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Author Topic: Experimental Brewing podcast Episode 21  (Read 1731 times)

Offline denny

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Experimental Brewing podcast Episode 21
« on: August 17, 2016, 10:02:33 am »
This episode we talk about two of our favorite online communities and their upcoming distributed competitions. We stop in the pub to do a little talk about mashing obsessions and the law and homebrewing. We head to the library to talk about Scott Janish's article on DMS, causes and cures and his test. Denny and I talk about his favorite homebrew myths before he heads to the land by the waters - Milwaukee - where he talks to Mino Choi, a homebrewer with a culinary obsession and a couple of 50 point entries under his belt. Mino talks his process, his designing and some agressive techniques he uses to drive his fermentations.

We come back to our "Something Other Than Beer" segment with Denny enjoying spending time with Cecilia Chiang, the Chinese cuisine equivalent to Julia Child and we close out with Drew circling back to a lesson from earlier in the show!

https://www.experimentalbrew.com/podcast/episode-21-myth-mino
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Offline homebrewdad7

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Re: Experimental Brewing podcast Episode 21
« Reply #1 on: August 17, 2016, 10:56:37 am »
As the guy behind one of those competitions, it was super cool to get to chat with Denny like this.  Thanks for the love, guys!

Offline denny

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Re: Experimental Brewing podcast Episode 21
« Reply #2 on: August 17, 2016, 11:04:17 am »
As the guy behind one of those competitions, it was super cool to get to chat with Denny like this.  Thanks for the love, guys!

Our pleasure, sir!
Life begins at 60.....1.060, that is!

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The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline narcout

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Re: Experimental Brewing podcast Episode 21
« Reply #3 on: August 22, 2016, 12:33:39 pm »
After listening to the first half of the podcast, I read the DMS article on the Scott Janish site and then the article cited under the Yeast Storage/Health section: Yeast Handling Studies. I. Agitation of Stored Pitching Yeast.

The study involved yeast which was collected from a production fermenter and then stored (for 5 days at 1 degree Celsius) under beer with no agitation, under water with 2 hours of agitation per day, or under water with constant stirring via a Corning magnetic stirrer.  It did not involve making starters.

The yeast stored under water with constant agitation decreased in viability by 25% and in glycogen by 85%.  The yeast stored still under beer or under water with 2 hours of agitation per day decreased in viability by 8% and in glycogen content by 12%.

The authors suggested that the oxygen provided to the yeast by stirring accelerated the metabolic processes of the cells which required expenditure of stored cellular glycogen.  They then noted that had this occurred in wort the glycogen could have been used by the cells to form sterols, possibly in “a concentration sufficient to negate the need for wort oxygenation and to shorten the initial lag phase after pitching” (assuming all the glycogen dissimilated during storage was so used).  However, since the yeast was stored in water under nutrient-deficient conditions, this did not occur.  Once the stored glycogen was depleted, the cells died.

Further, they stated that additional cell losses may have been caused by oxygen toxicity. 

Interestingly, they also estimated that 15% of the of the original cells were lost through mechanical breakage caused by stirring, and this may have resulted in an increase of respiratory deficient mutants (from 1% to 15% of the population) which are believed to be better protected from mechanical breakage due to their smaller size.
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Offline denny

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Re: Experimental Brewing podcast Episode 21
« Reply #4 on: August 22, 2016, 01:08:05 pm »
After listening to the first half of the podcast, I read the DMS article on the Scott Janish site and then the article cited under the Yeast Storage/Health section: Yeast Handling Studies. I. Agitation of Stored Pitching Yeast.

The study involved yeast which was collected from a production fermenter and then stored (for 5 days at 1 degree Celsius) under beer with no agitation, under water with 2 hours of agitation per day, or under water with constant stirring via a Corning magnetic stirrer.  It did not involve making starters.

The yeast stored under water with constant agitation decreased in viability by 25% and in glycogen by 85%.  The yeast stored still under beer or under water with 2 hours of agitation per day decreased in viability by 8% and in glycogen content by 12%.

The authors suggested that the oxygen provided to the yeast by stirring accelerated the metabolic processes of the cells which required expenditure of stored cellular glycogen.  They then noted that had this occurred in wort the glycogen could have been used by the cells to form sterols, possibly in “a concentration sufficient to negate the need for wort oxygenation and to shorten the initial lag phase after pitching” (assuming all the glycogen dissimilated during storage was so used).  However, since the yeast was stored in water under nutrient-deficient conditions, this did not occur.  Once the stored glycogen was depleted, the cells died.

Further, they stated that additional cell losses may have been caused by oxygen toxicity. 

Interestingly, they also estimated that 15% of the of the original cells were lost through mechanical breakage caused by stirring, and this may have resulted in an increase of respiratory deficient mutants (from 1% to 15% of the population) which are believed to be better protected from mechanical breakage due to their smaller size.

Interesting, huh?  Kinda explains why I seem to be getting better performance from a SNS starter than a stirplate starter.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline narcout

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Re: Experimental Brewing podcast Episode 21
« Reply #5 on: August 22, 2016, 01:30:55 pm »
I think it's hard to draw any conclusions from that particular article since it didn't involve making starters, and the yeast being constantly agitated was stored in water not wort.

Assuming any of the same results would be observed in the context of starters, I guess it would be a trade off between mechanical breakage and potentially higher levels of sterols in the viable cells.

Yeah, I did find it interesting though.
Sometimes you just can't get enough - JAMC