Monday, March 14, 2011

Maintaining Brett and Lacto Cultures

Brewing sour beer can get expensive with things like oak barrels, a second set of gear, and fruit. I think it is worth spending the extra money for anything that will improve the quality of the beer (especially when you consider how much top-shelf commercial sours can cost), but there are some areas where saving a few bucks doesn't mean sacrificing anything. One of those areas is maintaining your own microbial cultures, which not only saves money but also adds convenience and allows spontaneity when brewing sours.

Maintaining cultures is only something I would suggest if you brew sours regularly and know which strains have the right flavor contribution and fermentation characters for you. If you are just starting out brewing sour beers I’d suggest experimenting with different strains and seeing which ones work for your palate and brewing style before choosing which ones to maintain.

If you want to keep cultures on slants or streaked on agar plates that is an option. This method has never appealed to me because it takes special equipment (although not much) and time to build a culture back up to a pitchable quantity. If this is something you are interested in then I would suggest picking up a copy of Yeast by Jamil Zainasheff and Chris White. Even if you want to follow my “lazy” method, it might also be worth keeping plates so that you can start over with a known culture if the microbes in a starter die or mutate.

My two microbe starters, Brett B and Lacto.There are two options for keeping pitchable microbe starters on hand, you can either opt to propagate the individual strains separately or as a single mixed culture. Individual strains can be easier to maintain because each microbe has certain ideal conditions that may be at odds with another strain. Separate cultures also give you more flexibility if you want to make a beer with Brettanomyces, but not Lactobacillus (for example). Alternatively, maintaining a mixed “house” culture allows for more complexity because a huge variety of different strains can be maintained in a single vessel. There is no reason that you couldn't do both, or a hybrid method such as having a single culture with several strains of Brett, or both Lacto and Pedio.

I use growlers to store my cultures, although 750 ml bottles or one gallon glass jugs would work as well. No matter what vessel you select or what type of microbes you are growing make sure that you use a stopper and airlock to prevent oxygen and other microbes from getting into your culture.

I'm probably more lax with my sanitation then I should be, sanitizing the mouth of the fermenter (even flaming it as yeast ranchers do) would be the best process. You are afforded some protection compared to culturing brewer's yeast because the acid produced, high attenuation, and naturally funky character of the beers these cultures are used in will help to minimize the impact of any rogue strains.

I try to double the size of the cultures each time I feed them (something I picked up from keeping a sourdough starter). When I am ready to feed them I decant off enough of the spent wort so that when I double the volume I won’t risk the fermentation needing a blow off tube.

Brettanomyces – Brett is probably the easiest microbe to maintain because it is content slowly fermenting the complex dextrins in the wort. I feed my Brett B culture once every two months with ~1.030 wort (either malt extract or boiled down final runnings). I include 1/4 tsp of yeast nutrient (I like WYeast’s version) per quart. Once the starter wort is chilled add it and shake the culture to dissolve oxygen, which promote cell growth. I keep it at cool cellar temps to slow the growth.

Lactobacillus – Lacto likes simple sugars, so I use preservative free apple juice plus 1/4 tsp of yeast nutrient per quart. Apple juice comes pasteurized so it can be opened and added directly to the starter (although you could also dilute it up to 50%). Unlike yeast Lacto does not need oxygen to reproduce, but a small amount will not hurt it. I have read that some people decant their starters to avoid getting the malic acid from the juice into their beer, but the small amount has never caused a problem for me. Refrigerator temperatures are a good idea to slow their life cycle and keep them from dying between feedings. Adding some chalk can help to buffer against the lactic acid produced by the culture (Lacto doesn’t do well below pH ~3.8 per Vinnie).

Pediococcus – Haven't tried Pedio yet, but either malt or apple juice based starter with some yeast nutrients should work well for it. There is some debate over whether Pedio benefits from the presence of oxygen or not, although I think you are safest without since some sources say that it can produce acetic acid when given access to air. Your only real concern here is that, like Lactobacillus, it will produce a lot of lactic acid, so some chalk wouldn't be a bad idea (optimal pH for growth for P. damnosus is 5.0-5.5). I wouldn't worry if the culture smelled buttery since there is no Brett in there to clean up the diacetyl it produces.

Mixed Microbe Culture – A mixed culture should be kept in the refrigerator because the cold helps to retard the bacteria, preventing them from overwhelming the slower growing yeast. Starting with the slurry of a favorite batch is a good idea since you know how it is a good blend of microbes. Another is to keep an "everything" culture where you pitch in dregs from commercial and homebrew allowing the cultures that thrive to become dominant. Either way, I would still pitch fresh brewer’s yeast in addition to the culture to ensure a healthy primary fermentation.

For any type of culture it would be a good idea to feed it a few days before you want to use it just to make sure that the microbes are active before they are pitched. This is especially important if you are doing a 100% Brett fermentation or a similar technique where you are relying on the microbes to start fermenting quickly.

I asked Al Buck of East Coast Yeast for his opinion on this topic and it confirmed my feelings, "An easy thing to do is periodically decant off "old" starter media from the sediment and add fresh media w/ plenty of nutrients added - say every other month or so. Refrigerate afterwards until ready to use. What will happen over a couple of years is anyone's guess."

Both Al and Russian River have distributed cultures dried onto oak cubes/chips. This method allows for easier distribution of a culture, but they still need to be refreshed regularly. This method is a bit more time consuming since you’d need to start a fermentation from the chips, allow them to soak, and then dry on a rack every few months.

If you notice any issues with your cultures (no longer active, off flavor/aroma/appearance etc...) I would suggest dumping it and starting over from a fresh culture. The small cost of a new culture is dwarfed by the wasted money and effort of a poor batch.

Last summer I started a Berliner Weisse with my Lactobacillus starter. Coincidentally I just did an interview with James and Andy for Basic Brewing Radio on the style with some talk about keeping the culture going.

31 comments:

Adam said...

Another awesome post; the info is really great, and I look forward to putting it into practice once, as you suggest, I've brewed a few more sours and know which bugs I want to keep. Thanks again.

Dave Brush said...

Thanks for the write-up. It is good to know what your method is and how it has worked for you. I am one of those "yeast ranchers" and it works great for me, however it does not work so well with other microorganisms. For some reason that is beyond my limited knowledge (I have the yeast book mentioned btw) microbes other than saccharomyces c. do not grow very well on malt agar media. They apparently need specialized media which A) I do not know how to easily obtain, and/or B) is cost prohibitive compared to what I normally use for yeast. Therefore storing and propagating them in my regular manner does not work so well. I will definitely give this a go. I can definitely see how maintaining mixed cultures could be tricky as they certainly could easily get out of balance in favor of stronger bugs over time.

The Mad Fermentationist (Mike) said...

Interesting to know, I've only skimmed through Yeast.  Here is a post on Brettanomyces Project that might be helpful: Media Cultureablity of Brettanomyces Species

Mike said...

Thanks for the great post! I'm definitely going to try to keep some cultures of my own after reading this. How often do you feed your lacto culture?

The Mad Fermentationist (Mike) said...

I feed the Lacto about as often as the Brett, but that is the one to feed as frequently as possible.

Nick said...

Hi Mike. I have a question for you regarding lacto culturing:

I'm doing a lacto culture from the wyeast strain in order to try to build cell count for a couple of upcoming sour beer batches. Do you have any idea how long it takes for lacto cells to wake up and start multiplying? I've read that it's slower than saccharomyces yeasts, but don't really know how much slower. I'd rather not have to leave the culture for a month before using it.

The Mad Fermentationist (Mike) said...

Once Lacto gets going it is really quick at reproducing, but when I started my culture it took ~3 days to show signs of activity from the White Labs tube (the Wyeast packs have ~3X the cells). Once you see activity you are pretty much ready to go. Pedio and Brett are the ones that are much slower than brewer's yeast.

Good luck!

Nick said...

Awesome. I was starting to get concerned that I hadn't seen any activity yet, but if it takes a couple of days to get going, that makes sense.

I've also cobbled together a little box that I am keeping warm with a space heater, so I can try to keep the culture at ~85F.

Hopefully I won't burn my house down doing it.

Alex said...

I love this blog.

3 questions:
Why do you add yeast nutrient to a lacto starter?

If I have one white labs vial, how much apple juice is appropriate to start it with?

Would it benefit a lacto starter to keep it in the 95 - 100 degree range?

Thanks.

The Mad Fermentationist (Mike) said...

Like any growing organism Lacto needs trace nutrients/minerals that may not be found in malt extract and apple juice. There are specific tailored growth media that they use in labs, but I have no idea if their flavor would be compatible with the beer. I’m not sure it is necessary, but it certainly won’t hurt, especially for long term cell health.

Those tubes only contain about 2 billion cells, but Lacto grows incredibly quickly. I think you could easily start with .5 l if you wanted to. If you are worried start it smaller and then step it up.

If your goal is to make a starter and have it ready to pitch quickly, then 104-111 F is supposed to be the idea growth temperature for Lacto. If you are just holding the starter hot temperatures would cause it to run out of nutrients/sugars more rapidly.

Hope that helps, good luck!

Gonzo said...

You mention avoiding letting oxygen into the starter... does this mean that a stir-plate is a no-no for sour starters?

The Mad Fermentationist (Mike) said...

If you are growing a culture with just Brett (or a mixed culture of Brett and brewer's yeast)then a stir-plate is the perfect thing. However if it is a pure/mixed culture that includes bacteria I would skip the stir-plate.

Gonzo said...

Gotcha. Would using a carbonater cap to flush out oxygen w/ a 2 liter bottle be advised? I'm now a bit paranoid that my starter will turn to vinegar. I also had some oak chunks in the stater that might now be contaminated with bacteria. Hard to say, since I have a blend of Hannsens, Oud Beersel, 1809, and Petrus Bruin. Not sure if those would have bacteria or not. Thanks for the advice and awesome blog!

The Mad Fermentationist (Mike) said...

I don't think flushing with CO2 is necessary, although there are varying opinions on how sensitive Pedio is to oxygen. In terms of acetic acid, it takes a lot to make a substantial amount of vinegar, you just want to avoid leaving the starter open to the air.

There is certainly some bacteria in all of those beers as far as I'm aware, and odds are the lambics have some Acetobacter.

Amos said...

Thanks for sharing your experience here, I think I'm going to try this. How do you pitch from your culture when you want to inoculate some wort? Do you decant, pitch some slurry and then feed it again; or pitch some of the actual liquid?

The Mad Fermentationist (Mike) said...

Pitching the liquid from a bug starter is just fine. Good idea to give it a swirl first to get any of the microbes that have settled back into solution.

Anonymous said...

After a summer of grueling research, I've picked a few commercial brews (Girardin, Gueuze Fond Tradition, and Red Poppy) that I want to use to build a house culture from. I will probably be adding dregs from a new bottle every few weeks over the winter, with the goal of brewing my first sour beer early in the spring. Do I need to maintain separate cultures from each commercial example? I'm afraid if I pitch dregs into a starter that has already been active for a month or two, then the new bugs may never get a chance to grow. Thanks!

The Mad Fermentationist (Mike) said...

Sounds like some tough work!

I've had the best luck from pitching dregs directly into beers. Making separate starters makes sense if you are worried about the dregs. That way you can pick and choose what starter(s) turn out well, and pitch those. Start them small, step up, keep the oxygen low to limit acetic, and keep them cold to slow growth. The further in advance you make the starters the less representative they'll be of what was in the bottles.

Anonymous said...

In regards to the lacto, my worry is that by feeding and storing it only in apple juice, will it grow and develop and inability to process more complex sugars like those found in wort? What has been your experience? Does the apple juice make it lazy?

The Mad Fermentationist (Mike) said...

Over a couple generations, it shouldn't be an issue, but you are right that it could cause problems for long term storage. That is probably part of the reason that some breweries use a blend of wort and apple juice (that also cuts the IBUs of the wort as many pros just use the stream from another beer).

Anonymous said...

I have a question regarding lactobacillus starters and potential contamination (if that is possible).

Today, on day four of my lacto starter I noticed a rather large furrball resting on the bottom that resembles mold you might find growing on bread, appearing white and fuzzy.

I was planning on pitching into the lacto today but now I'm not sure if I should.

I started by pitching a rather fresh vile of Lacto D. from White Labs into 1000ml of cooled wort (75 degrees) with a gravity of 1.012 (attempting to match the gravity of the beer in the secondary, which currently has a healthy dose of Brettanomyces Brux). I also added 100ml of Santa Cruz brand organic apple juice to the wort prior to pitching to aid in feeding the bacteria.

I purchased a heat pad and played with the settings until I was able to keep the starter around 99-106 degrees and left it in the flask (no stirplate) for 4 days with foil and a rubber band acting as an airlock.

So my question is, did I contaminate it somehow? Should I dump it and start over? Or pitch it and hope for the best?

The Mad Fermentationist (Mike) said...

Mold needs oxygen, so what you are seeing is probably either turb or Lactobacillus. Especially so early on. Have you seen a krausen? CO2 production. Give it a swirl and see what happens.

Sadly the White Labs Lacto strain isn't great. It barely produces any acidity, even when nothing else is pitched, let alone in secondary with few sugars remaining. Actually most Lacto strains are going to have trouble in a beer that is already mostly fermented. You might be better off trying Peiococcus. It is more attenuative, so it can do more in a fermented beer.

In the future, I'd grow microbes in conditions that are best for growth (in this case, higher gravity), rather than trying to replicate the conditions the microbes will encounter in the beer.

panooq said...

Good info, thank you. Have seen people using molasses diluted in spring water for lactobacillus food, but I guess that would give it a darker flavor profile

Ryan said...

In this entire thread/blog/post there have been many mentions of apple juice, wort,nutrients, and even buffering for ph using some amount of chalk.

If you were develop a 1 recipe stop for culturing dregs, growing, and maintaining Lactobacillus - What would that recipe be? :)

The Mad Fermentationist (Mike) said...

Straight up wort with no hops and a small amount of yeast nutrient will works fine for any of these microbes/dregs. Certain strains of Lacto will grow better with the addition of simpler sugars in the form of apple juice, but it isn't required. I don't think buffering against the pH drop is necessary.

I had good luck this summer pressure-canning wort for easy dreg harvesting. Just a basic pale malt-based wort with a pinch of nutrient in each jar before processing.

Bekie & Dan said...

Mike,

Old thread, not sure if you still get post notifications, hopefully you do. Q for you: you state you use an airlock for your brett cultures... any reason why you go for an airlock? I can't find anything definitive (vs a foam stopper). I know brett produces acetic acid with oxygen, but if i'm just maintaining a culture, that seems to not be an issue. is it just a matter of better safe than sorry? or would oxygen over 2 months or so coming through a foam stopper be problematic in a way I am not thinking of? i'd think i'd want oxygen early on at least for better growth but maybe switch to an airlock after one week or something.

The Mad Fermentationist (Mike) said...

A foam stopped would be fine in the short term, but I'd worry about evaporation long term. Depends on how often you are using/feeding the culture.

Ross said...

Hey Mike,

When you say you store Brett cold are you saying fridge temp would work? I was assuming that would put them mostly to sleep. If you had to store your Brett culture at say 70 F would you feed it more often? I heard Chad Yakobson say he stores all his Brett room temp because his seems to die in the fridge.

The Mad Fermentationist (Mike) said...

I don't think I said I store Brett cold, just mixed cultures for short times. I've never noticed a large die-off from cold storage. The packs/tubes from yeast labs survive alright. It probably isn't ideal for long periods, and Brett really doesn't need to be fed all that often at room temperature anyway.

Ryan Mugele said...

Is Lactobacillus good long term cold storage? I am wanting to save the L. brevis as long as I can since it's a limited release. Seems like one that they should keep in rotation year round.

The Mad Fermentationist (Mike) said...

I wouldn't trust Lacto long-term without reculturing. I haven't tried to keep a strain going though, so I'd judge it on how quickly you see renewed activity. I'd keep it cold too.

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