Yeast Biotransformation – Got any good research / reads?

Discussion in 'Homebrewing' started by InVinoVeritas, May 12, 2016.

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  1. InVinoVeritas

    InVinoVeritas Initiate (0) Apr 16, 2012 Wisconsin

    I was reading the following article from Craft & Brewing:
    https://beerandbrewing.com/VxailioAAHvvsLAv/article/yeast-a-force-behind-ipa-2.0

    I'll also be reading the hot link within the article:
    https://beerandbrewing.com/VL2BdCYA...r-no-moss--inside-the-alchemists-heady-topper

    Interest quote:
    “A beer that hits 50 IBUs with a California-ale strain might only come up as 35 IBUs when fermented using a British-ale strain, even though the original wort is the same,” says [Erik] Jensen [Green Flash].

    I’ve loosely come across the term yeast biotransformation doing what more than just making ethanol. Does anyone more research on the techno geek side? Let me open the question a little more . . . I'll take any thing more technical reads regarding brewing.
     
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  2. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,181) Dec 15, 2005 Pennsylvania
    Pooh-Bah Society

  3. jbakajust1

    jbakajust1 Pooh-Bah (2,528) Aug 25, 2009 Oregon
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    Thanks for the reads gents! Really enjoyed all 3.
     
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  4. wspscott

    wspscott Pooh-Bah (1,934) May 25, 2006 Kentucky
    Pooh-Bah Society

    thanks for the links.

    another interesting quote

    Those same researchers later experimented with blending different varieties of geraniol-laden hops, trying to see whether they could replicate the citranellol qualities found in hops such as Citra. They found that blending hops high in geraniol increased the amount of geraniol and citronellol in finished beer, enhancing the citrus character. For example, a tasting panel perceived a beer made with Apollo and Bravo (high in geraniol) hops as more flowery and citrusy than one brewed with Apollo alone. The same was true of a beer that included a combination of Simcoe and Bravo compared to Simcoe alone.
     
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  5. hopfenunmaltz

    hopfenunmaltz Pooh-Bah (2,611) Jun 8, 2005 Michigan
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    Stan said to try that combo a while ago, Nugger and Cascade is another he says to try.
     
  6. psnydez86

    psnydez86 Initiate (0) Jan 4, 2012 Pennsylvania

    Now I know where my Apollo and Amarillo pellets are going....


    Thanks guys.
     
  7. FOBjared

    FOBjared Initiate (0) Apr 1, 2016 Washington

    Said where??
     
  8. hopfenunmaltz

    hopfenunmaltz Pooh-Bah (2,611) Jun 8, 2005 Michigan
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  9. FOBjared

    FOBjared Initiate (0) Apr 1, 2016 Washington

  10. bulletrain76

    bulletrain76 Maven (1,287) Nov 6, 2007 California

    As far as the IBU difference goes, I think that is due to the cell wall properties of different yeast strains and how much iso-alpha acid they absorb during fermentation, which is not biotransformation, which typically refers to changes in aromatic chemicals caused by yeast.
     
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  11. SFACRKnight

    SFACRKnight Grand Pooh-Bah (3,274) Jan 20, 2012 Colorado
    Pooh-Bah Society Trader

    I also believe that the yeast in suspension cover the flavor of the hops and take the edge off the bitterness.
     
  12. nickfl

    nickfl Initiate (0) Mar 7, 2006 Florida

    There was a presentation a couple of weeks ago at this years CBC about new research into various theories mentioned in some of the above links. I can't find a link to the actual presentation or the papers behind it, but this is the seminar in question: http://schedule.craftbrewersconference.com/activ-portal/show-planner/detail/session/23/

    The main takeaway was that their research is still generating more questions than answers, but I also got one practical point and two myth busted bits of information out of it.

    1. They found that whirlpool hop additions had the largest effect on overall hop aroma in finished beer, surprisingly even more than dry hop additions.

    2. Total oil content in hops does NOT correlate with hop aroma in finished beer. This goes back to the hop quality being more important than quantity issue that is mentioned in one of the links above. They still haven't found a way to quantify "hop quality", but oil content isn't it.

    3. Biotransformations of geraniol do occur but unless you add pure geraniol and enzymes they apparently don't occur in quantities significant enough to impact aroma in beer. There is some contribution that yeast makes to hop aroma, but its not as simple as turning geraniol and linalool into citranellol, its some more subtle synergistic effect. They also found that lager yeast has this effect, but much less strongly than neutral ale yeast and that phenolic off flavor positive yeast actively dulls hop character. They didn't have any data pertaining to the estery non POF yeast that people are using for "New England" IPAs, but that would have been very interesting and hopefully they will explore that in the future.

    I am a little sketchy on that last point as the chemistry is way over my head, but it did confirm something that I had learned from experience without quite realizing it: if you are going to make a Belgian IPA or hoppy wheat, estery notes match hop character and phenolic ones don't and you have to choose yeast strain and fermentation temperature with this in mind.
     
    #12 nickfl, May 17, 2016
    Last edited: May 17, 2016
  13. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,181) Dec 15, 2005 Pennsylvania
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    How was this determined? Was it via a sensory panel?

    Cheers!
     
  14. nickfl

    nickfl Initiate (0) Mar 7, 2006 Florida

    Yes, it was definitely a sensory panel. If I recall correctly, they were all using a sensory panel at some point since they were concerned with what correlates with the perception of hoppiness rather than just measuring specific hop compounds
     
  15. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,181) Dec 15, 2005 Pennsylvania
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    Was there any discussion from a comparison perspective to the experiment conducted by Rock Bottom in 2010 (see link below)?

    In the Rock Bottom experiment which involved 35 breweries the findings of that sensory panel was: “A combination of late hoping and dry hopping (procedure 3) resulted in greater hop aroma than longer late hopping.”

    The above quote is from the Stan Hieronymus Hops book (page 202).

    Cheers!

    http://www.mbaa.com/publications/tq/tqPastIssues/2010/Abstracts/TQ-47-2-0623-01.htm

    @telejunkie
     
  16. nickfl

    nickfl Initiate (0) Mar 7, 2006 Florida

    No, there was no reference to that study, though I remember seeing a presentation on it a few years ago. I believe that in this study, they were doing separate groups of samples that had hop additions either in the boil, whirlpool, or dry and none that used more than one of those. I don't think the presenter was trying to say that whirlpool without any dry hopping should be used in a real world environment, just that whirlpool additions were surprisingly aroma efficient.

    If you are interested I can send you a link to the presentation or a PDF if that doesn't work.
     
  17. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,181) Dec 15, 2005 Pennsylvania
    Pooh-Bah Society

    Yes, please. I would like to read more about this recent CBC presentation.


    As a ‘reminder’ the Rock Bottom experiment considered four cases:

    There was a Ray Daniels presentation at NHC 2009 discussing the Rock Bottom experiment:

    Rock Bottom conducted a late hopping experiment (in 2008 or 2009?) solely using Amarillo hops:

    Four approaches to finishing hops

    – 1 lb/bbl total per trial

    • Short – 50 mins stand in hot wort

    • Long – 80 mins stand in hot wort

    • Dry – all dry hopped

    • Half – half dry, half long stand”

    Cheers!

    Jack
     
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