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Top Cropping Yeast (in Pictures)

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Wolfy

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Top cropping is a useful way to harvest clean, fresh and healthy yeast, it's done while the yeast is actively fermenting and it's best pitched immediately into a new batch of beer.

When working with yeast, it's best to be as sanitary/sterile as possible. Chemical sanitizers (like Starsan) are useful, but using heat to sanitize should be better again.
The only equipment needed to top crop yeast is a suitable spoon and container for the yeast. An all-stainless ($2 Asian soup-serving) spoon and pyrex jug work well, and can be heat-sanitized (in boiling water for 15mins).


While the actual top cropping procedure is deceptively simple, it does require a few things to 'go right' before it can be attempted.

Firstly you need to be working with a yeast that allows top cropping; during the active fermentation phase, the yeast will float on-top of the wort with a sizable, active, 'rocky' type head. The yeast (most often top-fermenting Ale strains), wort, temperature and other factors will determine if top cropping is possible (sometimes it may even be possible to top-crop a bottom-fermenting lager strain).


The trick to successful top cropping is getting the timing right, you want to top crop the yeast when it's most active, when there is a large amount of healthy fresh yeast floating on-top of the wort, usually this time is called 'high krausen'. In some situations this might be over a 2 or 3 day period, in other cases it might be a matter only just hours, attempting to top crop to early or too late will not work if there is not sufficient yeast to harvest.

As can be seen in both the photos above, two days after pitching, the yeast (Wyeast London Ale III, Wy1318) is forming a raft 70-100mm in height above the wort with a nice rocky/solid/yeasty head, making it the ideal time to harvest the yeast by top cropping. However, the exact time when yeast can be top-cropped depends on many individual factors and there is no generic rule that can be followed, the fermenting beer must be checked periodically and top cropped when the yeast is ready.

Top cropping is only possible when using a fermenting vessel that allows access to the surface-yeast, top cropping with enclosed fermentors is not usually possible.

Using the sanitized spoon, first skim-off (and discard) any trub/break/protein or hop debris that sometimes floats on top of the yeast:


Then scoop up the fresh, clean yeast:


Continue the process to harvest enough yeast as required:


Since we have harvested only clean, fresh and 'pure' yeast, somewhere about 50-150ml should be adequate for pitching into a standard sized batch of fresh wort:


Depending on the conditions and time the yeast is harvested, it's possible that the yeast can be top-cropped again later (sometimes it will take only hours for the yeast to be ready for additional harvesting):

(Photo taken a short time after the top cropping shown above)

Top cropped yeast, harvested at high krausen is fresh, healthy and active, so it's best to pitched immediately into a new batch of fresh similar composition wort, where it will likely 'kick off' very quickly. If you are not able to use freshly top cropped yeast, it might be better to wait and harvest the yeast after fermentation has completed and the yeast has settled.
 

robbo5253

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Thanks Wolfy.
Another great artie to help assist other brewers!

Cheers

Robbo
 

Muscovy_333

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Top cropping is a useful way to harvest clean, fresh and healthy yeast, it's done while the yeast is actively fermenting and it's best pitched immediately into a new batch of beer.

When working with yeast, it's best to be as sanitary/sterile as possible. Chemical sanitizers (like Starsan) are useful, but using heat to sanitize should be better again.
The only equipment needed to top crop yeast is a suitable spoon and container for the yeast. An all-stainless ($2 Asian soup-serving) spoon and pyrex jug work well, and can be heat-sanitized (in boiling water for 15mins).


While the actual top cropping procedure is deceptively simple, it does require a few things to 'go right' before it can be attempted.

Firstly you need to be working with a yeast that allows top cropping; during the active fermentation phase, the yeast will float on-top of the wort with a sizable, active, 'rocky' type head. The yeast (most often top-fermenting Ale strains), wort, temperature and other factors will determine if top cropping is possible (sometimes it may even be possible to top-crop a bottom-fermenting lager strain).


The trick to successful top cropping is getting the timing right, you want to top crop the yeast when it's most active, when there is a large amount of healthy fresh yeast floating on-top of the wort, usually this time is called 'high krausen'. In some situations this might be over a 2 or 3 day period, in other cases it might be a matter only just hours, attempting to top crop to early or too late will not work if there is not sufficient yeast to harvest.

As can be seen in both the photos above, two days after pitching, the yeast (Wyeast London Ale III, Wy1318) is forming a raft 70-100mm in height above the wort with a nice rocky/solid/yeasty head, making it the ideal time to harvest the yeast by top cropping. However, the exact time when yeast can be top-cropped depends on many individual factors and there is no generic rule that can be followed, the fermenting beer must be checked periodically and top cropped when the yeast is ready.

Top cropping is only possible when using a fermenting vessel that allows access to the surface-yeast, top cropping with enclosed fermentors is not usually possible.

Using the sanitized spoon, first skim-off (and discard) any trub/break/protein or hop debris that sometimes floats on top of the yeast:


Then scoop up the fresh, clean yeast:


Continue the process to harvest enough yeast as required:


Since we have harvested only clean, fresh and 'pure' yeast, somewhere about 50-150ml should be adequate for pitching into a standard sized batch of fresh wort:


Depending on the conditions and time the yeast is harvested, it's possible that the yeast can be top-cropped again later (sometimes it will take only hours for the yeast to be ready for additional harvesting):

(Photo taken a short time after the top cropping shown above)

Top cropped yeast, harvested at high krausen is fresh, healthy and active, so it's best to pitched immediately into a new batch of fresh similar composition wort, where it will likely 'kick off' very quickly. If you are not able to use freshly top cropped yeast, it might be better to wait and harvest the yeast after fermentation has completed and the yeast has settled.

Thanks Wolfy, informative as ever...

I recently Top Cropped my German Ale in the exact same manner. I sealed in sterile glass jars and placed in the fridge immediately to 'crash' the yeast to sleep. I have a nice clean milky sample that has settled out to the bottom of the jar. Since I have not piched immediately is their anything I need to consider when re-activating? I was going to treat it like a liquid yeast sample. I.e. rouse as a starter and pitch when active. This method has yield a far better amount of viable yeast than my usual rinsing..
 

Wolfy

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I recently Top Cropped my German Ale in the exact same manner. I sealed in sterile glass jars and placed in the fridge immediately to 'crash' the yeast to sleep. I have a nice clean milky sample that has settled out to the bottom of the jar. Since I have not piched immediately is their anything I need to consider when re-activating? I was going to treat it like a liquid yeast sample. I.e. rouse as a starter and pitch when active. This method has yield a far better amount of viable yeast than my usual rinsing..
It's my understanding that as yeast finish the fermentation process they prepare for dormancy by building up 'food' reserves (glycogen and trehalose). They might help extend the shelf-life of the stored yeast, but most importantly, when pitched into a new batch of wort those carbohydrates help the yeast adapt, acclimatize and start a healthy fermentation. If you top-crop you are taking the yeast while it's most active (and essentially in a feeding-frenzy), then if it's stored immediately (essentially starving it) it may not be 'as prepared' for storage or 'as prepared' for future fermentation. I presume using a stater before pitching the yeast (not having to do so is another advantage of top-cropping and pitching immediately) would get the yeast ready for your new ferment.
 

thylacine

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Great pics and info. Thanks...

1) "... However, the exact time when yeast can be top-cropped depends on many individual factors and there is no generic rule that can be followed, the fermenting beer must be checked periodically and top cropped when the yeast is ready..."

Wyeast recommendations when to crop & the discarding of the first skim: "When Yeast Should be Harvested"

"...Open Vessels (Top Cropping): Yeast can be harvested once the gravity has dropped below 50% of original gravity. First head will rise approximately 24-36 hours into fermentation.
Discard 1st skim (dirt skim). A clean, 2nd head will rise which can be harvested with a 2nd skim..." http://www.wyeastlab.com/com-yeast-harvest.cfm

2) "...Top cropping is only possible when using a fermenting vessel that allows access to the surface-yeast, top cropping with enclosed fermentors is not usually possible..."

re top-cropping from a carboy, example w/pics. http://karlisbeer.blogspot.com.au/2010/03/...rom-carboy.html

Cheers
 

Wolfy

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Wyeast recommendations when to crop & the discarding of the first skim: "When Yeast Should be Harvested"

"...Open Vessels (Top Cropping): Yeast can be harvested once the gravity has dropped below 50% of original gravity. First head will rise approximately 24-36 hours into fermentation.
Discard 1st skim (dirt skim). A clean, 2nd head will rise which can be harvested with a 2nd skim..." http://www.wyeastlab.com/com-yeast-harvest.cfm
Interesting point about the 50% of OG remark, it's something to consider, and might help ensure that not too much yeast is harvested too early. However, it would require more constant monitoring of the gravity than I think most home-brewers perform and from what I understand, it's hard enough for some home brewers to catch the yeast at the optimum time for top cropping anyway. :p
I wonder if the 'dirt skim' is simply easier for a commercial brewer and if it's the same as a home brewer simply removing (and discarding) the trub and muck that sometimes floats ontop before harvesting the clean yeast underneath.
While they don't say when the 2nd skim can be performed, but it's interesting that they imply the beer will have dropped below 50% of the OG within 24-36h.
Looks like the same idea as I posted here: Easy Yeast Top Cropping
I've also top cropped with a spoon in my jerry-fermentor, it's just more difficult than the more common open barrel fermentors which is why I said "not usually possible", maybe "not as easily possible" would have been better. ;)
 

chefsantos

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Wolfy you really are the yeast guru .
 

mje1980

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I love to top crop, its easy and when you pitch into a new batch it goes nuts very quickly.

Question wolfy, I find some strains ( uk ales ) throw a foamy head, but not always the thick creamy yeasty goodness. It seems just plain white with a bit of what looks like hop matter. I never know if i can crop these yeast strains. Do you only crop the thick gooey tan coloured krausen, or both the thinner, white krausen?
 

Amber Fluid

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Another great thread Wolfy....

Do you think it might be an idea to have a list of what yeast can be top cropped for those who are unaware of the strains that aren't bottom dwellers?
 

Yob

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:lol: I was just doing this last night for the first time..

1.JPG

Some crazy Yeast some guy gave me ;)

2.JPG

Very fluffy, too fluffy in fact to get a decent harvest

3.JPG

After scooping

4.JPG

The beast this morning.

Christ Wolfy, what planet is that Greenbelt from :blink:

:icon_cheers:
 

Wolfy

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After posting the pictures above (and being surprised how little gunk there was floating on the top of the yeast) I recalled that about 16 hours after pitching the yeast (when there was already a krasuen starting to form) I shook the fermentor around to re-aerate it a bit more. This might also be the equivalent of Wyeast's suggestion of discarding the 'dirty skim'.
Question wolfy, I find some strains ( uk ales ) throw a foamy head, but not always the thick creamy yeasty goodness. It seems just plain white with a bit of what looks like hop matter. I never know if i can crop these yeast strains. Do you only crop the thick gooey tan coloured krausen, or both the thinner, white krausen?
Rather than saying yes or no, I think the best answer is to try it and see. Skim it and store the skimmed-stuff in a jar or jug and see how much yeast you have harvested when the foam has settled.
Do you think it might be an idea to have a list of what yeast can be top cropped for those who are unaware of the strains that aren't bottom dwellers?
Likely a good idea, but even with the list there are other factors that determine how yeast behaves which could mean that something on the list couldn't be top cropped in specific situations or something not on the list could be in others. A list would then cause contention or confusion if someone was following it without thinking logically (which seems to happen a bit). I think the best practice (as suggested above) is to try it and see, the actual top cropping procedure is so simple and easy (if sanitation issues are taken care of) there is no reason not to try it and see how it goes, and how much yeast is harvested.
...
Very fluffy, too fluffy in fact to get a decent harvest
...
Christ Wolfy, what planet is that Greenbelt from :blink:
Sounds like the same sort of white-fluffy that mje1980 was asking about, how much yeast did you get when the fluffy-foam had settled?
Looks like you could get enough to pitch into a new batch with the size of the krasuen there. ;)

Greenbelt is from planet (Austin, the capital of) Texas ... which might explain why it's big/brash/overboard? ;)
 

Yob

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how much yeast did you get when the fluffy-foam had settled?
Looks like you could get enough to pitch into a new batch with the size of the krasuen there.
2 tenths of feck all in what's pictured above ;) I guess (if I had the time) I could collect over a couple of days easily... Ive had to clean it twice today already so probably should have collected it all.. B) should collect a small sample anyway I spose...

:icon_cheers:
 

Yob

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it occurred to me this morning that next time I ferment with this (beast) I should use the lid with a blowoff tube into sterile water to collect the yeast, then rinse as per normal practice.

I think this practice with a volcanic 'fluffy' yeast will be much better suited.

:icon_cheers:
 

Coldie

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Another great post Wolfy. Just want to say a big thanks to all you guys who take the time to post and share your expertise with newbies like myself.
 

Wolfy

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Mike L'Itorus

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I wonder if the 'dirt skim' is simply easier for a commercial brewer and if it's the same as a home brewer simply removing (and discarding) the trub and muck that sometimes floats ontop before harvesting the clean yeast underneath.
I've never bothered with discarding the first skim, as done in commercial practice, essentially because, as homebrewers, we have the luxury of working in small scale, and can be selective with the yeast we remove, tatgeting only the clean areas. Commercial scale brewing simply doesn't have that luxury, as you say.

In relation to storage of top cropped yeast....well, yes, yeast builds nutrient reserve at the end point of the fermentation, and so one would think that storage could be problematic. What I've found in practice, though (several years of top cropping over countless batches) is that the storage capability of top cropped yeast is better than that of bottom harvested yeast collected post-fermentation. My opinion on this is that it is likely to do with the purity of the sample. I find that if using within a short period (ie, a week or two), no particular startup procedure is required, other than, perhaps, using just a tad more yeast than if it were to be immediately pitched, which, with a true top cropping strain is no problem at all, given that a single krausen normally has enough yeast available for harvest from a single skim to directly pitch multiple batches of wort (obviously, this depends on volume and wort gravity).
 

Danhutch333

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What an excellent resource this site is.

Posts like this enable a noob like myself to try try things mid-brew which increase my knowledge base ten-fold.

Very much appreciated!

Hutchy
 

Bribie G

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When I get my brewery up and running in Northern Mexico in a few weeks I'm renewing all my yeast stocks and already have a Wyeast 1768PC calling out to me. My house beers are going to be American Wheat with 1272 and UK special bitters with the 1768PC and also of course 1469 so I'll be skimming like buggery. Thanks for the thread Wolfy, edit: up to now I've been doing the lazy thing and just saving and pitching yeast cake but have been getting off flavours and poor stability in many of my batches, so this will be an opportunity to ratchet up my skills one notch. I was actually looking at a pyrex jug the other day.
 

micblair

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second skim vs dirt skim. I know which one I will be re-pitching from.

image.jpg


image.jpg
 

bear09

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Perhaps slightly :icon_offtopic: .....

IN regards to this post and this link (http://karlisbeer.blogspot.com.au/2010/03/top-cropping-yeast-from-carboy.html) does anyone here know where I can buy those little rubber lids for a carboy?

To be honest top cropping does not really interest me but I am SICK TO DEATH of having to clean up the mess on the outside of my carboy after a crazy fermentation. Essentially I am after a sanitary blow off tube option for a carboy.

Thanks all...

Great pics and info. Thanks...

1) "... However, the exact time when yeast can be top-cropped depends on many individual factors and there is no generic rule that can be followed, the fermenting beer must be checked periodically and top cropped when the yeast is ready..."

Wyeast recommendations when to crop & the discarding of the first skim: "When Yeast Should be Harvested"

"...Open Vessels (Top Cropping): Yeast can be harvested once the gravity has dropped below 50% of original gravity. First head will rise approximately 24-36 hours into fermentation.
Discard 1st skim (dirt skim). A clean, 2nd head will rise which can be harvested with a 2nd skim..." http://www.wyeastlab.com/com-yeast-harvest.cfm

2) "...Top cropping is only possible when using a fermenting vessel that allows access to the surface-yeast, top cropping with enclosed fermentors is not usually possible..."

re top-cropping from a carboy, example w/pics. http://karlisbeer.blogspot.com.au/2010/03/...rom-carboy.html

Cheers
 

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