Fermentis Safale K-97 Yeast review

Fermentis K97 is an uncommon strain in the homebrewing community around the world and not much information is available on the internet. For these reasons, I decided to write a general review on this strain taking inputs from homebrewers in Pune.


For guidelines, I have taken some information from the company website.

Character: German ale yeast selected for its ability to form a large firm head when fermenting. Suitable to brew ales with low esters and can be used for Belgian type wheat beers. Its lower attenuation profile gives beers with a good length on the palate.

Fermentation Temperature: 12-25°C (53.6-77°F) ideally 15-20°C (59-68°F)

In this review I will be discussing about the following points.

  • Apparent Attenuation
  • Temperature range
  • Time taken for High Krausen
  • Primary Fermentation
  • Bottle carbonation and Conditioning
  • Flavor Contribution 


Apparent Attenuation

Wort of different OGs ranging from 1.042 - 1.064 were subjected to fermentation by this yeast. Apparent attenuation observed was between 75 - 81%.
Offcourse the fermentability depends on mash temperature, use of specialty malts and adjuncts etc. For a supposedly Kolsch strain, this apparent attenuation is pretty high.

Temperature Range

Most of us fermented it at 17C which is within the recommended range. No experiments done here.

Time taken for High Krausen

We all made starters for about 48 hours and pitched the yeast after decanting. Now, the time taken for high krausen to form was very variable. Few of us observed high krausen after 8 hours, while others noticed it after almost 14 hours. There are various theories for this but the important point to remember is that you need not worry even if it takes about 14 hours before you see a nice healthy krausen.
The characteristic feature of this yeast is that it forms a huge, thick krausen that lasts for a good 10-14 days. You may notice that primary fermentation is done in 7 - 9 days, but the krausen will remain. Most of us had to actually cold crash primary to forcibly settle the yeast.
Note: Leave a good 4 inches of head-space in your primary to be safe from a yeast blowout.

Primary Fermentation

As mentioned above, primary fermentation was done within 7 to 9 days but we had to wait for yeast to clear up and settle down. Primary fermentation is said to be complete when you get a stable FG reading for a minimum of 3 consecutive days.
Sedimentation and flocculation is good.

Bottle Carbonation and Conditioning

We recommend 3.2 - 3.8 volumes of CO2. Carbonation will take 10 - 14 days. I personally gave one batch a good 3 weeks of carbonation and conditioning time at 22C and it worked wonders for the beer.
Minimum cold conditioning time recommended by fellow brewers is 2 weeks, though you can open a bottle after 3 days in the fridge making sure all the CO2 had dissolved.
After pouring, small to medium sized bubbles will rise to the surface with good head retention properties. Beer will be clear even without the use of irish moss or similar products. If you desire crystal clear beer, simply leave it in the fridge for a longer period of time.

Flavor Contribution

Here comes my favorite part !!! To be frank, this is a very interesting yeast and it will compel you to experiment more.
As the company reports, this strain produces 'low esters'. But yes, it does give out few esters and do expect a surprise!  I personally had hints of pears and peaches in my beers every time I used it. A fellow brewer used this strain for his American Wheat and noticed mild banana profile. Yet another brewer reported that the hops were accentuated making it a hop forward yeast strain. So basically there is a lot left out for interpretation.

Opinion: Well suited for styles like Kolsch, Altbier and other German ales. Also for Irish Red ales and American wheats. You can experiment with IPAs too. Not suitable for Belgian ales because none of us experienced the subtle spicy character required for Belgian style beers.

So guys, do let me know what you think or if there is any clarification needed. If you notice something else about this yeast do comment in the section below.

Cheers


5 comments:

  1. This comment has been removed by a blog administrator.

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  2. This was a super helpful article. You made a starter with dry yeast? Please explain what you did - I've always been curious about doing just that and never understood why more people don't do it.

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    1. I make starters with dry yeast all the time. It works very well. The only reason people don't do it, is that its a lot of effort and dry yeast is not expensive.

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    2. Thanks for the response and for this article. I've had an interest in using K-97 in a cream ale, but wanted to read more about its practice and performance - this convinced me to give it a shot! If you have a minute, could you please explain your process for a dry-yeast starter? Is it the same as a liquid yeast starter? You've been a great help and I really appreciate it.

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    3. The process for making a dry yeast starter is exactly the same as making a liquid yeast starter.

      I use a calculator like this one -
      https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

      I have a stir plate. So can manage with smaller starter volumes. But you can do it without the stir plate too.

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