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Messages - lupulus

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1
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: December 07, 2016, 02:52:49 PM »

I would love to see the validation tests this company has run.
I am a bit suspicious because many researchers have indicated that measuring DO in the mash is not directly possible, and none of the published data uses a DO meter.

I wouldn't dismiss the utility of the instrument out of hand. While I can concede that it might not be quantitatively accurate at those temps, I expect that it would still be useful and telling in a qualitative or relative way. Trials run with and without DO reduction measures could probably be assessed to some degree.
I agree with you given these caveats  :)
Warm regards

2
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: December 07, 2016, 11:40:26 AM »
I appreciate that Bryan (@Beerery) is trying to simplify the discussion, but in doing so we may be simplifying too much and making too many assumptions.

START OF CHEMISTRY BRIEF
Here some statements that the group should feel free to correct/ improve
- Oxidation-reduction reactions are within the realm of what some have called RedOx chemistry. Here are
some definitions:
* oxidation is loss of e−
* reduction is gain of e−
* oxidizing agent gains e− during reaction and is therefore reduced during reaction
* reducing agent loses e− during reaction and is therefore oxidized during reaction
* oxidized form form of molecule relatively lacking an e−
* reduced form form of the molecule relatively having an additional e−
A molecule with a higher negative redox potential than another molecule will tend to lose electrons (i.e. to be oxidized by reducing another molecule, eg. a free radical) more than a molecule with a lower negative redox potential; and a molecule with a higher positive redox potential will tend to gain electrons (i.e. to be reduced by oxidizing another molecule).
These reactions are of course dependent on the concentration of the reacting molecules, concentration of other molecules that can reduce/oxidize, the pH of the solution, and the temperature of the solution
END OF CHEMISTRY BRIEF

We do not know whether the redox potential of SMB in mash conditions is higher than that of ascorbic acid (it would be my working hypothesis that SMB is a better antioxidant but again, there is no data in our experimental conditions). Remember that SMB will be mostly in the sulfite form under mash conditions, so we cannot use data collected when it was mostly in the sulfite form (at higher pH).
I also agree it is a fair working hypothesis that dehydroascorbic acid (oxidized ascorbic acid) is more prone to regain the lost electron by oxidizing another molecule vs oxidized bisulfite; but again, this is not proven either. It may even be different for L- vs D-ascorbic acid.
If you add gallotanins (Brewtan) to the equation, it will get even more complicated

Bottom line
- it is not proven that mole to mole, SMB is better than ascorbic acid in mash conditions (or Brewtan)
(my working hypothesis is that SMB is better but I do not have any evidence to prove it)
- these are not simple experiments
- if I were to suggest a path, it would be to do rigorous taste tests of the final beer (it is too complicated otherwise)

- the message for homebrewers is to not put all their chips on SMB (yet)

Oh come on, was it my bouncer at the door that was too broad!?!?  ;D ;D

As always thanks for the reply. I should have a permanent preface, that these are my findings.

Thanks Bryan :-)
I think it is important people understand the difference between observations and results from controlled experiments.
There is so much we need to learn.
All the best,

3
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: December 07, 2016, 11:04:46 AM »
I appreciate that Bryan (@Beerery) is trying to simplify the discussion, but in doing so we may be simplifying too much and making too many assumptions.

START OF CHEMISTRY BRIEF
Here some statements that the group should feel free to correct/ improve
- Oxidation-reduction reactions are within the realm of what some have called RedOx chemistry. Here are
some definitions:
* oxidation is loss of e−
* reduction is gain of e−
* oxidizing agent gains e− during reaction and is therefore reduced during reaction
* reducing agent loses e− during reaction and is therefore oxidized during reaction
* oxidized form form of molecule relatively lacking an e−
* reduced form form of the molecule relatively having an additional e−
A molecule with a higher negative redox potential than another molecule will tend to lose electrons (i.e. to be oxidized by reducing another molecule, eg. a free radical) more than a molecule with a lower negative redox potential; and a molecule with a higher positive redox potential will tend to gain electrons (i.e. to be reduced by oxidizing another molecule).
These reactions are of course dependent on the concentration of the reacting molecules, concentration of other molecules that can reduce/oxidize, the pH of the solution, and the temperature of the solution
END OF CHEMISTRY BRIEF

We do not know whether the redox potential of SMB in mash conditions is higher than that of ascorbic acid (it would be my working hypothesis that SMB is a better antioxidant but again, there is no data in our experimental conditions). Remember that SMB will be mostly in the sulfite form under mash conditions, so we cannot use data collected when it was mostly in the sulfite form (at higher pH).
I also agree it is a fair working hypothesis that dehydroascorbic acid (oxidized ascorbic acid) is more prone to regain the lost electron by oxidizing another molecule vs oxidized bisulfite; but again, this is not proven either. It may even be different for L- vs D-ascorbic acid.
If you add gallotanins (Brewtan) to the equation, it will get even more complicated

Bottom line
- it is not proven that mole to mole, SMB is better than ascorbic acid in mash conditions (or Brewtan)
(my working hypothesis is that SMB is better but I do not have any evidence to prove it)
- these are not simple experiments
- if I were to suggest a path, it would be to do rigorous taste tests of the final beer (it is too complicated otherwise)

- the message for homebrewers is to not put all their chips on SMB (yet)




4
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: December 06, 2016, 01:49:51 PM »
The Hamilton VisiTrace DO probes are reported to sense 0 to 2 ppm DO at temps up to 85C. That would suffice for mash use. I was lusting after them at last year's CBC but the $2k price tag was too much for me.

Thanks Martin for taking the time to write.
I would love to see the validation tests this company has run.
I am a bit suspicious because many researchers have indicated that measuring DO in the mash is not directly possible, and none of the published data uses a DO meter.

In the Stability of Beer chapter of the Handbook of Brewing, 2012, August Gresser writes: It is known that oxygen at higher temperatures reacts with polyphenols, anthocyanes and tannoids. Brighter beers that are richer in polyphenols are more sensitive to oxygen in comparison with medium - colored beer and, especially, darker beers. For this reason, the brewer should carefully monitor the presence of oxygen with instruments during wort filtration and also during mashing, wort boiling or in general in the field of higher temperatures. Oxygen cannot be determined during the mashing process – one can take values from empirical procedures...

In Enzymic and Non-Enzymic Oxidation in the Brewhouse,  1999, Bamforth states:
An additional complication concerns the assessment of oxygen consumption at this stage in the process. Direct measurement of oxygen in mash is fraught with difficulty and most people have reverted to redox measurements (using redox probes or colorimetric techniques) to gain an indication of the extent of oxidative damage. The interpretation and relevance of such measurements is by no means straightforward.

5
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: December 06, 2016, 11:56:35 AM »
have there been an large scale, blind tastings, where the participants don't know the variable or what they should be looking for?

So far, I see a lot of people trying out to LODO method, and then saying they taste a difference. The mind is a funny thing when you are actively looking for a result.

Really, just do the mini-mash experiment. It's quite simple to put together and I tested a group of people on it who don't even drink beer. Wort in red cups so they can't see the color difference, allowing them to smell or not smell before tasting, they all could easily pick out the low-O2 sample and all preferred its flavor as a warm sweet beverage.

Still, good data is needed.
- Even detractors of hot side oxidation recognize the effect in color (see O'Rourke)
- To my knowledge, the DO meter is not validated to measure DO under mash conditions
- The see-for-yourself answer is not a valid scientific answer, so until you have the data, you can only say that your observations seem to suggest that but these observations need to be validated by a blinded test
BTW this is coming from someone that has made the same observations in wort...

And in the end, the effect needs to be proven in the final beer, doing many experiments with many yeasts, ensuring that the control beer is well brewed and tastes as planned, doing the well-known triangle test to tease out the odd beer, and if found, check whether the beer is indeed better.


6
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: December 06, 2016, 11:40:48 AM »
I think we all agree we need to stick to the science. We have enough scientific questions as it is.
To summarize my understanding of recent topics and my two cents on them:

- Sulfites do have antioxidant effects in beer. There are published papers on the subject (see Guido 2016 review).
- Sulfites are likely to have an antioxidant effect in wort but there is no published evidence to support this. (And yes, many observations from Brian and other brewers).
- Many authors state that dissolved oxygen cannot be measured in the mash (Bamforth, Gresser) and the published data does not report DO. I have seen tannoids and chemoluminiscence to compare mashes. (So, reference to the DO meter as evidence of the antioxidant effect of oxygen in the mash is questionable; but the chemoluminiscence data is solid).  If anyone has documented validation of DO meters under mash conditions, kindly provide....
- Sulfites may not be the solution for ales. My personal observations are that even at 30ppm SMB in the mash, they can be perceived in the final beer as either sulfite or sulfide flavors. More data is need, but I stopped using them for ales (except for weissbier yeast). I think the effect is yeast dependent and not temperature dependent because I did not notice it either a weissbier or a dampfbier, but again more data is needed.
- Let's not forget that, as an example, there is published data indicating that the preference for a fresh vs a stale lager was 50/50 so low oxygen may not make "better" beer for everyone.

7
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: December 05, 2016, 06:08:24 PM »
SO, what you're telling me is that hundreds of years of research, that all came to the conclusion that meta is not effective as an antioxidant at higher ph's values is incorrect?

@bayareabrewer
I, for one, would like to read all the articles that you mention. I am really interested.
Science is always changing but the state of the art knowledge in the beer world is that if added to beer, sulfites would prevent oxidation, but brewers are so far reluctant to add them to beer so we can only refer to the literature. For example, Bamforth talks about it in the Flavor Stability chapter in Beer, a quality perspective.

https://winemakermag.com/634-solving-the-sulfite-puzzle

http://vinovation.com/ArticleWinepH2.htm

http://www.practicalwinery.com/janfeb09/page4.htm

https://beerbrew.com/words/wp-content/uploads/2014/05/SO2science.pdf

http://morewinemaking.com/public/pdf/so2.pdf

here's a few. This was just from a google search. Give me a little more time and I could find about a billion more. Winemakers know meta like the back of their hands, they've been using it forever. It's common accepted and proven that meta is not an effective antioxidant at higher ph's.

Thanks so much! So, the point these articles make is that according to the SO2 dissociation pK, almost all of the SO2 is present as a bisulfite ion HSO3- at beer pH (4 to 4.5). Given I have not read any wine research at all, I concede that for wine you may need at least some SO2 to be present as sulfur dioxide.
It is a big leap however to state that this concept applies as-is to fermented beer or to beer wort. There are many research papers that directly or indirectly suggest a positive role for sulfites affecting the formation of staling compounds, and no paper I know of that has demonstrated the contrary (ie, sulfites having no effect on beer oxidation).
If you find literature demonstrating that the same effect applies to beer, please let us know.
Cheers :-)


8
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: December 05, 2016, 05:25:50 PM »
SO, what you're telling me is that hundreds of years of research, that all came to the conclusion that meta is not effective as an antioxidant at higher ph's values is incorrect?

@bayareabrewer
I, for one, would like to read all the articles that you mention. I am really interested.
Science is always changing but the state of the art knowledge in the beer world is that if added to beer, sulfites would prevent oxidation, but brewers are so far reluctant to add them to beer so we can only refer to the literature. For example, Bamforth talks about it in the Flavor Stability chapter in Beer, a quality perspective.

9
Ingredients / Re: Brewtan B
« on: November 30, 2016, 09:52:20 AM »
Last Sunday, I brewed a Rochefort 4 with lodo techniques and BTB. I noticed the trub was much more compact than usually, and so more clear wort could be racked off as a nice side effect. Is this lodo, BTB, combination of the two?
Did you combine it with whirlfloc/ Irish moss? What do you mean by usual? Whirlfloc?
Thanks in advance

Sent from my SM-G930T using Tapatalk


10
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: November 22, 2016, 08:21:11 AM »
I thought measuring sulfite level was the intention.

That's what I meant about "missing the forest for the trees". You don't really care about sulfite level. I mean you may if that's what you're after but the point of the sulfite strips is a cheap approximation of your systems DO ingress.

If you know the NaMeta dose you start with and then take even a rudimentary (and approximate) measurement of the residual sulfite level using strips, you get a ballpark figure for how much of your initial dose was consumed scavenging Oxygen.

I agree that if you were after a precise reading of sulfite level that strips aren't the way to go. That's very obvious. What it does do however is give those without DO meters, who want a general idea of how their systems perform in the Low Oxygen process, a chance to approximate in an affordable manner.

There are problems with the validity of DO measurements as well. As an example, in the Handbook of Brewing, August Gresser (Weihenstephan trained brewer) states: "Oxygen cannot be determined during the mashing process – one can take values from empirical procedures."
Do you have any articles in which DO was measured and correlated with other parameters?

11
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: November 21, 2016, 07:25:14 PM »
Is there any validation of the use of sulfite strips in beer?
I understand that reducing substances can artificially lower the reading, and given that LODO main hypothesis is that flavor is enhanced by keeping the malt polyphenols and tannoids in a reduced stated, these can theoretically interfere with the reading, so it seems that there is a need to validate the use of strips in beer by measuring sulfites independently.
Another concern is the interference by sulfides (which are produced by some yeasts in non-negligible amounts). Sulfides can be chelated to nickel and then filtered out but I have not read this being advised in the thread (doing this will certainly add more work to the process).

Sorry, not following?

@Bryan
When one designs a chemical quantitative or semi-quantitative test, one validates the test under a set of experimental conditions and indicates what factors can confound the results of the test. In the case of the sulfite test strips, the instructions specifically warn that using them in a media with reducing agents can confound the results, and separately state that if sulfide can be present, it has to be chelated to nickel and precipitated (as sulfide can affect the reading).
There are other methods to measure sulfite and if a different method (eg, iodometric) gives you a similar result, it would indicate that that one can get accurate sulfite readings in beer or wort or mash with the strips; if not, then one may need to use a third method to reconcile the differences.
Does the question make sense now?

Why go through all that trouble? They are not meant to be that accurate or precise. Sulfite strips are a cheap way to estimate your consumption, not a precise way to determine exact sulfite amounts.

When you draw conclusions and make decisions on how to proceed using data, your data should be accurate.  Lots of people brew excellent beer without using sulfite strips, so I agree that if it is not important to them, they should not use the strips.

12
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: November 21, 2016, 02:36:21 PM »
Is there any validation of the use of sulfite strips in beer?
I understand that reducing substances can artificially lower the reading, and given that LODO main hypothesis is that flavor is enhanced by keeping the malt polyphenols and tannoids in a reduced stated, these can theoretically interfere with the reading, so it seems that there is a need to validate the use of strips in beer by measuring sulfites independently.
Another concern is the interference by sulfides (which are produced by some yeasts in non-negligible amounts). Sulfides can be chelated to nickel and then filtered out but I have not read this being advised in the thread (doing this will certainly add more work to the process).

Sorry, not following?

@Bryan
When one designs a chemical quantitative or semi-quantitative test, one validates the test under a set of experimental conditions and indicates what factors can confound the results of the test. In the case of the sulfite test strips, the instructions specifically warn that using them in a media with reducing agents can confound the results, and separately state that if sulfide can be present, it has to be chelated to nickel and precipitated (as sulfide can affect the reading).
There are other methods to measure sulfite and if a different method (eg, iodometric) gives you a similar result, it would indicate that that one can get accurate sulfite readings in beer or wort or mash with the strips; if not, then one may need to use a third method to reconcile the differences.
Does the question make sense now?

13
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: November 21, 2016, 02:16:17 PM »
Calculations for PMB

INFORMATION NEEDED PMB theoretical conversion to Sulfate      
Potassium metabisulfite molecular mass   222.31   g/mol
Sulfur molecular mass   32.065   g/mol
Potassium metabisulfite chemical formula   K2O5S2   
Sulfate molecular mass   96.060 g/mol
Sulfate chemical formula   SO4   
      
Given the information above      
222.31 g PMB has 2 * 32.065 g of sulfur      
Using the info above 100 g of PMB has   28.847 g of sulfur
Calculation is 100 * 2 * 32.065 / 222.31      
96.06 g sulfate has 32.065 g of sulfur      
28.847 g of sulfur fully converted to sulfate   86.420 g of sulfate
Calculation is 28.85 * 96.06/ 32.065      

14
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: November 21, 2016, 01:57:38 PM »
@ Kit B - you are correct - we are all talking about a maximum theoretical amount given the sulfur coming from SMB, but indeed some sulfur will be dissipated as SO2, some will become hydrogen sulfide, some will remain as sulfite ion and some will oxidize all the way to sulfate ion.

15
All Grain Brewing / Re: Introduction to Low Oxygen Brewing
« on: November 21, 2016, 01:48:58 PM »
INFORMATION NEEDED      
Sodium metabisulfite molecular mass   190.107   g/mol
Sulfur molecular mass    32.065 g/mol
Sodium metabisulfite chemical formula   Na2O5S2   
Sulfate molecular mass 96.060 g/mol
Sulfate chemical formula SO4   
      
Given the information above      
190.107 g SMB has 2 * 32.065 g of sulfur      
Using the info above 100 g of SMB has   33.734 g of sulfur
Calculation is 100 * 2 * 32.065 / 190.107      
96.06 g sulfate has 32.065 g of sulfur      
33.734 g of sulfur fully converted to sulfate gives 101.0588774    g of sulfate
Calculation is 33.734 *96.06/ 32.065      

This calculation assumes that there is sufficient oxygen in the system to allow the oxidation to sulfate to occur

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