Foraged Yeast Pilot Batch Tasting

Not all of last month’s Farm Bière wort made its way into the fermentor. Instead, a small portion was diverted into separate mini-fermentors to evaluate a dozen new foraged yeast isolates.

These yeasts were initially foraged from Maine, Massachusetts, and New Hampshire during summer/fall 2016 with the help of Flynn. Once captured, slurry was sent to Jeff Mello at Bootleg Biology for isolation. Fast-forward four months and one dozen isolates arrived in the mail ready for evaluating!

Drawing inspiration from Jeffrey Crane’s Great EBY Brett Experiment, I created my own cheap and easy method for yeast strain evaluation. Like Crane, I utilized plastic PET water bottles as fermentors. Below is a brief overview of my method:

  1. Empty and sanitize twelve 700 ml plastic PET water bottles (I prefer Poland Spring Flip-Cap)
  2. Add ~500-600 ml of cooled, sterile wort to each sanitized bottle
  3. Pitch yeast isolates (I overpitched at ~5 billion cells)
  4. Attach cap and shake vigorously for 15 seconds
  5. Ferment at ambient temperature and vent cap every morning
  6. After ~3 weeks, cold crash water bottles for 24-36 hours
  7. Carefully transfer beer into a sanitized, CO2 purged, 500 ml plastic PET bottle (the amber soda kind)
  8. Quick force carbonate using a Carbonator Cap (5 blasts of 40 psi CO2, shaken then degassed)

Below are the condensed tasting notes, provided in 10-word highlights for each beer. They are described in order of preference.

Foraged yeast #4 – damp hay, tropical fruit, warm clove, pear esters, pencil shavings

Foraged yeast #5 – ruby red grapefruit juice, barn hay, black pepper, dry, tart

Foraged yeast #6 – banana esters, cracked black pepper, orange zest, salty, dry, tart

Foraged yeast #7 – banana esters, cedar saw dust, cracked black pepper, dry finish

Foraged yeast #8 – runts banana flavor, wet cardboard, fruit cocktail, lavender, cracked pepper

Foraged yeast #9 – Italian biscotti, vanilla cake, canned beans, sour raspberry, sweet finish

Foraged yeast #10 – sweaty horse blanket, boiled cabbage, tart, dry finish, Fantôme-esque

Foraged yeast #11 – canned beans, lemony acetic flavor, wonder bread crust, sweet finish

Foraged yeast #12 – urine, floral perfume, purple pez candy, cherry cough syrup, plastic

Foraged yeast #13 – spicy phenols, tart pink lemonade flavor, cantaloupe rind, canned beans

Foraged yeast #14 – canned bean juice, burnt rubber, dentist/medicinal, simultaneously tart/sweet

Foraged yeast #15 – canned beans, dirty wet socks, boiled cabbage, sweaty, tart finish

Overall, none of these foraged yeast isolates were particularly appealing. #4 was the most palatable, particularly due to its fruitiness, however I still prefer my house yeast strain (foraged yeast #1). Interestingly, many of the isolates displayed aggressive banana esters (think textbook Hefeweizen) or offensive canned bean flavors, neither of which were particularly enjoyable. #10 was toward the bottom of the list, but was very reminiscent of some of the flavors commonly found in Fantôme offerings.

Not all experiments pan out, but these mini-fermentations were still interesting and informative. I am looking forward to the next round of foraged yeast isolate pilot batches later this month!

foraged yeast pilot batch fermenting


4 Responses

  1. Are you planning to mix some of the yeast to see if it would give different results? Great blog by the way!

  2. Hi Gervais,

    I previously experimented with multi-cultured foraged yeast strains for Table Ale #1, with underwhelming results. I still have these isolates and may very well try to mix some of the strains for more analysis. Unfortunately, once you start mixing yeast you quickly get an exponential number of test batches!

    Additionally, I’ve thought about also using foraged yeast for secondary fermentation, since some are likely Brettanomyces. So much to do and so little time!

  3. Hey Andrew,

    Yeah, mixed fermentation can become quite a challenge with that much isolates!

    I was also wondering if you have seen a pattern between the source of the yeast and the tasting notes that they produce. In other words, do fruit yeast produce better beer than flower yeast for exemple?


  4. That is something I am hoping to be able to qualify with the yeast isolates. I’ve been keeping track of the source (fruit/flower/etc), terrain (countryside/city/coastal/vineyard/etc), temperature, and weather to see if there is any sort of correlation between those variables. I intend to have a future post recapping any relationships I find from my first three or four foraged yeast pilot batches in the coming month or so.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.