Brewers make wort, yeast make beer.

If you have been homebrewing for even a short amount of time you have probably heard that statement. As much as we would like to think that we are in control, it is our microscopic little friends that determine the quality of our batch; brewers are little more than glorified yeast wranglers. Thus, when fellow homebrewers ask me what they can do to improve the quality of their beer the first thing I always tell them is: “make a yeast starter.” Proper amounts of healthy, happy yeast make delicious beer free from off-flavors; simple as that.

Time to let you in on a little secret: yeast are not the only things that make beer! Myriad organisms such as Brettanomyces , wild Saccharomyces, Pediococcus, and Lactobacillus will happily feast upon the wort you just created and leave you with beer (and those are just the organisms that produce favorable characteristics). Indeed, it is these organisms that folks interested in making sour or funky beers will harness to produce the character they are looking for. However, whether you are making a clean beer with “regular” yeast or a sour/funky beer with these other organisms, one thing remains the same: proper amounts of healthy, happy <insert organism(s) of choice> make delicious beer free from off-flavors. When folks tell me their sour mashes go bad I liken it to folks saying their regular beers went bad, only to find out they pitched a single vial of old yeast into 1.090 OG wort at 95ºF. A little bit of preparation practically guarantees a successful souring; whatever your organism of choice is, make a starter!

If you have been following along with Year of the Sour Mash you will know we are primarily interested in the fast, clean souring of Lactobacillus to sour our mash/wort. Whether you are pitching a pure culture of Lactobacillus or growing a wild culture from grains, I have created this Lactobacillus starter guide to help you propagate the quantities needed to ensure your beer sours cleanly.

Supplies

(Images/links lead to MoreBeer! where you can purchase them if you need)

If you have ever made a yeast starter, with a few small exceptions you likely already have everything you need–you do not even need a stir plate!

Erlenmeyer Flask (2000 ml) – If you do not use an Erlenmeyer flask for your starters, now is a great time to get one. I boil my wort in the flask, chill, then pitch my organisms. Just make sure the flask is borosilicate (Pyrex).

Universal Stopper – This is one of the rare times I would advocate an airlock for a starter, but Lactobacillus is anaerobic so we want to keep oxygen out while we grow them. This stopper should fit 500 ml to 2000 ml flasks.

Airlock – For the stopper, just use whatever you have.

Dried Malt Extract – You will need approximately 200 g of DME to make the starter wort. It is not any different than the starter wort you might make for a “regular” starter.

2 cups uncrushed base malt – The source of wild Lactobacillus, malt is literally crawling with it. You can use whatever malt you want, but regular ol’ 2-Row is the cheapest. My friend Peter is adamant about using rye malt for inoculation, so it is your call on what to use.

Lactic Acid 88% – We will be using this to lower the pH of our starter. It is also great to have on-hand for mash adjustments.

Yeast Nutrient – I always add a pinch of yeast nutrient in my starters to ensure my organisms are maximally healthy after propagation.

Carbonated Water – I use this to top off my flask to fill up headspace and purge oxygen. Nothing fancy, should list “Water, CO2” as ingredients.

Reptile Heater Pad – I use this in my fermentation fridge to turn the fridge into an insulated hot-box. I can keep the starter at an even ~115ºF using this pad.

– I use this in my fermentation fridge to turn the fridge into an insulated hot-box. I can keep the starter at an even ~115ºF using this pad.

Instructions

My instructions are for 5 gallons of packaged beer with 5.5 gallons going into the fermentor; if you brew 10 gallon batches just double my recommendations. I am also of the opinion that it is hard to over-pitch either yeast or bacteria, so feel free to cut my recommendations in half. Just remember: the more you pitch, the faster and cleaner it sours 🙂

Wild Lactobacillus

I am a fan of “rolling the dice” with wild strains when it comes to souring with Lactobacillus–there is an amazing spectrum of character available “for free” that you cannot find from commercial pitches–so this is the method I employ the most. We will be culturing the natural Lactobacillus from the grains, so the key is dropping the pH as quickly as you can to impede other organisms from taking hold; trivial to accomplish in a starter with the 88% lactic acid. When paired with my sour mashing method I have never had a souring go bad.

Cultured Lactobacillus

Growing a pure batch of cultured Lactobacillus is not too different than growing a pure batch of cultured Saccharomyces and uses the same time scale as the wild Lactobacillus instructions. The good news is that many pure cultures can be propagated at room temperature. Please refer to the Milk the Funk wiki article on Lactobacillus for precise recommendations for your strain. This is also the method I would use when pitching yogurt or probiotics as my Lactobacillus source.

Create a starter with 200 g DME, 2L of filtered tap water, and a pinch of yeast nutrient. Chill starter to temperature listed in the Milk the Funk wiki. Pitch vial of bacteria. Top flask off with carbonated water. Plug flask with airlock*.

* L. brevis actually benefits from oxygen on a stir plate. If culturing L. brevis, cover with aluminum foil or foam stopper and stir it up. 2-3 days later, pitch directly into mash/wort.

Easy peasy! When pitching a Lactobacillus starter into my sour mash/wort I have seen the pH reach 3.3 in as little as 24 hours, so be sure you keep a close eye on pH levels and be ready to finish the boil (or whatever your next steps are) as soon as the mash/wort is where you want it.

Happy souring!

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