FAQ

This FAQ will be used to assist brewers in getting past first timer questions and over initial hurdles of brewing with bacteria and alternative yeast cultures. Please review this from time-to-time because it will be updated as often as necessary.

Quick Q&A

I have a question

Q: I am new. I want to learn more or have a question.

A: This wiki is a good place to search for answers, but you should also try to look up the answer to your question in the book "American Sour Beers" by Michael Tonsmeire. You can also do a Search in the Milk The Funk Facebook group to find threads about common subjects. Many answers can be found in these three resources. If it is not, post your question in Milk The Funk!

Is the wiki available in other languages?

Q: Is the wiki available in other languages, or can I translate the wiki into another language?

A: It would be great to translate the wiki into other languages, but the frequency of the changes to the wiki make this a difficult endeavor. Instead, we recommend using Google Translate. Go to the Google Translate webpage, and paste in the wiki url on the left hand box (http://www.milkthefunk.com/wiki), and then select the language to translate the wiki to on the right hand side. Click "Translate", and then browse the wiki in the selected language.

My beer looks infected

Q: My beer/starter/yeast slurry looks infected. What contaminated it and what do I do?

A: Usually, contaminated beers do not give favorable results. Exceptions occur rarely from wild contamination. If the contamination was from a cultured Brettanomyces that originated from equipment that was previously used for purposefully mixed fermentations, then the contaminated beer might turn out well because cultures from yeast labs are selected for their positive results. Otherwise, the chances of a wild contamination turning out good are very low. The best advice is to smell a sample of the beer, and if it does not smell good then dump the batch and brew a sour/funky beer on purpose (if the fermentation produces a fair amount of alcohol, it can be safely tasted after a month. See Safety for more information). If it smells good, the beer might be fine to package, however, even then your equipment will be exposed to the contaminating microbe(s) and there is no guarantee that the beer will continue to taste ok as it ages. Some contaminating microbes will slowly continue fermenting sugars in the beer and cause over-carbonation, bottle bombs, and increased off-flavors. So, the most pragmatic advice is to just dump it. If you choose to package the beer, keep the package cold so that the continued effects of the contamination are slowed as much as possible. Since the cost and time investments of a yeast starter/slurry are fairly low, it's best to just throw these out if they become infected and start over.

If you have space and time and want to simply learn what will happen with accidentally contaminated beer, then feel free to keep the beer in the fermenter and see how it evolves. Optionally, you could pitch Roeselare or some other mixed culture or Brett culture and see how it turns out after a few months. Brett can clean up some off flavors like diacetyl and acetaldehyde, but other off-flavors often won't be cleaned up by the Brett (like medicinal flavors and vomit/bile flavors). However, in the experience of most experienced sour beer brewers, this is not an efficient use of fermentation space. We recommend not wasting your time/fermentation space with accidental infections that show signs of off-flavors. Instead, use that space to brew an intentionally sour/funky beer and increase your chances of success.

As far as knowing what infected the beer based on what a pellicle looks like, the short answer is that you cannot confidently identify contaminating microbes based on what a pellicle or other visual signs look like to the naked eye. Microscopy can identify microbes to some degree (genus level), but DNA analysis is needed for species-level identification.

(Please note that questions regarding accidental infections for beers that were intended to be clean beers are considered off-topic in the MTF Facebook group due to the number of these posts we would receive otherwise.)

Is this mold

Q: Is this mold or a pellicle?

A: Mold is generally "fuzzy" or "hairy". Mold can also have color (green, red, black). See examples on our mold page to see the differences between pellicles and mold. Although many molds are not toxic, we recommend that beer that has been exposed to mold growth be dumped out because you can't be sure based only on what the mold looks like. Definitely dump any beer that has red or black mold growing in it.

I need a recipe

Q: I need a recipe for X style of beer.

A: The book "American Sour Beers" by Michael Tonsmeire has a great section on recipes. Also, we maintain a member-driven recipe database on Brewtoad: https://www.brewtoad.com/groups/milk-the-funk. We have a few recipes here as well.

Do I need separate equipment

Q: Do I need separate equipment for Brett/Pedio/Lacto beers?

A: There are many different opinions on this, but we will state here the best balance between practical and cautious advice. Brettanomyces can be cleaned and sanitized just like regular yeast, and if a brewery is using a saison yeast known for causing contamination issues like Saccharomyces cerevisiae var. diastaticus without contaminating other beers, then they will probably be successful using other wild yeast as well. Bacteria such as Pediococcus can be a little hardier, but they also still die from intense cleaning and sanitizing. Maintain a very good cleaning and sanitizing regimen (particularly if it involves heat treatment of the equipment at 185°F+ for 30 or 45 minutes), and you shouldn't need different fermenting vessels if they are glass, stainless steel, or kegging equipment. Plastic is prone to microscopic scratches and often can't withstand heat treatment, which can help bacteria survive cleaning/sanitizing regiments, so separate plastic fermenters for beers that have bacteria (Lactobacillus or Pediococcus) in them should be considered, but may not be necessary. Since cold side plastic equipment such as auto siphons and hosing are cheap, it is recommended to go ahead and get separate plastic racking equipment, airlocks, bungs, keg tap tubing lines, etc. Equipment that can be boiled can be re-used for clean and sour beers.

See Quality Assurance and Avoiding Cross Contamination for advice on brewing sours and clean beers together in a commercial brewery, as well as chapter 2, "Sanitation and safety" in "American Sour Beers" by Michael Tonesmeire.

Can I use a bucket

Q: Can I use a bucket to age sours or beers with Brettanomyces for extended periods of time?

A: HDPE buckets are more oxygen permeable, and with more oxygen comes the chances of acetic acid (vinegar) development. However, Brettanomyces also thrives from a little bit of oxygen. We have seen many reports of people using buckets successfully, even 2+ years and soleras. We recommend using a higher quality HDPE bucket with a lid that has a gasket that seals. Avoid plastic-on-plastic lids and screw on lids.

I have a question about pellicles

-See our pellicle page! Many questions can be answered there.

Q: I don't see a pellicle, is my beer OK?

A: The presence or lack of presence of a pellicle are not direct indicators of a good beer. A Pellicle forms when beer comes in contact with oxygen. Limit oxygen by taking samples only occasionally and if you have access to CO2, inject your fermentation vessel after pulling a sample. See pellicle for more information.

Q: How long does a pellicle take to form?

A: There are many variables and there is no one answer. It's all about the yeast and bacteria involved, O2 exposure, and time. Depending on all this, you may also never see a pellicle form. In the end, a pellicle only means there has been some exposure to an unknown amount of oxygen. Otherwise, pellicles have little meaning. See pellicle for more information.

Q: Do I need to wait for the pellicle to drop out before I package my beer?

A: The pellicle dropping out has no bearing on the readiness of the beer for packaging, nor the quality of the beer. Don't worry so much about pellicles! Instead, wait for a stabilized gravity for at least two months before packaging. See pellicle for more information.

Q: Is breaking the pellicle bad?

A: Although we recommend trying not to disturb the pellicle too much during sampling or moving the fermentation vessel, doing so isn't the end of the world. It will reform if oxygen is still present. If it happens, don't worry about it.

Q: I bottled a beer and now it has a pellicle. Is the beer ok?

A: Yes (assuming your beer intentionally had pellicle forming microbes). Pellicle formation is not uncommon in bottled beer. It is possible that the beer was exposed to some O2 during transfer/bottling, prompting pellicle formation. It is only an aesthetic issue and will go away over time, and you can induce this by disturbing it (gently shaking/inverting the bottle).

Q: Can I tell what microbes are in my beer based on what the pellicle and/or krausen looks like?

A: No. Identifying microorganisms down to the species level requires DNA analysis. See Pellicles for more explanations why.

Can I use dregs from _____

Q: Can I use dregs from brewery X?

A: If the beer is not pasteurized, you can. Check The Mad Fermentationist's dregs list.

Q: What about if the brewery uses killer wine strains at bottling time?

A: First off, killer wine strains only kill susceptible S. cerevisiae. They do not kill Brettanomyces. Secondly, if the commercial beer is sour then the chances of the wine yeast still being alive are slim. Anecdotally, brewers have had great success with dregs from breweries who bottle wine yeast (for example dregs from Hill Farmstead). See the Champagne Yeast in Commercial Dregs and Packaging and Re-yeasting page for more details on killer wine yeast strains.

For more information on using bottle dregs, check out this wiki page.

Q. Should I make a starter for the bottle dregs?

A: Generally, yes. If all you want is the Brettanomyces, and the bottle is relatively fresh (say less than 6 months old), then you don't really need a starter because pitching rates of Brettanomyces in secondary doesn't appear to have a large impact. If you want the lactic acid bacteria to be healthy, or the bottle is older than 6 months old, make a starter to ensure the dregs are viable. See Using Dregs for more information.

Why did my Lacto beer not sour

Q: My Lactobacillus based beer did not turn out sour or even the least bit tart. Why?

A: The biggest factor leading to lack of souring while using Lacto is due to the amount of hops in your recipe. Even as much as 2-3 IBU's will inhibit lactic acid production. Try brewing or kettle souring with no hops. See Wort Souring for more information.

Why did my Roeselare beer not sour

Q: I used Roeselare (or some other commercial mixed culture) and it did not sour yet. What do I do?

A: Sometimes Roeselare and other mixed cultures don't get the acidity that you might want. If it hasn't been a year yet, waiting longer may help, but sometimes it doesn't. If after a year the acidity is not high enough for you, try adding fruit such as cherries or raspberries (or even fresh wort). The fruit has various acids in it, and the sugar content will partially be turned into lactic acid by the surviving bacteria (the brewer's yeast will be dead after a year). Another option is to brew another beer and design it to be more sour. Brewing with 0-5 IBU and a very high mash temperature (158°F-160°F) is highly recommended for next time. Also, don't ferment with a clean yeast first and then add Roeselare in secondary; use Roeselare as the primary fermenter. Make sure the Roeselare package is fresh and was properly stored at refrigeration temperatures (lactic acid producing bacteria can die quickly if not stored right). For more information, see Roeselare and Mixed Fermentation.

Can I use extract

Q: I am not an all grain brewer, can I brew sour beer with extract?

A: Absolutely! Many of our members have made excellent sour beer with unhopped extract. We recommend trying the MTF Gose recipe, MTF Berliner Weisse recipe, or AmandaK's lambic-style extract recipe.

How much fruit do I add and when

Q: How much fruit do I add to a sour beer, and what methods do I use?

A: Generally it is best practice to add the fruit after the beer has finished aging, and allow the beer to age on the fruit for ~2 months for beers that contain Brettanomyces (2 weeks aging time is fine for kettle sours without living Brettanomyces). See the Sour Fruited Beer wiki page for amount suggestions and specific applications.

What happened to my head retention

Q: How can I improve head retention in sours?

A: Contrary to the belief that acid is the cause of poor head retention, it is actually probably more due to the degradation of head formation proteins by Lacto. See the Lacto Foam Degradation page to see what you can do about it.

Will Brett clean up off-flavors

Q: My beer has off-flavour _____; will it go away if I pitch Brettanomyces?

A: It depends on the off-flavor. Typical yeast character such as moderate amounts of diacetyl, banana, clove, and other esters will often be changed by Brett. However, many other flavors from things like fusel alcohols will not. Brett can esterify a small amount of Isovaleric Acid and Butyric Acid, but if the beer has high amounts of these then they are likely to stay. As the old saying goes, garbage in, garbage out. It's better to brew a clean beer and then add Brett, rather than try to recover a badly brewed beer by adding Brett.

Can I add Brett at bottling time

Q: Can I add Brett at bottling time to my beer fermented with only brewer's yeast?

A: Some people have gotten away with this, but unless you have experience with this, we don't recommend it. Brett will continue to ferment the residual sugars that Saccharomyces left behind in the bottle, and this could result in gushing or bottle bombs. Use bottles that are rated for higher pressures, such as Belgian bottles or sparkling wine bottles. Alternatively, you can rack to the beer into a fermentation vessel that you are comfortable exposing Brett to, add the Brett, and wait a few months for the gravity to stabilize.

See also Bottling With Brett.

My clean beer finished really dry, can I add Brett?

Q: I have a non-sour/non-funky "clean" beer that finished at a really low gravity (1.004-1.000). Is there enough sugar for Brett to do its thing?

A: Interestingly, Brettanomyces yeast does not need a lot of sugar in order to make a flavor impact. It can feed off of sugar sources that aren't being picked up by your hydrometer reading, and that weren't consumed by your regular brewer's yeast. Brett can also have an impact on the flavor just by metabolizing acids, esters, and phenols that were created by the initial brewer's yeast fermentation. Don't worry about how low the gravity is of your beer, Brett will find something. See the Brettanomyces page for more details.

Where did the mouse taint/Cherrios®/corn chip taste come from

Q: Q: Where did that Cheerios®/Cap'n Crunch®/Toasted cereal/corn chip flavor come from?

A: It can come from Brettanomyces or Lactobacillus. It generally appears after force carbonating in a keg and ages out in 2-3 months. See Tetrahydropyridine for details.

I used regular yeast and Brett, but my beer isn't sour

Q: I made a beer with Saccharomyces and Brettanomyces, but the beer isn't sour. What do I do?

A: Brett only makes a beer "funky" and fruity. It does not produce a lot of acidity. You need to brew a beer using lactic acid bacteria such as Lactobacillus or Pediococcus. Check out the Wort Souring and Mixed Fermentation pages.

Alternative Bacteria sources (yogurt, probiotics, etc.)

Q: Will this bacteria source work? Has anyone tried souring a beer with this? What temperature do I use?

A: Check out Alternative Bacteria Sources for a list of what some members have tried so far and their experiences.

Q: How many GoodBelly shots do I need, and do I need a starter?

A: Use only fresh GoodBelly that has been stored cold, and don't bother making a starter. 1-2 shots (or 8 ounces from a 32 oz carton) is enough for ~5 gallons of wort (~20 billion cells for 5 gallons). The mango is generally preferred as it contributes very little flavor, but others can be used as well.

Q: I used probiotics and my beer didn't sorry. What happened?

A: This generally happens due to one or more of these three reasons:

• The wort contained hops. Don't use hops in any form when souring with probiotics; hops can be added after souring has occurred if you choose. Probiotic strains of Lactobacillus tend to be very intolerant of hops.
• The temperature was too hot. L. plantarum for example prefers temperatures under 110°F/43°C. Higher temperatures might kill some species of Lactobacillus probiotics.
• The probiotics were expired or not stored properly. Probiotics are extremely shelf unstable, especially if not stored refrigerated (for both pill and liquid formats). If the viability of your probiotics is in question, make a starter and measure pH to see if they are acidifying your starter wort. See these general tips for more information.

What temperature do I kettle sour at

Q: I am making a kettle sour beer. What temperature do I hold at for my bacteria?

A: It depends on your species of Lactobacillus. For example, L. plantarum (both the Omega Labs OYL-605 Lacto blend and plantarum probiotics) tends to prefer 70-95°F, and temperatures of 110°F+ can kill it. Check out our recommendations on the Lacto Culture Chart, Alternative Bacteria Sources, and the Wort Souring pages.

I have a question about kettle souring

Q: How do I kettle sour, why did my kettle sour turn out bad, or is this mold?

A: There is a lot of poor information on the internet regarding kettle souring. We recommend starting with reading our detailed guide to kettle souring. We also recommend listening to our step by step instructions in our podcast interview with Adi Hastings from Omega Yeast labs.

In general, here are our biggest tips:

1. Don't use WLP677 for kettle souring, it's very slow and not meant for quick souring.
2. Don't use any hops until after the souring has finished. Even 1 IBU will inhibit a lot of Lacto strains.
3. Try to keep the souring time within 48 hours. Lacto leaves a lot of residual sugars, so the longer it is left the more potential there is for off-flavors from contaminations.
4. Sanitation is very important. Make sure the wort is boiled for at least a minute, and the sides of the boil kettle and lid are pasteurized/sanitized. Despite popular belief from many commercial brewers, using CO² is not necessary.
5. For your first kettle sours, we recommend using a Lactobacillus plantarum culture of some sort. For commercial cultures from yeast labs, see the Lactobacillus culture charts. For example, the Omega Yeast Labs OYL-605 has had a lot of success among MTF'ers. Yogurt and probiotics have also become a popular source for fast souring Lacto; see Alternative Bacteria Sources.
6. If your wort develops a krausen or significant CO² production, then you probably have a yeast contamination. Lacto does not compete well with yeast, so the sourness might not be as much as you wanted. Sloppy sanitation practices can lead to yeast contaminations, but this has also been known to come from yeast lab products themselves (it's hard to prove unless you look at the Lacto culture under a microscope using aseptic techniques).
7. Mold looks like patches of often fuzzy/hairy, off-white, green, red, or black growths on the surface of your beer. This can happen with kettle sours if your sanitation is not good enough. We recommend dumping kettle sours that have significant mold growth. See the Mold page for more details on the risks of mold.
8. If you can't find the answers to your questions from these resources, feel free to ask your question in the MTF Facebook group.
9. Listen to our podcast with Adi Hastings from Omega Yeast labs on kettle souring.

What pitching rate do I use for Lacto or Brett

Q: What pitching rate do I use for Lacto or Brett?

A: For Lacto, use around 500 mL to 1 liter starter volume for 5 gallons of wort. See the Lacto Starter Guide for more info. For Brett, it depends on if you are using Brett in secondary or primary. For secondary, no starter is necessary, although you may choose to make a starter anyway. For 100% Brettanomyces Fermentation lager pitching rates have been used with success. See the Brett Starter Guide for more information.

How do I maintain a culture

Q: How to I maintain a blend/a culture of ____?

A: The best way of storing your culture will vary depending on the organisms it contains and the resources you have available. See the pages for the relevant organisms for more information: Brettanomyces, Lactobacillus, Pediococcus, and re-using slurry from a mixed fermentation.

Do I need to use a secondary?

Q: When using Brett, do I need to get the beer off of the trub to avoid autolysis off-flavors?

A: Conventional wisdom is to remove the beer from the trub as soon as the beer is done fermenting, but this is not needed with beers that contain Brettanomyces yeast. Brett can "consume" the proteins and fatty acids that are released by dying yeast cells. Many brewers have reported storing sour beer on trub for many months and even multiple years without experiencing off-flavors from yeast autolysis. Read the Mixed Fermentation page for more details.

Can I repitch my sour yeast cake

Q: Can I repitch my sour yeast cake?

A: It is difficult to preserve the exact character of a blend, as the ratio of organisms will vary over time. Try repitching and see how you like the results. Pitching a fresh pitch of Saccharomyces yeast is a good idea.

Should I make a starter for commercial blend ____

Q: Should I make a starter for commercial blend ____?

A: You should if your commercial blend is nearing it's expiration date or wasn't handled properly, or if your batch size is much larger than the intended pitch rate. Otherwise a starter isn't necessary. It is often stated that making a starter may alter the proportions of the various organisms included in the blend. This may be true and it may or may not effect the flavor profile of the resulting beer but having an underpitch of unhealthy cells is a worse approach. Changing proportions is less likely with blends consisting of a single type of organism. While some yeast labs say not to make a starter for mixed cultures, others advise that it is perfectly fine. See advice from Yeast Bay as an example of how to make a starter for a commercial blend.

Q. My mixed culture from [X] yeast lab expired. Can I make a starter with it or use it?

A. Yes, make a starter with it. If the starter shows signs of fermentation, then the mixed culture can be used in a full batch of beer. Signs of fermentation include a drop in pH, gravity, or if those measurements are not possible, bubbles/CO² production and turbidity (cloudiness). If a full krausen does not form, then pitch an additional fresh package of brewer's yeast (a Belgian or saison strain is a good choice, but any strain will suffice). Mixed culture starters should go for about 7 days. See Mixed Culture Starters for more details.

When can I bottle/blend

Q: My beer is at 1.XXX---can I bottle it? Can I blend it?

A: Despite internet rumors, sour or mixed/Brett fermentation beers don't always end up at or below 1.000 final gravity (some can end up quite a few points above that, depending on the microbe selection and the wort composition). The best guide is long-term stability: if your gravity has remained stable between several readings, then your beer may be ready for packaging. However, since the different organisms involved in sour beer production grow at different rates, a beer that was stable over a short period may begin fermenting again. Ideally, you should look for stable gravity readings over a period of two months. When blending (especially with a non-sour beer such as a clean Saison), it is best to rest the blend in a fermenter for two months to make sure the gravity is stable. Don't assume that a low gravity clean beer such as a very dry Saison won't further attenuate once blended with a sour beer with Brett in it. If kegging instead of bottling, packaging before the final gravity is reached is ok since kegs can hold the additional pressure, and the carbonation can be adjusted. See the Packaging page for details on how to package your beer.

The other factor to consider is how does the beer taste? If it tastes good, and the gravity is stable, then you can package it. If the beer does not seem to have a mature flavor from the Brettanomyces and has off-flavors that need to age out, then feel free to age it longer. Some off-flavors will change even when bottled or kegged, but others (such as sulfur) will need to dissipate out of the beer slowly over time.

For more information on bottling, see the Packaging page.

I want to buy a ph meter

Q: I want to buy a pH meter. What is a good one to buy?

A: We recommend two tried and true models, the Hach Pocket Pro+ and the Milwaukee MW102. See PH Meter for more information.

I am traveling to _____, and want to visit some good breweries

Q: I am traveling to another state in the US. Any good recommendations on sour/funky breweries that I should visit?

A: Check out our MTF Member Map! Matt Miller also maintains a map for just this purpose. Click here to check it out. There are also other beer groups on Facebook and BeerAdvocate for getting recommendations.

Plastic tubs as coolships

Q: I saw this rectangular plastic tub. It has a similar shape to a coolship. Can/should I use it as a coolship?

A: We recommend against using shallow plastic tubs as coolships. Most plastics are not food grade. And those that are may not be food grade at boiling temperatures. Also, boil kettles provide sufficient cooling rates as long as outdoor temperatures are cold enough. If you are looking to mimic commercial processes, then a homebrew-sized boil kettle has a surface area to volume ratio more similar to commercial coolships and will have a cooling rate more comparable to commercial producers. See the coolship page for more info.

Only pitched Lacto and it produced a krausen or fermented more than expected

We have two great pages that help you brew your first kettle sour. See the Wort Souring page, and the Lacto Culture Charts!

Q: My Lacto-only pitch has a krausen, or the gravity dropped more than a few points. Is this a yeast infection?

A: Yes. Yeast contamination is the cause of a krausen or drop of more than .005 gravity points. Even heterofermentative bacteria do not produce more than a little bit of CO2 blow off. The yeast contamination could have come from not enough cleaning/sanitation. There have also been numerous reports of yeast contamination problems from popular yeast companies. We recommend buying Lacto cultures from one of the smaller yeast labs. See this page for details.

My beer mysteriously darkened!

Q: Why did my beer mysteriously darken (turned brown, black, or purple)? What causes that?

A: Food darkens in two ways: enzymatically with oxygen and phenols, or from maillard reactions from cooking. Darkening can occur from scorching the wort during wort production, or from using malt extract (which is darker from oxidation, or from production of the extract). If the darkening is not from the hot side wort production, then the browning was caused by oxidation in the fermentation vessel. Check out this Wikipedia page on food browning for an overview of enzymatic browning.

Gose

So, you're looking to brew a Gose (Gose-uh)? A Gose has become a favorite first time tart beer to brew. The dominant flavors in Gose include a lemon tartness, a herbal characteristic from coriander, and saltiness (the result of either local water sources or added salt). Gose beers typically do not have prominent hop bitterness, flavors, or aroma. The beers typically have a moderate alcohol content of 4 to 5% ABV. Our Milk The Funk Gose is a great place to start.

Sour Brown Ale or Lambic

There are many approaches to these styles of beer. They can be difficult styles to make with traditional processes. We recommend reading this wiki page and deciding on a method to use.

Berliner Weissbier

Berliner Weissbier, or Berliner Weisse, is a light, tart, low ABV, and refreshing beer that originated in Germany. It has a simple grain bill consisting of mostly pilsner and wheat (although other adjuncts such as chit malt are sometimes used). It's a great style to choose as a first sour beer, but it's also a great style to have on hand for any brewer (especially in the summer time), and is typically soured with Lactobacillus. Check out the Milk The Funk Berliner Weisse page for an easy recipe.