August 31, 2018 by lpbrewer
Back when we started our journey to wrangle some wild local microorganisms the biggest question we faced was not if we could capture yeast, but if we could capture yeast that would make beer.
Now we find ourselves at a crucial juncture. We need to measure the attenuative properties of our yeast isolates to determine if any of the samples can ferment the more complex sugars in a malt based wort.
Yeast is everywhere in nature, living in places like flowers, fruit, and tree bark. It grows by converting sugars into the energy it needs to multiply, producing ethanol as one of its coveted byproducts. All yeast can consume simple sugars like sucrose, glucose, and fructose.
Over the centuries many cultures developed rich traditions of fermented food and beverage. Before humans discovered the organisms responsible and assigned them names, people had already modified these lifeforms by reusing material from pleasing results. Brewers yeast, with its ability to ferment the maltose that makes up the majority of wort sugars, has been under heavy selection pressure throughout the course of human history.
The packs of dried and liquid yeast available to modern homebrewers are the culmination of years of brewing study and science. We are fortunate to be able to choose from a variety of proven yeast strains (and other organisms) when crafting our recipes.
The beers produced from this panel would have no such advantage.
Baltibrewer Becky set to work this July, isolating and culturing up quantities of 6 strains of budding yeast. We decided the quickest way to find out what we had was conduct to a survey of 1 quart samples. The finished fermentations would be checked for specific gravity and pH drops. If any results were pleasing we’d bottle a 12 ounce sample. Yeast cakes would be saved for future use in larger batches.
Becky stepped up the cultures in the lab over the course of a few weeks and tested the samples for purity. On August 9th we met up with our yeast for a brewday!
For simplicity, we used Briess Light Dry Malt Extract and distilled water for our wort. We added a single charge of UK Sovereign hops for a bittering addition at 30 minutes.
|Original Gravity (Brix)||IBU||pH|
While the wort chilled we sanitized jars and airlocks. Given the lack of headspace in our tiny fermenters we added a few drops of Ferm-Cap-S as we portioned the wort 7 ways (one extra jar for a US-05 control). We pitched our samples and to our pleasure within a day or two we were off to the races!
Some jars showed more vigorous activity than others. We observed action in the airlocks of most. Given the homemade nature of our airlock fixture it was certainly possible our seals were not perfect. We decide to wait at least 2 weeks before checking the results. On August 29th, we gathered to investigate.
We processed the beers one at time. A single jar was briefly opened and a sanitized pipette used to remove liquid for a Brix reading. After we assed attenuation, we moved on to a quick smell evaluation. Any interesting results were bottled and the finished pH noted. The rest of the sample would be transferred a smaller container and stored cold.
It was time! What would we find!
To our amazement, 5 of 6 samples showed a significant drop in gravity and pH! The threat of commercial contamination loomed in our heads as we recorded tasting notes from the uncarbonated beer.
To our pallets the cultures produced distinct flavor profiles in the fermented products, some quite notable! Between the variety of results, the different levels of activity and flocculation, and the fact that one culture did not attenuate well at all, we’re very hopeful these fermented beers represent true isolates from wild captures and our coolship barrels!
|US-05||1.012 (6.6)||4.07||76.4%||5.25%||Did not save the yeast cake, tasted like a simple beer consistent with US-05|
|Caiti||1.013 (6.8)||4.42||75.1%||5.17%||Pleasing phenolic/spicy aroma, malty sweet taste|
|Riverside Park||1.015 (7.5)||4.43||70.9%||4.88%||Fruity aroma, clean flavor profile with low esters|
|1.015 (7.5)||4.40||70.9%||4.88%||Pleasing but more assertive phenolic/spicy aroma, mild phenols on the front, with a mild dry/tannin finish|
|Little Barrel||1.031 (11.2)||4.69||40.0%||2.80%||Did not bottle, smelled like baby diapers|
|1.016 (7.8)||4.42||69.0%||4.76%||Malty sweet aroma with phenols, sweet estery taste with more noticeable body|
|1.014 (7.2)||4.40||72.7%||5.01%||Cinnamon/earthy spice aroma, sweet and dry taste with a peculiar spicy phenol during the finish|
We buzzed with excitement as we cleaned, dreaming of things we could do with the saved samples! But as we looked to the future, we also reflected on the road to this point. Capturing this many strains of yeast that could complete a fermentation was somewhat unexpected. How did we end up here?
Was our capture medium with its low OG, IBU, and pH a sufficient filter for the small amount of malt friendly yeast to take hold? Did the large number of initial captures followed by aggressive triage of moldy and failed samples set us up for a better success rate once we got into the lab? Were our expectations set too low to begin with? We’ll continue to reflect on the project as we wait to taste the carbonated samples at our next meeting.
With fall on the horizon we are eager to continue our quest to make beers with native strains of Baltimore yeast. Cheers and happy homebrewing!
Tags: Baltibrew Yeast Capture
August 17, 2018 by lpbrewer
August 16, 2018 @ De Kleine Duivel
July 20, 2018 by lpbrewer
July 19, 2018 @ Nepenthe
July 11, 2018 by lpbrewer
This weekends sensory tasting panels have been postponed. New dates will be circulated once the event is rescheduled.
July 3, 2018 by lpbrewer
In April we distributed homemade yeast capture kits to the club at our monthly meeting. Our goal? To capture and isolate a strain of yeast native to Baltimore and use it to make a fermented beverage!
Members were eager to try their luck. The weather was poised to cooperate. Lows would bounce between 40 & 50 F for the next few weeks, a range said to be helpful when harvesting wild yeasts.
Things were looking up as we grabbed flowers from our backyards & local parks, swabbed out barrels used for coolshipped wort, or left our covered jars tucked safety outside. All that was left for us to do was to sit back and wait for the airlocks to start bubbling. So we waited!
Several members saw no activity at all. Others observed growth of mold or other non-yeast organisms.
As the reports came in it was clear that we were not going to see widespread examples of obvious & vigorous fermentation. So we began to triage the captures. Anything clearly growing mold was disposed of. The few samples that did report airlock activity were shipped off for early plating. The coolship barrel swabs proved more promising and were left to themselves for a month before streaking. When all was said and done the club selected 4 captures from a total of 16 trials:
While not the quantity we were hoping for it was nevertheless time to move this party into...
We're very grateful to Baltibrewer Becky who is doing the detail work on this project. Her first step, check the gravity (all samples stared at a Brix of 6.4 or 1.025 SG):
We found it interesting that two samples did not register a gravity drop. They both showed airlock activity, became turbid, and accumulated a layer of sediment on the bottom as activity slowed.
Did we incorrectly measure the first Brix reading? Was there really no decrease in gravity?
Cultures taken from the samples would tell us more. One drop of medium was transferred to individual Sabouraud Dextrose (Sab) plates. Plates were streaked for isolation and incubated in the dark at room temperature (approximately 68 degrees F). Within days they showed abundant growth.
Based on morphology the following organism were identified:
Success from failure? Possibly.
While the yeast strains are isolated and grown up, it's worth considering what we've accomplished and where we might go from here. The original plan was to isolate native organisms for use in a malt based fermented beverage. We now have at least 2 wild Baltimore yeasts on our plates and 3 more selected from barrels used after coolshipping. Two showed at least moderate attenuative properties in the capture media. Several did not.
Trials will tell us more but it is fair to suspect that these yeasts may not do well fermenting a malt based wort on their own. So is our plan still viable?
Michael Tonsmeire of The Mad Fermentationist blog and Sapwood Cellars (opening soon) stopped by our June meeting to share funky beers and talk about his brewing philosophies. One topic he spoke on was recognizing and embracing your individual strengths and scales.
As homebrewers it can be hard to make an Octoberfest that nails the style as well as commercial brewers. They have first pick of malts, laboratories to grow up strong & pure pitches of yeast, rigorous fermentation & packaging controls, and employees devoted entirely to quality control & sensory evaluation.
On the other hand we are not beholden to the demands of bulk production. This affords us flexibility. For example, we can experiment with secondary additions from local crops, using fruits that aren't grown in large enough quantities to be an option for commercial offerings. Just last month Mulberry Trees in our area started to yield ripe fruit. For anyone not familiar the mulberry is a delicious, mildly sweet & jammy tasting fruit that looks a lot like a blackberry.
Perhaps we won't end up with a yeast that can make a beer. But perhaps we will end up with several capable of producing local fruit wines and ciders! We will stick to our strengths as homebrewers and stay nimble. Cheers and happy brewing!
Tags: Baltibrew Yeast Capture