friday I brewed a Saison using BE134. I have been re-hydrating all yeast. The BE134 yeast took off at 6 hrs (70 degree temp) and was a beast through the weekend. Yesterday evening it started slowing down. This morning still have airlock activity but no where near as often as Saturday and Sunday morning.
The S04 and US05 normally takes 24-30 hrs to get going. Next time i brew and use one of these I will just sprinkle on top of the wort and see what happens. I haven't noticed any off flavors.
I also use pure oxygen for 45-60 seconds using the stainless oxygen stone from Williams Brewing. It's worked great so far (2+ years) and never had an issue.
TBH not sure if rehydrating or using oxygen really helps all that much.

 

[The_Bishop]

I have a hard time taking that video at face value. Those are some topics with a lot of research behind them, and whats being claimed in that video is almost diametrically opposed to that research with no validating data or citations given. Also, some of the data spoken of is incorrect, as Martin points out: The oxygen is used to build sterol reserves, not as an 'energy boost'.

 

[Smellyglove]

I'm sticking to my own (although limited experiences) with one strain of dry yeast.

I've made one beer several times, to sort of investigate this. Same maltster, same grist, same mashing regime, same OG, and of course same yeast from the same batch, etc.

It's a beer where I want phenols. You get more esters/phenols if you underpitch, right?

The two times I hydrated the yeast, the phenols were completely different, the ones where I rehydrated was "boring", the ones where I didn't rehydrate had the phenols I'm after. My interpretation of this is what is already known/at least that's the reason to hydrate afaik, you kill yeast by not rehydrating it first, thus a smaller pitch.

 

[beernutz]

I don't think David Heath was advising brewers to stop rehydrating yeast and aerating wort but was instead reporting what he'd heard at an industry symposium about one yeast manufacturer's experimentation and their upcoming change in yeast use instructions on their packaging. I believe in the video he said he doesn't rehydrate dry yeast anyway but he always aerates his wort and will continue to do so.

It wasn't crystal clear in the video but it appeared that both experiments were done by the same yeast manufacturer.

I have to wonder if their aeration experiment results were for dry or liquid yeast or both. I am also really curious which of the two big dry yeast manufacturers did the experiments: Lallamand or Fermentis (SafAle and SafLager), as I'm assuming its one of them. Both still recommend rehydration, Lallemand emphatically so.

http://www.lallemandbrewing.com/products/brewing-yeast/

 

[Setsumi]

One reason I rehydrate dry yeast it helps that the krausen ring washes off easier.

 

[corax]

I suspect that the media in which they are dried has a huge impact on the rehydration viability of dried yeast, and I also suspect that different manufacturers use different media. And I'm confident that the manufacturer is in the best position to know the best practices regarding rehydration of their own yeast.

In other words, your best bet is to follow the manufacturer's instructions for your yeast of choice.

 

[ESBrewer]

'Yeast health' as defined by humans is very subjective and can be a bit misleading as nobody knows what he means with it. Brewers are more interested in beer taste and I think we know that aeration affects the outcome. Sometimes it is good and sometimes it is bad. It has been long known that high amounts of oxygen can be toxic to yeast and humans as well. And yet oxygen is so vital for us. So it is probably not that black and white.

 

[mediant]

I believe this is where the "don't rehydrate" part stems from - https://fermentis.com/news-from-fermentis/technical-reviews/e2u-direct-pitching/

 

[MSK_Chess]

My understanding is that liquid yeast does need aeration (oxygen) whereas dry yeast during its aerobic production stage accumulates enough fatty acids and sterols to produce enough biomass during the primary stage of fermentation

 

[homebrewer_99]

Even after whirlpooling (after chilling) I let the wort sit for 5 minutes (to allow the hops and break accumulate in the center) before racking to the boil pot. I also strain the wort (which aerates it) through a nylon net to capture anything that drains from the pot.

I'm assuming some will try this new info while others will continue doing as they've always done...IF IT AIN'T BROKE, DON'T FIX IT.

 

[brewgar]

I believe this is where the "don't rehydrate" part stems from - https://fermentis.com/news-from-fermentis/technical-reviews/e2u-direct-pitching/

Thank you, MEDIANT, for your post. Nothing like getting facts from the source.