Author Topic: Ask the Experts: Chris White & Jamil Zainasheff  (Read 4980 times)

Offline duncan

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Ask the Experts: Chris White & Jamil Zainasheff
« on: March 15, 2013, 09:37:15 AM »
Chris White
Chris White is President of White Labs and Co-Author of Yeast: The Practical Guide to Beer Fermentation.

Chris' interest in homebrewing came from undergraduate studies at UC Davis, when he signed up for Michael Lewis' brewing course. Chris then completed a Ph.D. thesis on yeast biochemistry at UC San Diego. He founded White Labs as a yeast and fermentation laboratory for brewers and homebrewers in 1995. He is active as President of White Labs, and enjoys growing the company worldwide and moving into new areas of fermentation such as distilled products and wine. Chris White is also a faculty member of Siebel Institute of Technology in Chicago. Chris is a member of the American Society for Brewing Chemists and the Master Brewers Association of America. He enjoys traveling, golf, talking beer, and barbeques with friends.

Jamil Zainasheff
Jamil Zainasheff is an award-winning homebrewer, beer judge, author, and host of "The Jamil Show" and "Brew Strong" shows on The Brewing Network. Jamil has brewed an award winning example of every style of beer described in the Beer Judge Certification Program (BJCP) Style Guidelines. He has co-authored two critically acclaimed brewing books, Brewing Classic Styles and Yeast: The Practical Guide to Beer Fermentation. Jamil's newest venture is Heretic Brewing Company, located in Pittsburg, California.
« Last Edit: March 15, 2013, 09:57:05 AM by duncan »

Offline duncan

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #1 on: March 15, 2013, 09:38:05 AM »
Oscar from Pennsylvania asks:
On a recent visit to Holland, my aunt, who is just learning of my new found homebrewing hobby, told me of a friend of hers who used to be a brewer for Groslch. He told her proudly they got new yeast from Denmark every two weeks. Later on during the visit, a brewer from Brewery Het Ij (pronounce het aye), a micro brewery in Amsterdam, told me they have propagated the same "house" strain for 25 years now. I have also taken note that many of the recipes I read about from American breweries list "proprietary strain" as their yeast used. So which is it? Does the yeast get tired if used over and over again? Or, if you pamper your yeast and get it used to living with you, can you propagate a strain to be your best friend for ever, allowing it to adapt to the conditions in your brewery? I know this may not be what our good friends at White& Wyeast want to hear, but then again, as a home brewer the thought of having a house strain for your "special" beer flavors is intriguing.

Thanks


Chris and Jamil answer:
You can keep yeast forever, given the right conditions. Of course, for most brewers contamination eventually increases to a point where they want to start with a fresh pitch of yeast.

Yeast do mutate, and those mutations will build up over time, changing the yeast in ways that may or may not be desirable. Much of it depends on the brewer, how you handle the yeast and how you select the yeast to use with the next batch. If you only select the yeast that does well and produces flavors you like, perhaps over time it will change enough that you can consider it your own proprietary strain.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #2 on: March 15, 2013, 09:39:14 AM »
Don asks:
I’m getting back into home brewing and trying to improve my brewing process while still keeping the fuss to what is practical. My research so far has confused me somewhat - the subject is head space in a primary fermenter and considering the practicalities of aerating. Whichever way you choose to aerate, whether by venturi transfer (e.g., via Wort Wizard) or an aquarium pump. As well as taking into consideration that some head space is required for the early boisterous phase of primary fermentation. What volume of initial head space should be considered for a venturi transfer or an adequate amount of pumping air via, for example, an aquarium pump - 20% of volume, 30%? Is this really an issue or am I creating unnecessary concern here?

Advice would be appreciated.


Chris and Jamil answer:
While it is probably possible to calculate the available O2 trapped in the headspace and later dissolved in the wort, it is not worth the trouble. Just make sure you have the right amount of space to allow for fermentation (or hook up a blow off tube). Measure the duration and any other settings that you use to add oxygen. Taste the beer once fermented. Keep notes. The next batch try to increase or decrease the oxygen added and see if your results improve. This is how I did it as a homebrewer. It didn’t matter what the actual number might be. When it tastes great, you have the right amount of O2.

One last thought. We are not fans of venturi devices for oxygenation. It is questionable how much oxygen is dissolved into the wort with these devices. It may be more effective to shake the fermenter. The worst part about venturi machines is that they pull in air and with it dust, which is not sanitary.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #3 on: March 15, 2013, 09:39:59 AM »
Jeffery asks:
1. I recently brewed an English IPA with an OG of 1.065 using WLP002. I made a proper starter, oxygenated from about 1 minute, and fermented at 65ºF rising to 67ºF at the end of fermentation. The beer ended up fairly fruity (cherry and almost a little fruity/tart), which was the opposite of what I was trying to accomplish. The only irregularity was that I over chilled the wort to 58ºF, pitched, and then brought the temp to 65ºF over about 3 hours. Can you offer some tips for reducing fruity esters with English yeasts? How cool could you go for the first couple days?

2. I brew a yearly Belgian Strong Golden that is one of my most successful beers. I use and love WLP570 for it, but It's always a hassle to get it to clear. I usually keg, fine with gelatin and then bottle later. This year the yeast made more sulfur than it has in the past. What factors influence sulfur production in beer yeast? I have been "burping" the kegs for the last couple months and the aroma is greatly reduced but not gone. With wine one must be cautious with H2S because it can form mercaptans and disulfides that are harder to get rid of than H2S. I have used CuSO4 at work for such problems. Is there a risk to allowing beer to have some sulfur for extended periods? Once bottled, it will never go away right?


Chris and Jamil answer:
You want to avoid stressing the yeast, causing them to express heat shock proteins with large temperature changes. It would have been better to change the wort temperature before pitching the yeast.

As for fruitiness, it is a complex question that depends on the pitching rates, oxygen levels, yeast health, nutrients, wort gravity, temperature, etc. Keep in mind that in general low cell counts + heat + oxygen will result in more ester production. Stress will cause yeast to produce more sulfur. Stress comes in many forms, but the most common causes would be temperature changes, high gravity worts, or a lack of certain nutrients. H2S is related to yeast growth, but normally the evolution of CO2 from fermentation will drive the sulfur off. Capping fermentation early or dropping the temperature early can trap more sulfur in the beer. Wort spoilage organisms can also create H2S.

It is important to taste your beer before kegging. If you notice that a flavor needs correcting, it is often easier to keep it in the fermenter and let the yeast help by raising the temp a little. H2S is quite volatile and mostly blows off, while SO2 can combine with aldehydes, forming compounds that persist.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #4 on: March 15, 2013, 09:40:54 AM »
Allen from New York asks:
I have some top cropping yeast questions. I have found an ”english" origin yeast that is a great top cropper and has a flavor profile I like. In your yeast book, you mention not using the "first skim" as it has proteins and such. My question; are you supposed to completely skim all yeast off the surface and discard it, then collect subsequent skims? I have been top cropping for over a year now, and I have just used the first skim because I am worried that discarding all the yeast from the surface of the beer will screw up the fermentation. Is discarding all the krausen i.e. first skim the proper method, or will it "stunt" the fermentation?

You also say in your book that using a wet weight of slurry is a decent way to measure the yeast slurry from batch to batch. As a top cropper, I have tried to be "consistent" with the amount of top cropped yeast (measured in grams) from batch to batch, but I have no idea if I am pitching the proper amount of cells. Is there any way to come up with a "weight range" of top cropped slurry for re-pitching (assuming the beer is brewed within two weeks with optimal storage)?

When top cropping, I try to "select" yeast about the same number of hours after the initial pitch for consistency. That is 48 hours for me. Depending on what the answer for the first question above, if I am to discard the first skim, when should I do the first skim (48 hours after pitch)? How long will it take to get a second skim (minutes or hours away)? I know the timing could be different by strain, but let us assume the yeast is great top cropper and not one that has to be trained to top crop.

Thanks in advance for your answers, and I loved the yeast book.


Chris and Jamil answer:
You just need to scrape off the very top of the yeast layer and that will get rid of most of the non-yeast material. If you want the purest yeast, the second crop after removing the first should be cleaner. However, not all strains will produce a second crop. If the strain you are working with produces another crop, then there is little need to worry. You might try pitching the same wort with yeast from the first crop and from the second crop. You might get a slightly different ferment from one versus the other. One might be slightly more attenuative or produce a different flavor, so try both ways.

As far as weight, the old British rule of 1 lb of yeast per British barrel might be something you could use. Those brewers were often top cropping, so the number might work well for you.

Your timing sounds good. 48 hours is about right, depending on the yeast and conditions. If you are discarding the first crop then take care of that somewhere between 24 to 36 hours.

Offline duncan

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #5 on: March 15, 2013, 09:41:55 AM »
Andrew from Maryland asks:
I used to aerate starters by intermittent shaking and recently moved to a stir plate. My beer ferment profile: using WLP550,WY3711, WY3522-was fairly consistent.(as consistent as Belgian yeasts can be).Since I got the stir plate, I decant and pitch, get lag times of 6-12 hours, and furious ferments lasting 24-36 hours.

The puzzling part is now the yeast stays in suspension for 7-10 days and will suddenly drop like a rock. I have hit low end FGs depending on the beer but not always full attenuation which leaves some residual sweetness. The beer is still good but I would like to know what's causing the yeast to remain in suspension for so long so I can re-jigger my fermentation management. I use the Mr. Malty pitching calculator. My starter wort is around 1.035, and I add yeast nutrient. I have not changed my brewing processes. I brush my teeth and say my prayers.

Thanks for making yourselves available for questions.


Chris and Jamil answer:
There are a couple things to consider. Are you getting lower or higher levels of measured attenuation or does the beer just seem sweeter to you and you are assuming it is not attenuating as much? A number of factors affect sweetness. It might be that the change in fermentation is producing more alcohols that have a sweet character to them. Or it might be that the change in pitch rate is resulting in more yeast surface area and it is pulling more of the hop bittering out of the beer when it settles.

Another consideration is how is your starter process? Often brewers will decant the starter before some of the more attenuative yeast have settled. This makes for a less attenuative fermentation, because you’ve thrown away the yeast that were still working. Sometimes in switching to a stir plate, brewers will leave the starter on there much longer than necessary. Growth is often complete in just a couple days, but they will leave the yeast sitting warm for a week. This ends up depleting the yeast reserves and weakening the yeast.

There are a few things you can try to help resolve this mystery.

First, you should try doing a forced ferment test. This will see what the actual terminal gravity might be for that wort/yeast combination. The second thing you might do is to take a gravity reading each day. We doubt that full attenuation was reached in 24 to 36 hours. If the gravity keeps dropping during the 7 to 10 days, then it is likely either you are not pitching enough yeast or the yeast are deficient in some nutrient or oxygen. You don’t mention the starting gravity of the beers you are making, but if they are high gravity, they may need more yeast, more nutrients, and more oxygen to fully attenuate. Another thing you can try if the previous efforts don’t solve the problem is to try fermenting with a well known, very consistent strain, such as White Labs WLP001. Do everything the same and see if you get the same result. If so, then it is certainly your starter process.

Offline duncan

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #6 on: March 15, 2013, 09:42:45 AM »
Robert from Washington asks:
I recently brewed a Munich Dunkel. When I started drinking the beer, I noticed a bit a diacetyll in the nose, nothing really in the taste. I used a single decoction from protein rest to saccharification rest. The grist was 10lbs munich light and 6 oz of chocolate. I used Wyeast Bavarian Lager from a local brewery and used a yeast starter. I did not add any yeast nutrient to the wort directly, just a small amount to the starter. I also do not have an aeration or oxygenation system. But, I'm thinking the diacetyl came from a deficiency of free amino nitrogen. Will adding yeast nutrient to the boil and adding more oxygen reduce the diacetyl in the finished beer with still doing a decoction? Is a decoction even necessary or can I achieve the same results with adding some melanoidin malt?

Second, I will be purchasing an oxygenation system. I was wondering how can I achieve the proper level of oxygen of 8-10 ppm? Is there a guideline I can reference or and equation to help calculate the proper levels based upon volume, gravity, etc...?

Thank you


Chris and Jamil answer:
It is important to know all of the aspects of fermentation to truly understand the source of a problem, like excessive diacetyl. Keep in mind that temperatures, pitching rates, yeast health, and yeast purity, all play a large role in diacetyl levels in beer. Without that information it is difficult to declare that the problem was from a nutrient deficiency and/or a lack of oxygen. However, it certainly is something that you should address if you are serious about brewing a quality lager. Chances are good that addressing these issues will have an impact on the amount of diacetyl. One more thing, you mention getting a pitch of yeast from a local brewery. When homebrewers do this, they often get more yeast than needed and over pitch. Over pitching can also cause a higher level of diacetyl in the finished beer, so try to measure the amount of yeast pitched and pitch the proper amount. Longer conditioning time on the yeast, especially at elevated temperature (diacetyl rest), can help reduce diacetyl.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #7 on: March 15, 2013, 09:43:25 AM »
Ben from Illinois asks:
I recently made my first yeast starter for my latest cream ale. I think I had a problem with infection in my Erlenmeyer flask. Before I used it I cleaned it and over cautiously sanitized with Iodophor. I made a small 1.045 wort with Pilsen DME. I then boiled it for 20 minutes, cooled down the flask in an ice bath, and pitched WLP810 San Fran lager yeast at about 68F.This was my fermenting temp. I covered it with tin foil and let it sit for 4 days in my kitchen. It smelled a little like sour wine on brew day. Against my better judgment I pitched it anyway, liquid and all. Although the beer is a young 2 weeks, it still smells sour. My big questions here are,

Should I use a bung and airlock for my starters? Tin foil just seems a little unsanitary and I think I just proved it with my sour cream ale. Did this happen as a characteristic of high temp lager yeast fermentation? Maybe too high? Or is this a characteristic of the young beer that will fade with a lagering period of a couple months?


Chris and Jamil answer:
Covering the flask with foil so that it hangs down about three inches all around should provide plenty of protection unless you have insects crawling around. You don’t want to use a stopper and airlock. It is harder to ensure it is sanitary and it can result in less air exchange for the starter.

We would have to taste the beer or starter to know for certain whether it is a bacterial, wild yeast, or other issue such as high levels of sulfur. The flavor you get from a warmer lager fermentation depends a lot on yeast strain.

Contamination is always a possibility with starters, which is why caution is needed. A good method is to use a Pyrex or Bomex flask and boil directly in the flask with the top covered with the foil. This will sanitize not only the wort, but the flask, and the foil. When it comes time to cool the starter, keep the foil on. When it comes time to add your yeast, work in a draft free area and do not uncover the flask any longer than is necessary.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #8 on: March 15, 2013, 09:44:19 AM »
Dan from New Jersey asks:
I understand that transferring the beer is mostly unnecessary when brewing beers of average gravity. Also from the information I've gathered autolysis is not a major issue at the home brew level if one happens to leave the beer for extended periods on the yeast cake. My method is to try to get a healthy fermentation using proper aeration and pitching rates, allow the beer to ferment out and then give it a few days to "clean up after itself." I will take a hydrometer reading and if the gravity is good and I don't smell or taste any diacetyl I go ahead and keg or bottle the beer. Here is my question. I have read a lot of forum posts where folks say leaving beer in the fermenter for much longer periods will drastically improve the flavor. I am talking anywhere from 3 weeks to 3 months, most of these posts claim it is the yeast "clearing up after itself". What I am wondering is after the yeast drop out and beer tastes ready to bottle or keg is the yeast actually doing anything in these extended time frames? Reading in your Yeast book I see maximums times of 15 hours lag phase, four days growth phase and ten days stationary phase, that comes to around fifteen days total. So if the beer appears ready to bottle or keg after 15 days will leaving on the yeast an extra week or multiple weeks have a major impact on the flavor? Also what exactly is the yeast doing, if anything in this time? I am sure it depends, but I hope you can clarify this a bit for me.

Thanks for your time


Chris and Jamil answer:
Your method is sound and I would question the wisdom of leaving beer on the yeast for much longer than what you outline in your process. Yes, the yeast (if healthy and not in a high alcohol environment) probably won’t cause any off flavors if the storage time is extended, but it really isn’t doing much to help the beer either, unless the beer quality was poor going into it. For example, perhaps someone had a fermentation that was sluggish, full of diacetyl, or other compounds. In that case, maybe it helped to rest on the yeast for a long period of time. However, you are doing the right thing. Ensure proper fermentation from the start with healthy yeast, proper pitching rates, nutrients, and temperature control. Perform a taste test and if there are no problems, package the beer.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #9 on: March 15, 2013, 09:45:00 AM »
Mark from Pennsylvania asks:
I’m enjoying your book on yeast. I have a microbiology background, so it’s been very interesting on a lot of levels. I have a question regarding storage of a yeast slurry under distilled water. Since, the yeast are in hibernation from the de-ionized water, I’ll need to wake them up before pitching. I won’t need a starter because I’ll already have lots of yeast from the slurry. I was thinking of letting the slurry warm to room temperature, decanting the water, adding some low gravity wort, and re-suspending the yeast several hours before pitching to let the cells acclimate themselves to the new environment. Does this sound like a plan?

Thanks in advance.


Chris and Jamil answer:
Yes, that sounds like a reasonable plan, although the level of success you have will depend on several factors such as how long you store the yeast under de-ionized water, at what temperature, the initial yeast health, and the strain. Storage under de-ionized water is still quite stressful for the yeast and viability could be very low depending on storage conditions. If the storage time is brief and cold, then it is less of an issue. The longer the storage time, the warmer the temperature, the more important it is to restore the yeast to health through a starter. If storage was very stressful, it might be necessary to start fresh.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #10 on: March 15, 2013, 09:45:33 AM »
Steven from Washington asks:
How beneficial is it to use filtered or bottled water rather then tap water when home brewing beer?

Thanks

Chris and Jamil answer:
Bottled water is rarely cost effective and it would only be beneficial if your tap water is somehow horrible. Even then, it is often better to just mix that tap water with some reverse osmosis or de-ionized water. If you do use bottled water, you still need to make sure to boil it to kill off any unwanted organisms. Unless your tap water is unusable, I would use filtered tap water. Keep in mind yeast need a broad spectrum of minerals for proper health and fermentation and tap water will generally have some of them. Using just distilled or reverse osmosis water without restoring those important mineral salts can result in poor yeast health and poor fermentation.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #11 on: March 15, 2013, 09:46:36 AM »
Kyle from Idaho asks:
My question is for Jamil. On the Jamil Show you talk about never using secondary fermentation because it's a waste of time and is just one more step that can infect and affect your beer. What is unclear to me is if I want to dry hop a beer do I do it in primary? I am fermenting in glass carboys and lack the ability to drop yeast out. Would I just wait until the majority of yeast has flocculated out and then dry hop? And will the yeast cake have any effect on the dry hopping process?

Thanks and cheers


Chris and Jamil answer:
We prefer not to transfer to another vessel unless there is a good reason to do so. Dry hopping is a good reason to transfer homebrew from one vessel to another if you cannot drop the yeast. One reason is that if you are harvesting yeast for re-pitching, you don’t want it full of hop material. And a second reason is that dry hopping with a large amount of yeast present may actually result in a slightly different flavor than dry hopping a beer that has dropped bright and had the yeast removed.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #12 on: March 15, 2013, 09:47:09 AM »
Leonard from Missouri asks:
There seems to be a discrepancy between the claims of liquid yeast producers. The claim they make is that their products are at adequate cell counts for pitching a 5gal batch, and that can differ from what we as homebrewers determine is the correct amount when we use a popular pitching rate calculator like Mr. Malty. For example if you have a very modest beer like a 1.040 OG ale, and you are using a very fresh pack of yeast at 97% viability, it says to use 1.5 packs of yeast. Even a small beer of 1.030 requires 1.1 vials/packs. Not trying to pit one expert against another here, but it would be interesting to discuss the topic. I make a lot of starters and it certainly requires more planning than if I were to have a truly pitchable amount of yeast. Also, is there something preventing White Labs from putting more yeast cells in their tubes?

Thanks


Chris and Jamil answer:
There are a couple of factors to take into account. One is that the yeast packages on the market strike a good balance between cell count and affordability. There is enough yeast in there to do a very good job of fermenting a typical beer and the price is still in a range that the market will accept. Even commercial breweries often purchase less than the 1 million cells per ml per plato, due to cost. They either propagate it up or brew with it as is and blend the beer into the next batch.

The reason some brewers may want to pitch at a higher rate is to achieve a different flavor profile from fermentation. In that case, they either make a starter, repitch yeast from a previous batch, or purchase more packages of yeast.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #13 on: March 15, 2013, 09:48:56 AM »
Greg in Virginia asks:
I use a stir plate for starters and get great results stepping up slurry amounts. Most all of the information available recommends good oxygen levels for starters as well as wort to build sterol reserves for cell walls. The question is whether I need to concentrate as heavily on wort oxygenation as the starter. How much benefit would there be in displacing the air in the starter vessel (Erlenmeyer flask) with pure O2, seal it with aluminum foil, and give it a vigorous stir cycle? After a short period of time, I would remove the foil and cover with a small beaker to allow my usual air transfer.

Additionally, I’ve reduced my starter OG to 1.025 - 1.028. I seem to get at least as much slurry as I did with gravities around 1.040. How low can the SOG go and still get good results in healthy, ready to go yeast?


Chris and Jamil answer:
If you are using a stir plate, then you most likely have adequate oxygen for healthy yeast growth. Additional oxygen may result in more yeast, but it may not as there may be some other factor that is limiting growth. Either way, there should be no harm from what you propose as long as the oxygen concentration does not become high enough to be toxic to the yeast.

I wouldn’t fret too much, as lower gravity starters can be better for yeast health. What you are finding in your higher gravity starter is that the yeast are using some of the sugars for growth and then just ferment the rest. This is why very large starters or low inoculation rates don’t grow much more yeast than properly sized starters. It isn’t a linear equation. In this case some factor other than sugar concentration is limiting growth.

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Re: Ask the Experts: Chris White & Jamil Zainasheff
« Reply #14 on: March 15, 2013, 09:49:38 AM »
Jeremy from Pennsylvania asks:
My question is as follows: I understand that one should control temperatures during active fermentation to not disturb the yeast through either rising or falling temperatures, or through a fluctuation of both. What I'm still a little confused about is how long should one control fermentation temperatures for. Do I control fermentation temperatures for active, conditioning, secondary phases, or all of the above?

I have only one temperature controller and one electronic heat blanket to keep temperatures warm enough in these colder winter temperatures (I also now have a fridge for the summer months). Please note that I live in South Philly and do all my fermenting in the basement where temperatures can go down to around 60ºF (or up to 75ºF in the summer). Most of my ale recipes, and the suggested yeast optimal temperature ranges, are within the 65ºF-70ºF degree range. Therefore, I've been shooting for a target fermentation at around 68ºF. If I'm doing successive batches, how long should I plan on using temperature control on any one actively fermenting carboy before I remove the controller and place it on the next batch? In addition, will any carboys that received active temp control be subject to any yeast "harm" during the conditioning phase once the controller has been removed?

In one calendar week over holiday break, I brewed three of Northern Brewers' extract kit batches and I did my first mead. I'm curious if perhaps I was a little too ambitious and I'm wondering if next time I should actively control fermentation temps all the way through one batch before moving onto the next.

Thanks for your help and insight!


Chris and Jamil answer:
Ideally you want to control your beer/fermentation temperature at all times. Every phase of fermentation and even beer storage is important. Allowing the temperature to freely rise or fall can sometimes work fine and at other times may cause issues with your beer. In general, rising temperatures during fermentation are better than falling temperatures, so if you can achieve that without the controller, then it would be less of an issue.