Tree Bark Yeast, Part 1

Introduction
Wild yeasts are all around us. To think that waaaaaay back when, sugary liquids just "magically" fermented on their own, people had no idea that these tiny single celled microorganisms called yeast were actually doing all of the work.

Where do these wild yeasts exist? They are floating around the air, living on all sorts of things, and even inside things, like wasps. After random internet searching I stumbled upon an article stating that a cousin of Sacchromyces Cerevisiae, S. Paradoxus actually lives on the bark of Oak Trees. Oregon happens to have its own species of Oak, Quercus Garryana. And one person somehow got a pitch of this yeast and made a beer out of it with some possibly promising results. So why not try to catch my own, and or something else along the way? Because finding an awesome usable wild yeast, is like instant bragging points in the homebrewing world right? Kind of like Beer Cred?

This post is Part 1 of hopefully a 3 Part series. Part 2 will take a hopefully usable strain, and isolate that strain, then grow it up into a sizable pitch for a 1 gallon beer ferment. Part 3 will be using that pitch to make the 1 gallon batch of beer.

Objective
To catch a usable strain of yeast off of a tree, and use sensory analysis to determine if the yeast is USABLE.

Prediction
I will catch a USABLE strain of yeast off of a tree that will eventually ferment a delicious beer.

Materials Needed
DME
Water
Yeast Nutrient
Scraping tool
Vials
Sanitizer solution
Heating pad

Procedure
Finding wild yeast
According to the article above, wild yeast like to live in the bark of trees or in the "extracant" of trees, aka, liquid matter that a tree will release, like pine tree sap. Here in Oregon we have primarily decidious, coniferous and fruit trees scattered all over the place. So finding a tree isn't hard, its understanding WHERE on the tree to look for a location.

I already decided to look at an oak tree, but I also wanted to try pine tree sap and one other tree type to get 3 totally different samples.

Capturing wild yeast
For the oak tree,  and for everyone I examined, the bark was pretty uniform, and even if there was a rough spot, I didn't notice any extracant. So I took a knife and carved a hole in it and grabbed small samples of every layer of bark until I hit a nice depth.

For the pine tree, I found one that had emitted pine sap pretty recently, and also awhile ago. I grabbed small samples of old and new.

For the 3rd, this was a total awesome surprise: I have a 20-30 year old (estimated) apple tree in our back yard. A large branch was cut off some years ago and the cut location scabbed over. It had just been raining (welcome to Oregon!) and I noticed yellow droplets on this scab. I also noticed a number of fruit flies buzzing around this very location. Fruit flies = sugar! Sugar = yeast living near! So I scraped up this yellow droplet material and some "stuff" growing on the scab as my sample. I have high hopes for this one.

Fermenting with wild yeast
To get my samples to actually ferment something, I made up a 1.040 sample of wort using water, DME, and a pinch of yeast nutrient. I boiled the solution, chilled it and filled up used White Labs vials that had been cleaned and sanitized. Each sample was added to its own vial of wort. All three samples will sit in a glass to remain upright and this all will be placed on a heating pad and covered to maintain a constant 72* temperature to allow favorable fermentation temperatures.

I am going to give each sample 10-14 days to do their thing and grow a large enough sample that I can throw it onto a stir plate if the sample it fermented smells good or it will get tossed if it ferments something that smells like either poo, puke, or garbage.

Sensory analysis will be done in the morning and evening to record the appearance and aroma of each sample. For appearance, bubbles forming, cloudiness, and a hissing of air when opening a vial will determine how the ferment is going. For aroma, looking for a fruity, bubblegum, and other favorable smells will be good, whereas poo, puke, and garbage smells will tell if the ferment is going badly.

Observations

			Appearance			Aroma
Date	Time	Apple Tree Scraping	Oak Tree Bark	Pine Tree Sap	Apple Tree	Oak Tree	Pine Tree
11/28/16	PM	Clear wort, some specs of material, settled wort trub	Clear Wort, with some bubbles from agitation, settled wort trub, oak tree stuff	clear wort, settled wort trub, pine sap	Wort	Wort	Wort with pine from sap
11/29/16	AM	bubbles starting to form	same	same	doesn't smell like wort anymore, clearly something is fermenting	Still wort smelling	still wort smelling with the pine sap
11/29/16	PM	more bubbles, slight cloud	same	same	smells like Brett	same	same
11/30/16	AM	very cloudy	First Signs of Fermentation, some bubbles	First Signs of Fermentation, some bubbles	stronger brett funk, some cheese, corn	neutral smell	wort smell is gone, neutral smell with pine
11/30/16	PM	still very cloudy	Getting cloudy, but not as cloudy as pine	Getting cloudy	super strong brett	some brett smell forming	some brett smell forming, with pine from sap
12/1/16	Midday	no change	cloudier than pine, lots of bubbling activity. Large hiss from opening cap	no change, doesn't look like much is happening	still super cheesy and bretty	gaining more cheese and bretty, getting similar to apple tree	no change
12/2/16	AM	More bubbles, still as cloudy, pellicle has started to form	LOTS of activity. Large hiss when opening, causing debris @ bottom to shoot to the top, very cloudy	maybe slightly cloudy? no signs of bubbles	not as cheesy, but still has brett smell. Calmed way down in terms of smell intensity	smooth out a bit in terms of smell intensity	no change
12/3/16	AM	hiss when opening; pellicle is getting thicker; still as cloudy	TONS of activity! opened up to HUGE hiss and then a layer of foam wanted to shoot out of the vial! stirred everything up pretty violently. What a krausen!	no change	slight hint of spice; but other wise still the same level of cheese and brett	slight spice, very very slight fruit, cheesiness has disippated some; brettyness has balanced	no change
12/4/16	PM	half the pellicle disappeared; still as cloudy	still a HUGE hiss and krausen and violent mixing upon opening vial, but not as huge as 12/3/16	no change	cheese has disappated; mostly bretty smell	clove and cinnamon are coming out the strongest with a slight fruit; still some bretty character	no change
12/5/16	Mid Day	pellicle is still there, but co2 bubbles have become trapped in the pellicle; still sight hiss when opening	eruption intensity has dropped by 1/2	mold is starting to grow; still no CO2 activity	same	same	no change
12/6/16	AM	same	eruption is a tiny fraction of the max a few days ago. Still some outgassing; things are calming down for sure; peak was reached on 12/3/16	no change	same	more bubblegum is emerging	same
12/7/16	Mid Day	pellice dropped	no activity of bubbles when opening; barely a hiss when opening	more mold	same; still brett characteristic	still bubblegum	same
12/8/16	Mid Day	no change	same	same	same	same	same
12/9/16	AM	same	pellicle is starting to form	same	same	same	same

Analysis
Of all three experiments, only the pine tree sap was a total bust. Nothing really happened. Is there some form of antimicrobial property that lives on pine tree saps that inhibits yeast from growing on it?

For the other two, apple tree and oak tree, both did something, and enough to pursue further.

For the apple tree, it took off the quickest, but didn't really reach an explosive level of activity. Its smell was more on the brett side of the spectrum. On the other hand, the oak tree took a little bit to get going, but once it got going, IT GOT GOING! In terms of activity, on 12/3/16 when I opened to inspect I had to quickly close it back up or else lose half the volume to a foam-over. Thats a good sign of fermentation! The oak tree's smell started off bretty and cheesy much like the apple tree, but eventually the brett and cheese vanished, only to be replaced by spice and fruit and bubblegum, a possible sign of a Saccharomyces strain.

Conclusion
Based upon sensory analysis, my conclusions are going to be more like predictions for part 2 of this experiment. I have no definitive way (at the moment of writing this) that the apple tree strain is a Brettanyomyces strain, and the oak tree sample is a Saccharomyces strain.

But because Brett tends to be more cheesy, barn-yardy, horse-blankety, and the apple tree smells like all of those things, that is why I am "think" it is a Brett strain. And because Saccharomyces strains can be spicy, fruity, and bubblegummy, I "think" the oak tree strain is a Sacch strain. Also because of my research that S. Paradoxus grows on Oak trees, perhaps I did catch S. Paradoxus on my first attempt?

Future experiments will tell...