Does rousing yeast really work?

[TAK]

I know people on HBT say it does, but I have some skepticism. It seems to me that when the yeast flocculates, it's made it's decision. Every time I rouse the yeast cake, it settles back down in no time. It's not as though when you get the yeast back into suspension they're like "oh ya, I totally forgot how awesome it is up here. I think I'll hang out."

Of those who say "yes, this works for me," has anyone tested to verify the results? I'd be interested to see the same wort, the same yeast, the same pitch rate, one carboy roused, the other not, and the FG results of each.

 

[Billy-Klubb]

it does work... to a point. if you have a beer that stalled at say 1.034 for 3 weeks (which I did), and roused the yeast for a day or two (which I did), chances are that the yeasty beasties are gonna get back to work. you can also help wake them back up with a small sugar addition. now before you go nay-saying all like, "but the yeast will just eat the new sugar..."-- you'd be right in that assumption. but if it's at 1.034 and you add 1.004 or so in new sugar and they take it down to 1.012, they ate the old & new.

 

[TAK]

How about just helping a flocculent strain along? I ask at this particular moment because I have a barley wine 5 days in with WLP007.

It's flocculating now, but still eating a bit. Refractometer suggests that im probably down to 1.025-1.030. Who knows though, my post fernentation WCF flys all over the place batch to batch.

If it's eating, am I throwing snake oil at it if I think rousing daily is helping it get the best possible FG? Just seems silly when it settles back down into a cake hours later.

 

[Hex23]

I've dropped another 4 points with Wy1968, a highly flocculent strain by rousing. But you should also consider warming as well assuming you have some room to do so (e.g you're not already at 75 or 80F)

 

[TAK]

I've dropped another 4 points with Wy1968, a highly flocculent strain by rousing. But you should also consider warming as well assuming you have some room to do so (e.g you're not already at 75 or 80F)

I did warm it a bit, but not that assertively. I started at 64*F and at signs of slowing, I let it rise to 68-69*F.

 

[duboman]

IMO, you should stop using a refractometer for your FG readings and use a hydrometer. Once alcohol is present refractometer readings, even with proper conversion calculations, are less than accurate and may explain why your FG readings are typically all over the place You may also find that all these readings you think are high or stuck are in fact truly lower and the beers have been done fermenting.

To answer the question, yes, with certain strains rousing and raising temp do help a lot, especially strains that are highly flocculant with less than ideal temperature control.

 

[billl]

I think you need to clarify what you mean by "rousing".

If you are talking about just swirling the cake for an actively fermenting brew, I'd say you are probably right. The yeast are doing their thing whether you intervene or not. Whatever small percentage stays in suspension is dwarfed by the great mass of yeast already working there.

If you are talking about a fermentation that is petering out or stalled completely, I think the odds change a bit. Sure, 99% of the yeast might settle back out quickly, but that 1% that don't is a meaningful quantity compared to the near 0% that were working before.

 

[tooldudetool]

+1 duboman,
I don't use a refractometer but it has always been my understanding that they are only accurate for unfermented wort.

 

[Matt3989]

Not to change the subject too much, but a refractometer will still work after alcohol is present, it's not going to vary wildly and unpredictably. You can actually make a very accurate mathematical correction for alcohol content ( way more accurate than the scale on a refractometer allows for anyway)

http://www.musther.net/vinocalc.html#monitorferment

Here's a link to am online calc.

 

[duboman]

Not to change the subject too much, but a refractometer will still work after alcohol is present, it's not going to vary wildly and unpredictably. You can actually make a very accurate mathematical correction for alcohol content ( way more accurate than the scale on a refractometer allows for anyway)

http://www.musther.net/vinocalc.html#monitorferment

Here's a link to am online calc.

While I will not argue the accuracy of this calculator it is mine and many others experience that even with accurate calculators they can still be off depending on the brand and model of refractometer being used. I suggest a hydrometer as my instrument of choice when verifying FG, takes any guess work out of verification. Based on the gravities the OP is listing as being high I am leaning towards the use of refractometer for readings and if the OP uses a hydrometer he will be pleasantly surprised at the findings

 

[philosofool]

IMO, you should stop using a refractometer for your FG readings and use a hydrometer. Once alcohol is present refractometer readings, even with proper conversion calculations, are less than accurate and may explain why your FG readings are typically all over the place

A refractometer is precise, but not accurate. Successive measurements of the same beer at the same stage of fermentation will yield the same result. This means that you can use it to see if your beer is still fermenting, but cannot calculate the FG from the refractometer reading. However, if the calculators are saying that your are near your target FG and you are seeing no signs of fermentation, you cab be pretty confident that it is terminal. Once you reach that point, you can take a hydrometer reading if you want to know the FG.

 

[duboman]

A refractometer is precise, but not accurate. Successive measurements of the same beer at the same stage of fermentation will yield the same result. This means that you can use it to see if your beer is still fermenting, but cannot calculate the FG from the refractometer reading. However, if the calculators are saying that your are near your target FG and you are seeing no signs of fermentation, you cab be pretty confident that it is terminal. Once you reach that point, you can take a hydrometer reading if you want to know the FG.

I agree but when someone posts that their fermentation is stuck and the readings don't change and their reading is higher than expected its important to point this fact out, which I did

 

[TAK]

I completely agree. For the record, although I did mention FG, I did not imply that I'm using my refractometer for my FG reading. Since I've been opening the carboy to swirl the cake with a sanitized racking cane, which is what I mean be "rouse" in this case, I've been taking small samples for gravity readings. When I eventually rack, which I won't bother for at least 4-5 weeks from pitch, I'll pull a large enough sample for a hydrometer reading and my FG.

I'll also take a refractometer reading from my hydrometer sample. I compare that to the FG from hydrometer to keep WCF stats.

Matt3989, I'm not at my computer at the moment, but thanks for the link. I'll check it out.

 

[Billy-Klubb]

I completely agree. For the record, although I did mention FG, I did not imply that I'm using my refractometer for my FG reading. Since I've been opening the carboy to swirl the cake with a sanitized racking cane, which is what I mean be "rouse" in this case, I've been taking small samples for gravity readings. When I eventually rack, which I won't bother for at least 4-5 weeks from pitch, I'll pull a large enough sample for a hydrometer reading and my FG.

I'll also take a refractometer reading from my hydrometer sample. I compare that to the FG from hydrometer to keep WCF stats.

Matt3989, I'm not at my computer at the moment, but thanks for the link. I'll check it out.

eliminate factors in the "can possibly go wrong" column if you can. rouse by "walking the barrel" instead. roll it like you would a big O2 or CO2 bottle.

 

[TAK]

eliminate factors in the "can possibly go wrong" column if you can. rouse by "walking the barrel" instead. roll it like you would a big O2 or CO2 bottle.

I'm not exactly sure what you mean by this; carboy on its side?

I tried swirling the carboy so I didn't have to crack the seal, sanitize the cane, and stick it in. I've seen the swirl method work before, but this yeast cake, even after only settling for a day or less, just didn't want to budge that way. Opening seemed the only way to get the cake back up.

 

[Billy-Klubb]

I'm not exactly sure what you mean by this; carboy on its side?

I tried swirling the carboy so I didn't have to crack the seal, sanitize the cane, and stick it in. I've seen the swirl method work before, but this yeast cake, even after only settling for a day or less, just didn't want to budge that way. Opening seemed the only way to get the cake back up.

not on it's side, but more like a 45 degree angle or so.

 

[EarlyAmateurZymurgist]

Yes, rousing does, in fact, work, especially with highly flocculent yeast strains. Anyone who has visited a traditional British brewery has seen the shower head looking device that British brewers use to rouse and aerate yeast. This device literally sprays fermenting wort.

One can see this device in action at the Timothy Taylor Brewery at time 1:07 in the video linked below:

http://timothytaylor.co.uk/img/video/Timothy Taylor - Fermentation Section.webm


Black Sheep uses the same device:

http://www.youtube.com/watch?feature=player_embedded&v=KJmLNj14C_w#t=20

All of the Peter Austin/Alan Pugsley designed and built breweries rouse and aerate the Ringwood yeast on the second day of fermentation.

 

[DoWBrewer]

I rouse the yeast daily once my kruesen drops. I have noticed that my fermentation completes more quickly and that my final gravity is typically a few points lower. I would doubt it helps with a stuck fermentation. I have found that adding boiled sugar with some yeast nutrient about 3 days into fermentation can help with a stuck fermentation. I had a IIPA stuck at 1.020 and after making the addition it finished at 1.010. I also think swirling daily helps with dry hop extraction.

Having said all of that, I would like to see actual data on the effect.

 

[SuperX]

For my two current batches, I have roused the yeast in both batches (Pacman & WLP002). Yesterday, after 2 weeks, I took hydrometer readings in both batches and put them back in the closet. This morning, the Pacman is bubbling merrily, the 002 somewhat slower. This could be because of oxygen getting into the bucket when I used the thief to take a sample, or from the movement of the bucket. Either way, it seems I've roused the yeast to a level I never saw just swirling the buckets.

 

[TAK]

not on it's side, but more like a 45 degree angle or so.

Maybe it's just this batch, but I can't get this to work. This was a huge starter, I estimated it at 700 billion cells per yeastcalc.com, and a huge beer. So, I think it's just the thickness of the yeast cake that prevents it from moving when I swirl or do as you mentioned.

 

[duboman]

Maybe it's just this batch, but I can't get this to work. This was a huge starter, I estimated it at 700 billion cells per yeastcalc.com, and a huge beer. So, I think it's just the thickness of the yeast cake that prevents it from moving when I swirl or do as you mentioned.

Wow, how big was this beer, that's a huge starter and you could have way over pitched!

 

[TAK]

wow, how big was this beer, that's a huge starter and you could have way over pitched!

og = 1.121

I can't recall the exact numbers, but after some research I settled on somewhere 650 and change for the optimal pitch. Easy to measure starter steps put me at 690 and change per calculations.

 

[duboman]

og = 1.121 I can't recall the exact numbers, but after some research I settled on somewhere 650 and change for the optimal pitch. Easy to measure starter steps put me at 690 and change per calculations.

What yeast for that amount of alcohol and what is the current gravity reading? If you are around 1.030 I really don't think it's going lower.......

What is your apparent attenuation at?

 

[TAK]

Well, I'll preface this by saying again that I haven't taken an FG reading yet. All I have right now are a couple of refractometer readings. Those suggest that I'm probably somewhere around 1.025-1.030, which would be 75-79% AA. So, I agree, I'm at or near the finish line.

Yeast is WLP007.

 

[duboman]

Well, I'll preface this by saying again that I haven't taken an FG reading yet. All I have right now are a couple of refractometer readings. Those suggest that I'm probably somewhere around 1.025-1.030, which would be 75-79% AA. So, I agree, I'm at or near the finish line. Yeast is WLP007.

Well then you should take a hydrometer reading and you'll probably find that the beer is done

 

[TAK]

Ah, patience will yield my true FG. I want to leave it in primary for at 4-5 weeks. I'll take a large enough sample for FG when I rack to secondary.

 

[MindenMan]

My house yeast is ESB 1968, and it flocs like crazy as the fermentation is slowing down. Depending on what beer I have brewing, the yeast cake can be fairly thick and dense. I start swirling my fermentation bucket like there is no tomorrow. Tilt it slightly and swing for the fence, so to speak. I have noticed I get a lot of bubbles released when I swirl it. I used to think it meant the fermentation wasn't done, but now I know better. I usually wait at least three weeks in the fermenter or longer, to allow for cleanup if the yeast needs it or not. If I am not in a hurry to reuse the yeast cake, or that particular bucket. ( some of my buckets have spigots set at different heights) When I notice the fermentation is very slow moving, I too raise the temperature a degree or two every day until I get to 72* F or so. Just my .02.

 

[duboman]

Ah, patience will yield my true FG. I want to leave it in primary for at 4-5 weeks. I'll take a large enough sample for FG when I rack to secondary.

Why4-5 weeks if you are going to secondary? If the beer is done fermenting and you want to clear and bulk condition it then just rack it over, there is no sense keeping it in primary that long if it's done. I understand patience but I don't understand what you're trying to achieve.

I also really don't understand why you posted this thread, honestly. If your not taking a reading then you don't know it's stuck so your OP really makes no sense to me, asking for advice and comment about something that really isn't even pertinent to what you're doing

 

[TAK]

Why4-5 weeks if you are going to secondary? If the beer is done fermenting and you want to clear and bulk condition it then just rack it over, there is no sense keeping it in primary that long if it's done. I understand patience but I don't understand what you're trying to achieve.

I primary most of my beers for 4 weeks, as I know many others on this forum do too. I know this is also a hotly debated topic on this forum, but if I do it for most of my beers, a big barley wine would be an odd choice to break the status quo.

I err on the side of long primaries in part because I feel that the yeast still has a role to play after it's attenuated. More so, I long primary because it's easy. This beer is a week in the primary today, and I don't actually know if it's done. I could crack it open every day to take gravity readings until I verify that it's not moving. For me though, it makes more sense to just let it sit for a month. As long as the attenuation looks good at that point, I know it's done.

I also really don't understand why you posted this thread, honestly. If your not taking a reading then you don't know it's stuck so your OP really makes no sense to me, asking for advice and comment about something that really isn't even pertinent to what you're doing

My OP neither asks for advice directly, nor do I mention stuck fermentations. Going into this big beer, I saw recommendations on other threads to rouse yeast as one method to give the yeast the best fighting chance in a high gravity beer, particularly with flocculent strains like mine. So, in my OP I was more interested in rousing yeast as a method to achieve the lowest apparent attenuation in a big bear, assuming that fermentation is moving along nonetheless. E.g. might rousing bring it down to 1.025, rather than 1.030 without? Stuck fermentations were brought up in subsequent posts.

 

[duboman]

Well then, had you said earlier the beer was only a week in the primary my replies certainly would have been completely different

Back to our regularly scheduled program......

 

[TAK]

How about just helping a flocculent strain along? I ask at this particular moment because I have a barley wine 5 days in with WLP007.

This is on the 1st page.