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Reharvesting Yeast

Written by Guest Blogger


Posted on August 10 2016

One of my favourite things about homebrewing is the ability to create essentially any style of beer imaginable. Sometimes it’s a creative process — “What if I put figs in a brown ale?” — but other times you try a beer and think, “I just want to make exactly that!” This happened most recently when I cracked open a bottle of Amber Ale from Bell’s Brewery, a craft brewery based out of Michigan.

Cloning Bell’s Amber Ale is a little more tricky than some other beers because the brewery uses a proprietary yeast strain. Luckily, Bell’s beer is bottle conditioned, meaning that in each bottle there is a (relatively) small amount of perfectly viable yeast just waiting to be reharvested by an admiring homebrewer.

Given such a tasty brew and the added difficulty of acquiring it in Ontario, I decided to reharvest the yeast and clone it. Here’s an unscientific guide to capturing yeast from a bottle of beer.

First choose an unfiltered beer from which you would like to harvest yeast. Be aware that some breweries bottle with a different strain of yeast than the one used for fermentation (send the brewer an email if you’re unsure). 

Also keep in mind that sanitation is especially important while reharvesting yeast because you want to obtain as pure a sample as possible, and scale it up without any other critters coming along for the ride.

Start by mixing about 15 grams of dry malt extract (DME) in around 300 ml of water and boil for 15 minutes. After letting that cool down, crack open your beer, flame the lip of the bottle with a lighter, and pour yourself a glass, leaving about 2 cm of beer behind in the bottle. Swirl up the dregs and pour your cooled wert through a well-sanitized funnel into the bottle to about one third full. Cover with sanitized tinfoil.

After a few days you should notice some bubbling in the bottle and once that settles prepare a new starter, this time about 1 litre in volume with 90 grams of DME. (I like to boil my starter solution inside an erlenmeyer flask, which is a good way to sterilize the vessel.) Remove tinfoil and again flame the lip of the bottle. Swirl it up and pour it into the new (cooled) starter. Repeat this process twice, 2-3 days between, each time decanting the previous starter and pouring it into one with a volume increased by 500 ml.

Step  Volume Amount of DME Time (approx.)
1 ~100 ml in the bottle 15 grams for 300 ml  4-5 days
2 1 litre 90 grams 3 days
3 1.5 litres 150 grams 3 days
4 2 litres 200 grams 2 days
5 (if needed) 2 litres 200 grams 2 days

By the end you should have a 2 litre starter of reharvested yeast ready to be pitched into your next batch of beer.

And for those of you curious about the Amber Ale, here’s the recipe I settled on.

Bell’s Amber Ale Clone

Volume: 19 L
Yeast: Reharvested Bell’s yeast
Water: Kitchener tap water (treated with campden tablets)
OG: 1.056 FG: 1.012
ABV: 5.8
IBU 35-40 SRM: 10-13
Fermentation: 2 weeks at 20*C

3.73 kg Canadian 2-row
0.68 kg Crystal 40
0.44 kg Munich malt
0.17 kg Crystal 110
0.18 kg Acidulated malt
½ tsp Yeast nutrient 10 min.
½ Whirlfloc tablet 10 min.
14 g Fuggle (4.1% alpha acids) 40 min.
14 g Cascade (6.9% alpha acids) 40 min.
14 g Fuggle 20 min.
14 g Cascade 20 min.
14 g Fuggle 10 min.
14 g Cascade 10 min.
14 g Fuggle 5 min.
14 g Cascade 5 min.

Author Bio: Seth lives, works, and writes in Kitchener. He has been homebrewing for about four years and loves sharing the fruits of his hobby with anyone who shows the slightest interest. 



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