Cultivating bottle dregs

UPDATE NOTE: This post describes a failed attempt at cultivating bottle dregs. If you’ve found this page looking for information on how to cultivate bottle dregs for pitching into beer wort, thank you for reading but please do not follow my process below. It didn’t work for me, as you can read in my follow-up here.

After deciding to brew a Bronze Age-inspired fig beer, I quickly went to work on the recipe in the hopes of brewing it on Monday (which I have off from my day job). It’ll be a 1-gallon experiment batch, with 2-row barley and rauch malt for that Bronze Age kiln-smoked flavor. Bitter orange peel will feature as a flavoring, and I haven’t decided yet whether it’ll have minimal hops or none. Honey and figs will round out the flavor and provide additional fermentable sugar. For yeast, I plan to cultivate a 2-step starter from the dregs in a bottle of Dogfish Head Midas Touch.

I’ve never cultivated a starter from bottle dregs before. Why now, and why Midas Touch? One usually hears about brewers cultivating dregs from sour beers like Orval to harvest the unique blend of Brett and bacteria strains that make those beers special, as described in this blog entry from TheMadFermentationist.com. But it should work with clean Saccharomyces as well.

I’m not sure what kind of yeast is used to ferment Midas Touch, though clone recipes online call for Trappist ale strains. I don’t even know if the yeast Dogfish Head bottles Midas Touch on is the same as the yeast that ferments it – many breweries use different yeasts for bottle conditioning. So my decision to use Midas Touch dregs was less about capturing a particular unique yeast than it was about superstition.

9 out of 10 prehistoric shamans agree: Consume your totem’s essence to gain its power.

Midas Touch is one of Dogfish Head’s “ancient ales” and is based on chemical analysis of bronze vessels found in Gordion in Central Turkey – roughly the same part of the world as Cyprus, where my fig beer has its inspirational roots. I thought the dregs might be a good luck charm for my first foray into ancient brewing: a little piece of the magic from Sam Calagione and Dr. Patrick McGovern, two of the high priests of modern ancient ale reproduction. But really, the main reason I did it was because it sounded like fun and I’ve never done it before.

I made a first-step starter wort of 200 milliliters to bring the bottle yeast back from the dead. When that ferments out, I’ll “step it up” to a second starter of 500 mL. For a full 5-gallon batch I’d continue stepping up to 2 liters, but for a 1-gallon batch, 500 mL should suffice.

I scaled down my usual starter process as well as I could, realizing it’s okay if some the math isn’t exact in a wild-shot experiment. I dissolved 15 grams of extra light dry malt extract in 200 mL of boiling water. Usually I use 1 gram per 10 milliliters, but I’m hoping the lower OG starter will give a little advantage to sleepy yeast.

I also added 3/32 of a teaspoon of yeast nutrient. While that sounds like a strange fraction to use, it’s simply one each of the “pinch” and “smidgen” measuring spoons (or 3 “smidgens”) available at specialty kitchen stores. Those little spoons aren’t all that useful on a day-to-day basis, but I keep them around just for tiny measurements like this. For the record, an exact scaling of my usual 1/2 teaspoon nutrient per liter of starter would have been 1/10 teaspoon.

It was almost too small to boil on the stovetop.

5 minutes of boiling reduced the starter volume more than expected, so after I cooled it and transferred to a sanitized pint glass, I topped off with pre-boiled water and chilled in the freezer to an acceptable pitching temperature of 84°F. I roused the yeast in the last half-inch of a bottle of Midas Touch (which I had already poured into a glass and was drinking) and pitched it.

Ready for the stir plate.