This guide will walk you through the process of capturing wild yeast and bacteria that’s naturally found pretty much everywhere in nature. While I used flowers as my yeast source, you can use fruit, tree bark, your beard or just the breeze to try and harvest your own special culture.
Be Smart and Safe
Before getting into this guide, I want to say a few words about being safe about this process. If one of your starters looks moldy, don’t even try to save it, just throw it away. If a white pellicle forms but it smells tart and citrusy, you probably have some lactic acid bacteria in there, which is great! If the starter smells rancid, dump it down the drain.
Lowering the pH of your starter wort will help prevent mold from being able to take place. Use your common sense and look at this experiment like you would any other beer you’ve brewed. If one of the starters looks or smells questionable, just get rid of it.
Note: This experiment was started on August 18, 2017 and was a few years old at the time of this posting. This is an exact transcription from my brew journal logs.
Process / Purpose
The purpose of this experiment is to capture wild yeast and bacteria found on flowers around Santa Fe. The first round of tests will consist of 8 mason jars with 175mL of 1.040 wort that has been soured to a pH of around 4. We’ll add one type of flower to each jar and watch it for signs of fermentation. Anything that grows mold will be discarded and considered a failure. We’re hoping to get something propagated into a large enough amount that we can brew a full batch of beer with it.
Ingredients / Equipment Used
- Ziptop bags for collecting flowers
- Dry malt extract (DME) for making the starter
- Yeast nutrient
- Lactic acid
- Mason jars with lids and rings
- 8oz jars for initial round of capture
- 32oz jars for propping up any viable captures
- pH meter (optional, but it comes in handy)
August 18, 2017 – Gathering flowers and starting the experiment
Here are the steps I took to gather flowers and get my cultures started
- I rode my mountain bike up into the Sangre de Cristo mountains here in Santa Fe with 5 ziplock bags and a marker. The goal was to collect wild flowers from different elevations and climates to add to the starter wort. In all, I collected 5 different kinds of flowers from the Winsor trail.
- Back home, I collected flowers from three different types of bushes in my yard for a total of 8 different starters.
- I brewed a 1.040 SG wort with 1500mL of water and 150g of dry malt extract plus a little bit of yeast nutrient.
- When the wort cooled I added enough lactic acid to drop the pH to around 4. This will help inhibit any mold or other unwanted bugs from taking over.
- I added one type of flower to each sanitized half pint mason jar and filled it with 175mL of wort. After filling it I very lightly put on a lid to keep out any dust but to let any gasses escape in the case of fermentation.
Here are photos of all the flowers collected for this experiment:
The following are photos of getting the flowers into their own jars of starter wort:
August 20, 2017 – Some mold
A fuzzy mold has formed in jars 3 and 6. No signs of activity in any of the other ones.
|Jar 1: No visible activity||Jar 2: No visible activity||Jar 4: No visible activity|
|Jar 5: No visible activity||Jar 7: No visible activity||Jar 8: No visible activity|
August 21, 2017 – Progress Update
Three of the jars ended up with mold so far. I’m not sure if it’s because the flowers weren’t fully submerged or the bad bacteria was simply stronger than anything that could be used for brewing. So far the only jar to show signs of a viable culture is #8 which formed a pellicle and smells tart.
|Jar 1: No visible activity||Jar 2: No visible activity|
|Jar 5: No visible activity||Jar 7: No visible activity||Jar 8: Pellicle with tart smell. Good so far!|
August 22, 2017 – Progress Update
Another couple of jars ended up with serious mold growth. So far we’re down to three jars that have some potential. I removed the flowers from jars #1 and #2 because there was some slight bubbling rising up around them and I didn’t want mold to take over. I’m not sure if I left the flowers in too long and already contaminated it with mold but we’ll see. Jar #8 is still the most promising. I removed the flower from this jar as well to hopefully prevent mold growth. The pellicle was growing very large when I opened the lid to check on it (see a pic in the #8 box below).
August 24, 2017 – Progress Update
I stepped up three of the jars (#1, 2 & 8) from 175mL to 500mL in quart mason jars. To do this, I prepared another starter worth with an OG around 1.040 but added too much lactic acid which brought the pH down to 3.6. We’ll see if that has any adverse effects. I used a brewing-only turkey baster to remove some of the sediment and liquid from each small jar and then added it to the bigger one. Between each one I washed the baster in bleach and then re-sanitized it to prevent any cross contamination.
August 27, 2017 – Progress Update
Out of the original 8 jars, two of them have progressed to something usable. Jar #1 has produced a lot of CO2 and foams quite a bit when swirled. Jar #8 has a really good pellicle growing on it and still smells tart. Jar #2 hasn’t shown any signs of activity since being stepped up. I think jar #1 will be good in some sort of Saison or Hefe. I’ll cold crash this soon and build up a larger starter and then pitch it into a one gallon test batch. I’m still not sure what to brew with the lacto in jar 8. Maybe I’ll use it for souring and then turn it into some kind of berliner by pitching either more yeast from Jar 1 or some normal brewers yeast.
August 28, 2017 – Progress Update
Jar #1 is being cold crashed right now. I’ll leave that in the refrigerator for 24 hours and then I’ll decant it and add it to a starter on a stir plate. Jar #8 is being left alone right now while I figure out what I want to do with it. Jar #2 went down the drain since it still hadn’t shown any signs of fermentation.
August 30, 2017 – Final step-up of Jar #1
I made up a 900mL starter with 90g of DME and a pinch of yeast nutrient. I then decanted the liquid off the cold crashed Jar #1 and added what was left to the starter and put it on the stir plate at a very low setting. For the first one gallon test batch of beer I’ll use 378g of DME total (50% pils and 50% wheat). I’ll very lightly hop it and boil for 30 minutes before chilling and pitching a portion of the starter.
August 31, 2017 – Jar #1 Starter
After signs of activity in the starter stopped, I sanitized two half pint mason jars and poured 175mL of the starter into each. These will be saved in the refrigerator for harvesting later. I’m currently cold crashing the remaining 600mL and will use this for the beer I described in yesterday’s update.
September 2, 2017 – BREW DAY! 1 gallon test batch of Jar 1
I brewed up a 1 gallon test batch for the wild yeast today. 190g Briess Bavarian Wheat DME, 190g Pilsen Light DME, 0.2oz hops from Rio en Medio 2016, pinch of yeast nutrient, 30 minute boil. OG was 1.039. Pitched the yeast at 74’F and will ferment for 2 weeks at 70’F, checking SG along the way.
September 14, 2017 – BREW DAY #2! 1 gallon test batch for Jar 8
I brewed up a 1 gallon test batch for the wild bacteria in Jar #8 today. 190g Briess Bavarian Wheat DME, 190g Pilsen Light DME, pinch of yeast nutrient, 5 minute boil. OG was 1.037. Pitched 90mL of the yeast/bacteria at 90’F and will let it sit for 1-3 days at which time I’ll test SG and pH and add US-05 to finish fermentation. Below is a picture of the pellicle prior to adding some to the wort. I think some yeast finally made its way in there as CO2 had formed in the jar.
September 19, 2017 – Fermentation Updates
The 1 gallon test batch from Jar #1 finally started fermenting after 1 week of daily swirling and higher ambient temps (up to low 80’s) have helped this. The FG on this beer was 1.006 and had a lot of phenolics similar to a saison. I was really happy with how this turned out!
For the 1 gallon test of Jar #8, I modified the yeast schedule slightly and simply delayed the US-05 pitch by a few hours. I dropped the temp to 68’F and added about 1/4 packet of US-05. Fermentation is still going but airlock activity has slowed and krausen has dropped quite a bit. I let this sit at 68 through the weekend and then moved it into my ferm closet for a couple months of aging on the wild lactic acid bacteria for a long term berliner weisse. The FG was 1.010 and the beer had an extremely clean citrusy tartness to it.
Final Update – 3rd Place in NHC Round 1!
I brewed a 3 gallon batch of berliner weisse using the Jar #8 lacto and US-05. I split the batch into 3 one gallon experiments and submitted a hibiscus rhubarb variant to NHC 2018. The beer placed 3rd in fruit/spice beer and moved on to nationals! Unfortunately it didn’t place there. I’m still really happy with a beer that was soured from natural bacteria obtained from a flower in my front yard was able to make it to round 2 at NHC.
Changes for next time
I copied this guide exactly as I wrote it in my journal, but I would recommend only leaving the flowers/fruit in your starter wort for about 24 hours. I left them in for about 72 hours which I think contributed to mold growth in several of the starter jars. The parts of the flowers that weren’t submerged were prime candidates for mold formation.
There isn’t a lot that goes into capturing your own wild yeast and bacteria. As long as you have a basic understanding of sanitary brewing, you can easily try your hand at harvesting your own culture.
Out of the 8 jars I started with, two went on to produce excellent beers while the other six failed. I was really surprised to even get anything remotely drinkable, let alone to turn it into something that scored well at National Homebrew Competition.