Can too much yeast harm a brew?
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brewprint
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Yes don't do it!
I always underpitch. I use a yeast calculator and subtract by 2/3.
Just kidding. Yeast pitching is truly over rated. I always under pitch. That's not a joke. But I use the same amount for every brew no matter what gravity and my fermentation is always complete.
I guess if there is truly a stuck fermentation (I've never seen one) then more yeast could help.
I always underpitch. I use a yeast calculator and subtract by 2/3.
Just kidding. Yeast pitching is truly over rated. I always under pitch. That's not a joke. But I use the same amount for every brew no matter what gravity and my fermentation is always complete.
I guess if there is truly a stuck fermentation (I've never seen one) then more yeast could help.
ColoHox
Compulsive Hand Washer
Overpitching can cause some issues. It will likely not destroy your beer though.
Overpitching can decrease ester production during fermentation, decrease mouthfeel/body, and potentially give meaty/soy off-flavors as the yeast die.
You can try restarting a fermentation by pitching properly rehydrated dry yeast, an active starter of liquid yeast, or swirling your fermenter to rouse the yeast. You can also try warming the fermenter up a few degrees.
What gravity are you stuck at and what was your SG?
Overpitching can decrease ester production during fermentation, decrease mouthfeel/body, and potentially give meaty/soy off-flavors as the yeast die.
You can try restarting a fermentation by pitching properly rehydrated dry yeast, an active starter of liquid yeast, or swirling your fermenter to rouse the yeast. You can also try warming the fermenter up a few degrees.
What gravity are you stuck at and what was your SG?
Vamptrump
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So there are two risks that exist.
1) Over pitching: This will prevent the yeast from going through a proper growth cycle and could result undesired flavors.
2) Under pitching: This will cause the yeast to take longer to reach the desired population, from this you will obtain more generations of the yeast being generated and the flavors associated with this. This too can result in undesired flavors.
What I'm getting at here is to pitch as needed for the gravity and style you are brewing. You can use calculators like http://www.mrmalty.com/calc/calc.html to determine appropriate pitching rates.
*Disclosure* I'm no micro-biologist, and I've only been brewing for little under a year. This is all based on what I've read and lacks real world experience.
1) Over pitching: This will prevent the yeast from going through a proper growth cycle and could result undesired flavors.
2) Under pitching: This will cause the yeast to take longer to reach the desired population, from this you will obtain more generations of the yeast being generated and the flavors associated with this. This too can result in undesired flavors.
What I'm getting at here is to pitch as needed for the gravity and style you are brewing. You can use calculators like http://www.mrmalty.com/calc/calc.html to determine appropriate pitching rates.
*Disclosure* I'm no micro-biologist, and I've only been brewing for little under a year. This is all based on what I've read and lacks real world experience.
brewprint
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My real world experience is that underpitching is the way to go. If everyone wants to go ahead and waste they're LME to make these giant starters because this is what everyone says to do; to each their own.
I know my beer turns out fantastic and I don't use yeast calculators any more, and haven't for quite a long time.
Back to the original question, tossing 2-3 packets of dry yeast into a fermentation that's mostly done won't "destroy a beer". What it's most likely to do is simply create a more yeasty beer.
If you really feel the need to toss more yeast (most often not the solution) into a batch that's already been fermenting a few weeks, it's best to make a starter and pitch it at high krausen.
You can't "destroy" a beer with yeast. Just pitch the appropriate amount of yeast based on gravity, volume and yeast age. Use calculators as a guide.
It sounds like the OP is a beginner brewer so the posters advice about under-pitching is poorly directed. OP, pitch the "correct" amount and you shouldn't have issues with stalled fermentation. If there is stalled fermentation you can gently swirl the fermenter to resuspend some of the yeast. I've never had to do this but other posters have suggested it.
It sounds like the OP is a beginner brewer so the posters advice about under-pitching is poorly directed. OP, pitch the "correct" amount and you shouldn't have issues with stalled fermentation. If there is stalled fermentation you can gently swirl the fermenter to resuspend some of the yeast. I've never had to do this but other posters have suggested it.
Yes, you can ruin a beer with too big a pitch but it is unusual for that to happen to a home brewer. Before I relate my single experience I'll point out that you are more likely to ruin a beer by underpitching/underoxygenating than over pitching so that IMO the advice to underpitch here is very bad advice. Stick to the million cells/mL per °P rule of thumb and you should be OK.
The single event in which it happened to me involved a 'club beer' to commemorate the 30th anniversary. It was to be a barley wine and my demand was that the clubs members brew it on my equipment (as opposed to the 30th anniversary where I brewed it on my equipment). So they did. Somebody showed up in the middle of the afternoon with a carboy half full of paste (note that says paste, not starter) which he had gotten from one of the local brew pubs. I said "You want me to put that in the beer". They said 'Yes'. I said "All of it?", They said "Yes" so I thinned it out with chilled wort and stuck the yeast feed line into the carboy. This was for 1-1/2 bbl beer. The next morning the beer was trying to climb out of a 2-1/2 bbl fermenter. To make a long story short the beer got over attenuated, was thin and insipid and just a big disappointment to me and I think everyone else.
The single event in which it happened to me involved a 'club beer' to commemorate the 30th anniversary. It was to be a barley wine and my demand was that the clubs members brew it on my equipment (as opposed to the 30th anniversary where I brewed it on my equipment). So they did. Somebody showed up in the middle of the afternoon with a carboy half full of paste (note that says paste, not starter) which he had gotten from one of the local brew pubs. I said "You want me to put that in the beer". They said 'Yes'. I said "All of it?", They said "Yes" so I thinned it out with chilled wort and stuck the yeast feed line into the carboy. This was for 1-1/2 bbl beer. The next morning the beer was trying to climb out of a 2-1/2 bbl fermenter. To make a long story short the beer got over attenuated, was thin and insipid and just a big disappointment to me and I think everyone else.
Vamptrump
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I found this article to help illustrate the affects of over-pitching, under-pitching, and controlled-pitching. http://sciencebrewer.com/2012/03/02/pitching-rate-experiment-part-deux-results/
tl;dr:
Over-pitching resulted in a thinner one-dimensional beer. The yeast didn't have the chance to put off desired esters and phenolics. Under-pitching resulted in too many esters making the beer taste of apple, pear, and peach. The controlled-pitching allowed for spice and phenolics to show in the beer. The author stated Control > Over > Under.
tl;dr:
Over-pitching resulted in a thinner one-dimensional beer. The yeast didn't have the chance to put off desired esters and phenolics. Under-pitching resulted in too many esters making the beer taste of apple, pear, and peach. The controlled-pitching allowed for spice and phenolics to show in the beer. The author stated Control > Over > Under.
Infidel
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The original question, changing the words a little - "restarting a stuck fermentation". Definitely better than doing nothing. Adding more yeast, good. See above post and read a little on rehydrating (consider "go-ferm"). There is nothing wrong with adding 2-3 packets of dry yeast to a medium/high gravity beer other than the discomfort of paying retail for yeast.
Comments are correct on under pitching / over pitching & flavors but the OP is about something which to the best of our knowledge stopped fermenting. We are making the assumption this fact was determined with a hydrometer.
See the Scott Labs guide to using go-ferm if you have access to that product. If you don't have access to go-ferm, don't rehydrate with nitrogen or a standard yeast nutrient. Without go-firm, try boiled yeast as a rehydration nutrient. The boiled yeast is cheap / dead yeast which you are trying to break apart during the boil to release the nutrients stored in the dead yeast cells. Acclimate the rehydrating yeast to the alcohol content by adding a little of the stuck batch at a time until it is 50% of the volume of the rehydrated yeast solution. These instructions aren't extremely clear. Search for Scott Labs Fermentation Handbook / Go-Ferm for better instructions.
Comments are correct on under pitching / over pitching & flavors but the OP is about something which to the best of our knowledge stopped fermenting. We are making the assumption this fact was determined with a hydrometer.
See the Scott Labs guide to using go-ferm if you have access to that product. If you don't have access to go-ferm, don't rehydrate with nitrogen or a standard yeast nutrient. Without go-firm, try boiled yeast as a rehydration nutrient. The boiled yeast is cheap / dead yeast which you are trying to break apart during the boil to release the nutrients stored in the dead yeast cells. Acclimate the rehydrating yeast to the alcohol content by adding a little of the stuck batch at a time until it is 50% of the volume of the rehydrated yeast solution. These instructions aren't extremely clear. Search for Scott Labs Fermentation Handbook / Go-Ferm for better instructions.
Vamptrump
Well-Known Member
I have to agree. I completely forgot this was talking about stuck fermentation and instead of the affects of over pitching.
I've personally added more yeast to a big beer (~OG 1.102) because the fermentation stuck. If a stuck fermentation is truly the case, I see no harm in adding more yeast to get it going. But with limited information (how long, temperature, etc) regarding what is stuck this could be a good or bad thing and missing underlying issues.
tl;dr: Pitch correctly at the start, but if fermentation is truly stuck, analyze the situation and if it truly is a yeast issue, then pitch more.
Soulshine2
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when you know that yeast is a living thing ...It eats , divides and shuts down once its alcohol tolerance is reached (attenuation) . I normally use 11.5 g packets of Fermentis dry yeast per the beer style in 5 and 6 gallon batches, numbers and gravity goals met nearly every time as predicted.
I read about commercial pitching rates for a 5 gallon batch ,and the cell count required per size of the batch ,optimal temperature range, factor in the cell count per package , I'll pick a dry yeast every time.
with exception to my last brew yesterday and I reached for the yeast slurry I harvested 2 weeks ago. Just so happens the wheat portion of the grain bill on the previous batch was nearly the same as the one I pitched to, otherwise I would dry pitch a single packet. Plenty there to do the job.
