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HOMEBREW Digest #4629
HOMEBREW Digest #4629 Fri 15 October 2004
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
FOY 2004 -Response- stress vs biomass yield-Fredrik ("Rob Moline")
Re: Stainless Steel Pump Fittings ("Rob Dewhirst")
Subject: Re: Electric Brewery ("Jodie Davis")
pH adjustments ("3rbecks")
Fortnight Of Yeast, 2004 - yeast washing. Acid wash versus Chlorine Dioxide ("Thomas, Chris")
Up and down versus longways ("Jay Spies")
Pump orientation (Kent Fletcher)
serial vs parallel ("Dave Burley")
Split Rock 2004 HB Competition ("David Houseman")
Coffee Roasters Digest ("Pat Babcock")
Orientation of March pumps ("Mike Sharp")
FOY, 2004- Response - Repitching Yeast- Steve Smith ("Rob Moline")
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* Questions submission: 10/11 - 10/22/2004 *
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Date: Thu, 14 Oct 2004 21:41:18 -0500
From: "Rob Moline" <jethrogump at mchsi.com>
Subject: FOY 2004 -Response- stress vs biomass yield-Fredrik
Dr. Fischborn and Dr.Waldrop, thank you very much for
hosting another fortnight of yeast! This is like Xmas for us.
First I'm sorry to post so "long" and not very distinct questions
but if I just made it short there may be misunderstandings, so I
try to explain some of the motives and elaborate the questions.
Your and everyone else's comments on these issues are much
wanted!!
I have some questions regarding yeast that just to set them in
proper context are related to my attempt to understand yeast
and make a computer simulation of a beer fermentation. I am
currently modeling the states, active dormant and dead. And
the transitions are considered by transition probabilities
(statistically that is), and the transition functions are supposed to
be state functions of yeast, wort and fermentor variables. The
below question all relate to stress and biomass yield and to an
extent the transition probabilities between states. I hope
to decompose the stress into some principal stresses, and find
how the depress the biomass yield (but also how they cause
damage and death, which is another side of it)
Q1 --------------------------------------------------------------
Tracing back to Balling, many formulas in brewing, including
alcohol/FG/OG formulas tend to assume a fixed biomass yield of
some 5%. As I understand this is an empirically determined value,
that I assume is an effective average under "typical conditions".
But as far as I understand the biomass should be a dynamic
and in an extended dynamic treatment I doesn't seem valid to
treat the biomass yield as a constant? Stirplates in starters
are but one example.
Note: I am aware that respiration levels does increase the
biomass yield too, but that is not what I am after here. I am
trying to understand stress depression of the yield.
Considering the biomass yield vs. time, during a batch fermentation.
Since stresses build up, and especially external sugars drop in the
very end I am assuming that the biomass yield must drop during
fermentation. For example, as the sugar concentration is low the
rate of energy production drops.
Actual Q1)
How low is the cellwise biomass yield at EOF, just before the
cells start to tend to go dormant? What do you think about the
idea that the biomass yield drops to close to zero? What about
correlating the transition from active to dormant with the biomass
yield drop?
The idea I have is that the biomass yield in turn would depend on
the free energy balance. Incomes - expenses. Expenses also
including possible stress factors, transport costs etc.
If you feel this still is a dim question perhaps you can elaborate
about the topics of dynamic biomass yield and biomass - stress
correlation?
Q2---------------------------------------------------------------
Actual Q2)
In a normal batch fermentation, how would you rate these
different factors that depress the biomass yield?
: CO2, alcohol, concentration gradients on culture,
UFA/sterol drop
When using a stirplate but *not* aerate, what factor is most
important being responsible for the increased biomass yield?
i.e. I want to if possible put numbers on how much the CO2
supersaturation depresses the biomasyield. etc.
Have these things been quantified, and isolated from other stress
factors? What if you stir in an pressure gas chamber of high
CO2 pressure, would the benefit from removal of gradient be
significant still? Or is it some mechanical excitation of the cells?
Q3 ------------------------------------------------------------
As alcohol tolerance are supposed to relate to pitching rates,
sterol levels and also other add-on stress factors, I wonder what
the conditions are for the alcohol tolerance numbers that you
sometimes find for strain descriptions? It seems clear that there
has to be a limit, but it also seems that the limit can be stretched?
(i.e. it's not fixed) so the question is thus
Actual Q3)
How does yeast companies typically *define* the alcohol
tolerance limit? i.e.. what is the exact experimental setup/conditions
and numerical procedure used to arrive at the alcohol tolerance numbers?
- -----------------------------------------------------------------
/Fredrik
Fredrik,
Thank you for your very interesting questions.
First of all we have to admit that we are not qualified to advise you
with specifics on the modeling aspect.
You are absolutely right that stresses are going to affect negatively
biomass and ethanol production. At the end of fermentation the general
yield is very low. But you have never a homogenous cell culture meaning
you will find a wide range of yeast generations. Most of the cells at
the end of fermentation are still quite healthy but because of the
conditions they are in they are are not reproducing quickly.
With respect to stress factors it is almost impossible to give specific
values. If you just look for one stress under defined conditions (like
ethanol concentration) you will get a number. As soon as you add another
factor to the ethanol stress like temperature your number will change.
This is unlikely to be a consistent and easy to understand relationship.
...we are not trying to put you off your project but you can imagine how
difficult your task is with all the relevant parameters taken into
account.
There was a poster presented at the World Brewing Convention in San
Diego this year in which the presenter demonstrated a model for beer
fermentation and propagation. But he was focusing on a few key
parameters and achieved relatively good correlation with practical
fermentation results. We will get some more information together and ask
Rob to pass it on to you.
Question 2
It is difficult to rate the different factors because as the
environment
changes their impact will change. Concentration gradient will probably
be most important towards the end of fermentation because the lack of
ATP production will make it difficult to transport anything against the
concentration gradient. CO2 and alcohol accumulate together but it is
easier to remove the CO2 effect than ethanol so therefore ethanol is
probably more important. CO2 concentration is depending on the
hydrostatic pressure in the fermenter. The taller the fermenter the more
important the CO2 levels become. As for the UFA/Sterol drop, it will
happen and the amount of UFA/Sterols at the beginning coupled with the
addition of Oxygen at the beginning will determine the impact of the
drop.
On a stir plate the removal of CO2 is probably the main improvement to
a
static fermentation. But improved distribution of the yeast in relation
to nutrients and ethanol should be considered as well.
As for CO2 supersaturation you could determine the impact on biomass on
its own but then again these numbers are probably not relevant under
normal brewing conditions.
Question 3
Mainly from experience. We encourage our customers to give us feed back
on their experience with our products. For some strains we will do our
internal testing under our standard conditions to determine alcohol
tolerance. But this is a subjective test. Other producers will have
their own tests.
Finally on the growing subject of sugar consumption; Kurt Thorn and
Alan
Meeker are absolutely correct. To complicate things further the delay in
maltose and maltotriose consumption is also, in part, due to induction
of genes by maltose and maltotriose presence. Sugars like glucose
fructose and sucrose do not require their presence to have their
transporters in the membrane, maltose and maltotriose do.
Keep up with your good work
Forbes & Tobias
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------------------------------
Date: Thu, 14 Oct 2004 21:49:13 -0500
From: "Rob Dewhirst" <rob at hairydogbrewery.com>
Subject: Re: Stainless Steel Pump Fittings
> Has anyone found stainless steel fittings to attach to the
> input/output threads of a March pump? I have been using brass
> fittings from the hardware store, but would like to upgrade to
> stainless steel. All web searches have yielded nothing.
>
> Thanks very much for a great forum!
www.mcmaster.com will have everything you need. Search for "stainless steel
pipe fittings".
------------------------------
Date: Fri, 15 Oct 2004 07:32:40 -0400
From: "Jodie Davis" <JodieDavis at adelphia.net>
Subject: Subject: Re: Electric Brewery
Reading about your Heat Sticks Pete, reminded my of the stick heaters we
used up north to heat the horse's water buckets in the winter. So, I
searched a few online tack shops and found this one:
http://www.doversaddlery.com/product.asp?pn=X1%2D4758
They've improved since I was a kid!
The description says this one can bring a bucket of water to a boil. For
a challenged tinkerer (my mediums are fabric and clay and soil, not
electronics--no wonder I only made it through one year of engineering
school!) is there an easy way to make/buy some kind of controller for
it?
How's this for a turn of events: My husband would like to get my brewing
off the $1200 glass cook top and out of the kitchen.
Jodie Davis
www.rubberduckie.net
www.jodieandcompany.com
www.friendsinthebee.com
------------------------------
Date: Fri, 15 Oct 2004 07:32:34 -0500
From: "3rbecks" <3rbecks at sbcglobal.net>
Subject: pH adjustments
John
The main reason to adjust the pH of your brewing water is to get the pH of
the mash itself into the correct range. (5.2-5.4) You need to use pH papers
or a meter to measure the pH of the mash. Adjusting the water without
checking the mash pH is shooting in the dark.
If your efficiency and the flavor of your finished beer are acceptable, I
would probably leave well enough alone.
Phosphoric acid (food grade) might be a better choice for acidifying your
water, as it does not tend to flavor the water like lactic acid does.
Another option would be diluting your tap water with RO filtered water to
reduce the pH, but that method also reduces the mineral content of the water
as well, so salts may have to be added back after dilution.
If your mash pH is in the proper range, I wouldn't even mess around with
water adjustments. If it ain't broke, don't fix it.
Rob
Kansas City
------------------------------
Date: Fri, 15 Oct 2004 10:10:26 -0400
From: "Thomas, Chris" <CThomas at wilmorite.com>
Subject: Fortnight Of Yeast, 2004 - yeast washing. Acid wash versus Chlorine Dioxide
I was wondering if you might comment on your opinion of acid washing
versus using a chlorine dioxide (CLO2) wash. It seems that the use of
CLO2 might be a bit easier and quicker than an acid wash based on [very
limited] reading related to this subject.
-Is this something that might be relevant to a homebrewer?
-If you think this is a viable option, do you have any practical hints
and/or suggestions on this method of washing yeast.
FWIW, below are some links to relevant articles.
http://www.birkocorp.com/brewing/yeast.asp
http://www.brewingscience.com/yeast_care.htm
Regards, Chris.
------------------------------
Date: Fri, 15 Oct 2004 10:45:14 -0400
From: "Jay Spies" <jayspies at citywidehomeloans.com>
Subject: Up and down versus longways
All -
Dave Burley quoteth thusly:
>>>Jay Spies says:
- -----------
"Yikes! I know that many people here on the HBD, as well as B3 (sponsor of
the HBD) use these pumps vertically mounted."
- -----------
I suspect there may be some confusion about what is a horizontal and what is
a
vertical mounting.<<<
Well, not really. Seeing as how the mounting plate is on the same plane as
the shaft, it's not too hard to figure out what orientation is vertical and
what orientation is horizontal, as it relates to /mounting/. I think many
people have gotten my comments skewed, here. My whole reason for bringing
B3's vertical mounting option into the thread here is that they sell a "pump
mounting bracket" which is basically a slotted metal piece with 2 screw
holes for attaching to a brew stand. See part #H357. This can be used to
mount the pump /vertically/. That's what I was referring to. I didn't mean
the flow axis, as the orientation of the pump head is moveable to change the
direction of flow, which would allow for horizontal mounting with varying
flow directions.
Technically speaking, then, vertical = up and down, while horizontal =
longways.
;)
Jay Spies
Head Mashtun Scraper
Asinine Aleworks
Baltimore, MD
------------------------------
Date: Fri, 15 Oct 2004 08:34:36 -0700 (PDT)
From: Kent Fletcher <fletcherhomebrew at yahoo.com>
Subject: Pump orientation
Jay Spies said:
"Yikes! I know that many people here on the HBD, as
well as B3 (sponsor of the HBD) use these pumps
vertically mounted."
Jay, I can't remember ever seeing a picture of a brew
rig with the pump mounted vertically. The orientation
the manufacturere is speaking of refers to the rotor
and motor shaft. The motor shaft should be level
(parallel to the ground). They are not talking about
the orientation of the suction and discharge
connections.
BTW, the vast majority of pumps require horizontal
positioning, this is not something peculiar to mag
drive units.
Kent Fletcher
Brewing in So Cal
------------------------------
Date: Fri, 15 Oct 2004 15:09:00 -0400
From: "Dave Burley" <Dave_Burley at charter.net>
Subject: serial vs parallel
Brewsters:
Alan Meeker says he spent a lot of time with me offline discussing serial vs
parallel processing of carbohydrates .
That may be, as I dumped my old files so can't look it up, but my point is
that any model ( which was the subject of my comments to /Fredrik) should not
be serial but take into account all possible reactions. Some will be slowed
down by the presence of other sugars and such, which I commented on, but need
to be included in a comprehensive kinetic model.
Many texts in biochemistry make the assumption about this to simplify the real
world complexity of multiple reactions for the reader. Check in the literature
for kinetic data and you will see what I am talking about.
Keep on Brewin'
Dave Burley
------------------------------
Date: Fri, 15 Oct 2004 18:18:22 -0400
From: "David Houseman" <david.houseman at verizon.net>
Subject: Split Rock 2004 HB Competition
This is the second notice of the homebrew competition on November 20th, at
the Split Rock Resort in the Pocono's of Pennsylvania in conjunction with
their annual Micro Brew Festival. Contrary to any other information,
judging will only be on Saturday. Entry fees, $5, will go to the American
Diabetes Association. This is a sanctioned competition judging all beer,
mead and cider styles. Entries should be shipped to The Resort at Split
Rock, One Lake Drive, Lake Harmony, PA 18624, Attention: Shelly Kalins Lutz,
for receipt from November 6 to November 17. Two (2) brown or green bottles
with no markings are required. Any standard entry forms identifying the
brewer and the appropriate entry category/subcategory are acceptable. Any
standard homebrew competition entry and bottle identification forms are
acceptable. Take special note that we will use the former, 1999 BJCP style
guidelines; not the new 2004 guidelines. Get this from the BJCP web site at
www.bjcp.org.
Judges and Stewards will be needed and they should contact Shelly Kalins
Lutz [srinfo at splitrockresort.com] or me to secure a position. Judges and
Stewards can hand carry their entries if they pre-register with payment.
All judges and stewards are required to be present by 8:30 so we can get
started promptly at 9am. Checks should be made out to The Resort At Split
Rock. Judges will receive an entry to the beer festival or entry to the
beer dinner for their efforts and need to indicate which they wish when they
commit to participate. The BOS winner will receive a complementary weekend
for two at next year's Split Rock Beer Fest as well. But just entering
makes you a winner for helping a good cause. More information will be
available at the Split Rock web site:
http://www.splitrockresort.com/beerfest/. Or contact them at:
spevents at splitrockresort.com.
David Houseman
Competition Organizer
david.houseman at verizon.net
------------------------------
Date: Fri, 15 Oct 2004 20:24:50 -0400
From: "Pat Babcock" <pbabcock at hbd.org>
Subject: Coffee Roasters Digest
At the request of friend Arnold Neitzke, I have added the Coffee Roasters'
Digest to the portfolio of hobby lists on the HBD. S-ubscribe via
coffee-request at hbd.org, post via coffee@hbd.org. Arnold is serving as list
moderator.
Enjoy!
- --
See ya!
Pat Babcock in SE MI
pbabcock at hbd.org
------------------------------
Date: Fri, 15 Oct 2004 17:42:16 -0700
From: "Mike Sharp" <rdcpro at hotmail.com>
Subject: Orientation of March pumps
Some are asking: when we discuss vertical vs. horizontal, do we mean the
body of the pump or the flow (perpendicular to the body)?
Pumps are rated with respect to the axis of rotation of the pump and motor.
Flow has nothing to do with it--some pump housings can be rotated to give
you different discharge directions.
It will usually say on the motor or pump label. Larger pumps may have
motors that can be mounted in any direction, but then you must check the
pump. It depends how it's coupled to the motor. If the impeller is mounted
on the motor shaft, use the motor rating. If there's a flexible coupling
between them, check both ratings.
Regards,
Mike Sharp
------------------------------
Date: Fri, 15 Oct 2004 21:01:43 -0500
From: "Rob Moline" <jethrogump at mchsi.com>
Subject: FOY, 2004- Response - Repitching Yeast- Steve Smith
FOY, 2004- Response - Repitching Yeast- Steve Smith
First, my apologies for such a basic question, but in my research I have
noticed that some people suggest reusing yeast by pitching wort over the
existing trub/yeast in a primary fermenter immediately after racking the
beer that had been on it into a secondary fermenter, or by harvesting some
of that yeast to use with the new batch of wort. Other people, including
Wyeast and/or White Labs and John Palmer provide information for washing
yeast when taken from the primary fermenter before repitching it. Or, if
timing is right, it is preferable to harvest yeast from the bottom of the
secondary fermenter at bottling time, or by top harvesting ale yeast as it
is found in the foam during primary fermentation. I recently reused yeast
for the first time. I opted to harvest a pint of yeast/trub (placed in a
sanitized jar) from the bottom of the primary after racking off the
all-grain beer, and repitched about half of the yeast/trub a couple days
later in a different style beer that called for that same variety of yeast.
The wort fermented practically over night (when I checked the gravity it had
dropped to the desired level). Did I follow an acceptable practice, or am I
likely to end up with off flavors in my second batch of beer off of the same
yeast (consider that I used good sanitation)? I realize that autolysis
could contribute to off flavors in the second batch if the yeast/trub was
exposed to wort for too long a period.. I had fermented on the trub for
eight days with the first batch, and plan on racking off the trub after five
days in the second batch.
Steve Smith
Steve,
Yes, you did follow acceptable practice. Usually the shorter the time until
you repitch the yeast the better. If your fermentation finished after one
day that might indicate that you have over pitched a bit. 5-6 g of crop
yeast slurry per liter of wort is a good pitching rate. Or since during
fermentation yeast multiplies up to four, five times of the original amount
you could use roughly a quarter of your crop yeast.
Acid washing the crop yeast makes sense if it is done properly; it will
lower the risk of bacteria contamination. But you have to be careful with
the temperature. Temperatures around 4 C guarantee higher viability than
warmer temperatures above 10 C.
You can harvest the yeast when your main fermentation is finished and the
yeast is settled. If your second fermentation is already finished after one
day you can probably rack the beer off the yeast after 3 days. You are right
that you can get off-flavors from autolysis if you leave the beer too long
on yeast after the fermentation is finished.
Regards
Forbes & Tobias
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End of HOMEBREW Digest #4629, 10/15/04
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