Author Topic: Biotransformation  (Read 669 times)

Offline dmtaylor

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Re: Biotransformation
« Reply #15 on: February 05, 2018, 02:22:42 PM »
Another vote that it's baloney.

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It's a statistics thing. If you always say that everything is baloney, then you are right every time you are actually served baloney. Just kidding. You are awesome!
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Offline danpixley

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Re: Biotransformation
« Reply #16 on: February 05, 2018, 11:30:59 PM »
This Palmer interview was one of the best interviews on NEIPA I have heard so far.  I agreed with him on just about everything he said.  Where Palmer went wrong was that he failed to explain that there are different types of "bioconversions".  The word "bioconversion" is a rather generic word for any biochemical transformation that is biologically driven (https://en.wikipedia.org/wiki/Bioconversion).  Fermentation is a form of bioconversion, for example.  The study that Palmer was talking about looked specifically at the enzymatic hydrolysis of glycosides, the Luk Daenen study.  Luk Daenen published a study that found that out of over a hundred strains, there was very weak support for beta-glucosidase in S. cerevisiae, and one strain of Brettanomyces anomalus that had strong activity.  So Palmer is right, there is no evidence for beta-glucosidase activity in ale yeast.

But that isn't the full story.  The 2003 study that was linked showed that there are other bioconversions happening.  They HAVE to be happening because the hops don't contain the compounds that are being found in the finished beer.  There are a lot of different biotransformations of hop compounds during fermentation.  In many cases, they don't know how or why, but there is something going on.  This is a completely separate issue from glycosides though (although in some of these papers, glycosidic reactions have been hypothesized as the cause).

Here are some reviews I've written on the Shellhammer and Daenen studies on these two topics:
http://www.milkthefunk.com/wiki/Glycosides
http://www.milkthefunk.com/wiki/Hops#Hop_Derived_Compounds_In_Beer_and_Biotransformations
« Last Edit: February 06, 2018, 12:40:37 AM by danpixley »
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Offline klickitat jim

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Re: Biotransformation
« Reply #17 on: February 06, 2018, 12:55:51 AM »
Thanks for your thorough input! I'm looking forward to hearing what Denny finds out from the horses mouth. I sense that might pop up in a podcast... no rush.

In the end I just don't want to be running round touting the awesomeness of something that, come to find out, doesn't really exist. Home brewers are phenomenal at that.

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Re: Biotransformation
« Reply #18 on: February 06, 2018, 03:41:52 PM »
Tom is at a conference this week.  Hope to hear from him soon.
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Offline narvin

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Re: Biotransformation
« Reply #19 on: February 06, 2018, 04:56:14 PM »
It's also possible that other factors are having an effect.  I'd expect less oxidation from adding hops during fermentation.  The two aren't mutually exclusive, though. 
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Offline narvin

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Re: Biotransformation
« Reply #20 on: February 06, 2018, 04:56:55 PM »
This Palmer interview was one of the best interviews on NEIPA I have heard so far.  I agreed with him on just about everything he said.  Where Palmer went wrong was that he failed to explain that there are different types of "bioconversions".  The word "bioconversion" is a rather generic word for any biochemical transformation that is biologically driven (https://en.wikipedia.org/wiki/Bioconversion).  Fermentation is a form of bioconversion, for example.  The study that Palmer was talking about looked specifically at the enzymatic hydrolysis of glycosides, the Luk Daenen study.  Luk Daenen published a study that found that out of over a hundred strains, there was very weak support for beta-glucosidase in S. cerevisiae, and one strain of Brettanomyces anomalus that had strong activity.  So Palmer is right, there is no evidence for beta-glucosidase activity in ale yeast.

But that isn't the full story.  The 2003 study that was linked showed that there are other bioconversions happening.  They HAVE to be happening because the hops don't contain the compounds that are being found in the finished beer.  There are a lot of different biotransformations of hop compounds during fermentation.  In many cases, they don't know how or why, but there is something going on.  This is a completely separate issue from glycosides though (although in some of these papers, glycosidic reactions have been hypothesized as the cause).

Here are some reviews I've written on the Shellhammer and Daenen studies on these two topics:
http://www.milkthefunk.com/wiki/Glycosides
http://www.milkthefunk.com/wiki/Hops#Hop_Derived_Compounds_In_Beer_and_Biotransformations

That's cool, thanks for the links.
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Offline erockrph

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Re: Biotransformation
« Reply #21 on: February 07, 2018, 01:19:15 AM »
Wow... the whole biotransformation info has been around for so long that this thread is like flat-earther stuff to me. I don't have all my articles at the ready because I read them years ago, but here's the first hit I get from a 2-second Google search:

https://www.ncbi.nlm.nih.gov/pubmed/10790686

Did anyone read "Hops"? Stan Heironymous went into a fair amount of detail about the whole biotransformation thing, and I had read many of what were his likely primary sources and came to similar conclusions myself. Biotransformation definitely happens with some Saccharomyces strains.

The devil is in the details, however. Biotransformation could mean a lot of things. Which oils get converted by what strains to which byproducts and to what extent? This we don't know.

I don't think I've seen a study that specifically tests one of the common NEIPA strains for specific biotransformation reactions. My gut instinct is telling me that it is contributing to the flavor of these beers to some extent, but there is no way to quantify it at the moment.
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Offline The Beerery

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Re: Biotransformation
« Reply #22 on: February 07, 2018, 01:24:02 AM »
Wow... the whole biotransformation info has been around for so long that this thread is like flat-earther stuff to me.

I get that feeling a lot around here as well.




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Offline 802Chris

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Re: Biotransformation
« Reply #23 on: February 08, 2018, 04:27:36 PM »
Wow... the whole biotransformation info has been around for so long that this thread is like flat-earther stuff to me.

Wait wait wait.... are you telling me you ACTUALLY believe the EARTH is ROUND???? Get a load of this guy  :o