The SCIENCE of off-flavors...

SUBJECT: Extract TWANG SCIENCE

MISSION: Provide some science to back up the extract "twang" theories...which typically appear more opinion than fact.


1. Why would old (past it's shelf life) DME/LME lead to the "twang"?

2. What by-product would yeast produce, that could lead to that "twang" flavor? What enviroment would help develop those by products (light, sound, temp, etc.?

3. Why does a full boil have an effect on long term extract beer flavor? How does less boiled H2O=greater chances for "twang"?

4. How does the temperature of the liquid at extract addition time have any effect on overall flavor once fermented?


I hope this helps with the science of extract brewing...something I think is greatly overlooked.


GOAL: Find the #1 Culprit based on real science (that can hopefully be controlled)... chemists, engineers, biologists, and scientific minds please chime in!!!

Thanks again!

J

I don't think you need much science to know the answers to those questions.

1. "Old" anything doesn't taste as good as fresh, that's why even canned goods from the grocery store have "best by" dates on them. Old canned extract darkens and ages, while the bulk LME (which is stored and poured under inert gas) will be exposed to oxygen when it's placed in the container you buy. It's fine when fresh, but with age will oxidize and darken and start to stale. You can taste the difference if you open a can of old extract vs a jug of freshly poured bulk extract.

2. Yeast off-flavors occur just as often in all-grain brewing. That has nothing to do with the extract. Poor technique (underpitching, fermenting at too high of a temperature, etc) related to yeast health cause yeast off-flavors.

3. Less maillard reactions, and less scorching will occur in a bigger boil as there would be less sugar per gallon.

4. It wouldn't. The temperature of the extract when added to wort has nothing to do with the final flavor, unless it was on the flame, sunk to the bottom and burned.

Nothing very "scientific" about any of that, in my opinion.

I appreciate the feedback, but I posted in the brew science forum because I tend to look deeper into concepts.

I guess I didn't make it clear enough...

I am truly interested in understanding the interaction of chemistry, biology, time and other scientific variables that can be manipulated to develop flavors in beer.

I've read a ton on this forum about theorized opinions, based on general knowledge. I'm looking to geek out a bit... and develop a keen association between science and experience...

For the geeks like me out there, I look forward to your perspective...even if this seems elementary to base it off of extract brewing.

Yooper said:

I don't think you need much science to know the answers to those questions.

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Hence brewing dogma persists...

I applaud your efforts year2beer.

This thread is wasting valuable internet space.


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insubordinateK said:

Hence brewing dogma persists...

I applaud your efforts year2beer.

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Well, call it "brewing dogma", but someone assuming that there is "different" science for an extract brew vs an all-grain brew is why I answered the way I did.

There is definitely a whole science to brewing- but not anything that needs to be dedicated to extract. Canned extract darkens and stales, and boiling it in a condensed volume encourages maillard reactions. That's just the way it is.

But aside from using extract to make wort and using grain to make wort in an extract batch, extract and all-grain brewing are the same. Once the wort is made (either through purchasing fresh LME/DME or mashing) there are NO functional differences. That was my point. Or at least, intended to be my point.

wildwest450 said:

This thread is wasting valuable internet space.


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Agreed. But I think Yooper did a pretty good job of answering the questions.

OP, the issue is that you are essentially dealing with the science of food and cooking. In terms of flavor changes, the predominate reactions are oxidizing reactions and browning/Maillard reactions. But these reactions excompass innumerable substrates and resultant innumerable reaction products. It is my understanding that the reactions are largely extremely difficult to predict or at least to separately characterize because of the shear number of different types of reactions.

If you want more on the science of brewing, look in Briggs. Its about the most scientific source you will find about brewing. But based on your reaction to Yooper's post, you may not even be satisfied with that.

ayoungrad said:

In terms of flavor changes, the predominate reactions are oxidizing reactions and browning/Maillard reactions. But these reactions excompass innumerable substrates and resultant innumerable reaction products. It is my understanding that the reactions are largely extremely difficult to predict or at least to separately characterize because of the shear number of different types of reactions.

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From what I gather, I think there is a lot of truth to this. Probably not possible to nail it down to "one culprit". I did dig up a nice review on the role of polyphenols (as antioxidants) in beer flavor stability with plenty of references if you have access to a university library:

http://www.scientificsocieties.org/jib/papers/2010/G-2011-0107-106.pdf

However this is regarding finished beers, but I think it can be applied to stored malts as this is the source of polyphenols (along with hops). Also malt extracts contained extracted compounds that will be more accessible to oxidation reactions which is why, I think, extracts will have a shorter shelf-life than whole grain.

Also the presence of metals will play role in the formation or reactive oxygen species which will definitely affect flavor. Yet polyphenols can bind to transition metals and indirectly act as antioxidants.

From reading through the article, the presence of polyphenols not only protect other compounds from being oxidized, they can add astringency (tannins) to flavor as well as beer haze so it is a catch-22.

We need some food chemists' input.

I read the study, and completely agree with those conclusions. Its actually led me down the road of understanding the molecular structure of extracts vs. Barley.

At this point I believe the off flavor culprit does not sit with the age of the extract, and rather the vehicle it is transported in.

It makes me wonder why extract isn't vacuum sealed in silicone or polymer packages? It would extend shelf life and minimize unsatisfied customers.... which equals repeat customers!

As a business owner, it leaves me slightly flabbergasted... thoughts?

My thought is that if vacuum sealing in polymer package improved shelf life then they would probably do it that way which suggests that your hypothesis is may be wrong i.e. that it is mainly age that is responsible. Staling reactions take place slowly which is why sherry, barleywine etc. improve with age. Beyond that a sealed can (with polymer lining to prevent the previously mentioned metal catalyzed staling reactions) should be as effective at excluding oxygen. The oxygen (or other high ORP substances) in the syrup are doubtless there before it goes into the package. Perhaps chelating transition metals would be an effective means of lengthening shelf life. Storage at cold temperature would probably help too.

ajdelange said:

My thought is that if vacuum sealing in polymer package improved shelf life then they would probably do it that way which suggests that your hypothesis is may be wrong i.e. that it is mainly age that is responsible.

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First off, I have not put forth any hypothesis. Second, I'm not sure I understand your concern? Vacuum sealing with definitely help with shelf life since you are protecting (whatever it is you vacuum seal) from oxygen which is strong oxidizer. Lowering temperature would dramatically slow these reactions over time as would protecting from light.

Age is always responsible for flavor instability but the partners in crime who do all the dirty work are air (oxidizing species present in air), light, and heat.

When I brewed extract back in the 80's, we had a term for that sometimes off flavor. We called it "the metallic". Anyone ever use that descriptor? Maybe the can?

Oh yeah. To quote my mom: "Don't take offense if offense wasn't intended." Great mantra to keep in mind, especially on a forum!

ajdelange said:

My thought is that if vacuum sealing in polymer package improved shelf life then they would probably do it that way which suggests that your hypothesis is may be wrong i.e. that it is mainly age that is responsible. Staling reactions take place slowly which is why sherry, barleywine etc. improve with age. Beyond that a sealed can (with polymer lining to prevent the previously mentioned metal catalyzed staling reactions) should be as effective at excluding oxygen. The oxygen (or other high ORP substances) in the syrup are doubtless there before it goes into the package. Perhaps chelating transition metals would be an effective means of lengthening shelf life. Storage at cold temperature would probably help too.

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I disagree... large companies like muntons wouldn't take the extra step, unless people were able to relate the breakdown of extracts to "off flavors". Currently there seems to be a belief that brewers are to blame... but I disagree with that frame of thought to a point.

Which brings me to a question that is on my mind:

Where did this "blame the brewing technique or Brewer" for bad extract beer start? 99% of AG brewers don't report the same issues... even on their first AG homebrews. It seems a little off to me.

I'd love to hear from a vendor on this one... because I cannot find any research on the extract companies websites....in relation to packaging extracts and oxidation effects over time.

insubordinateK said:

First off, I have not put forth any hypothesis.

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insubordinateK said:

At this point I believe the off flavor culprit does not sit with the age of the extract, and rather the vehicle it is transported in.

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Sure looks like a hypothesis to me.

insubordinateK said:

Second, I'm not sure I understand your concern?

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I'm not concerned - just trying to respond to the request for thoughts.

insubordinateK said:

Vacuum sealing with definitely help with shelf life since you are protecting (whatever it is you vacuum seal) from oxygen which is strong oxidizer.

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As I said, if your hypothesis were correct then it is probable that someone would discovered that the "vehicle" is the problem and changed to another vehicle. The fact that they haven't tends to support the null hypothesis. I also pointed out that extract in a polymer lined can is is protected from the atmosphere. I would wager that considerable care is taken to insure that this is the case.

insubordinateK said:

Age is always responsible for flavor instability but the partners in crime who do all the dirty work are air (oxidizing species present in air), light, and heat.

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As I pointed out it is probably not air that is responsible here but substances which are in an oxidized state in the syrup when it is packaged. (wort is exposed to air during its production despite the best efforts of the brewer). These oxidized substances are aided, according to the paper in doing the "dirty work" by things like the ions of transition metals. In a properly managed brew, reductones are produced as well. In beer, the yeast help the reductones keep the rH low. In packaged syrup the yeast aren't there and staling can take place over time. We don't expect beer to stay fresh for more than a year. Why should we expect that extract would?

year2beer said:

I disagree... large companies like muntons wouldn't take the extra step,

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What extra step? You fill a can to the brim with hot syrup and slap the lid on. It's vacuum sealed. I can't, of course, speak for Muntons or Coopers or anyone else but you'd think someone would have figured it out if there were a better way to package something with a longer shelf life. Good for marketing if nothing else.

year2beer said:

unless people were able to relate the breakdown of extracts to "off flavors".

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They do. Articles, books, postings on the subject abound in which extract brewers are advised to use the freshest extract they can get. Every one knows, including all grain brewers, that very fine beers can be made with extract if it is fresh. One of the local blokes took BOS in a fairly big show with and extract based Weizen and another keeps getting ribbons for his extract based Kölsch.

year2beer said:

Where did this "blame the brewing technique or Brewer" for bad extract beer start? 99% of AG brewers don't report the same issues... even on their first AG homebrews. It seems a little off to me.

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The usual conversation that takes place at the judging table is "Ugh - oxidized. Extract. Must be a newbie". This is often shrugged off as naivete and the score sheets usually contain advice to use fresher extract. He finally brewed that kit that his uncle gave him two Christmases ago - the one that has been sitting in the garage. As I said in a previous post we don't expect beer to stay unoxidized for more than a year. Why do we expect extract to?

ajdelange - what the hell is your problem? You are deliberately misquoting me.

I have put forth no hypothesis about anything but merely provided a study. Then you try to put year2beer's words in my mouth only to go on and refute the words I didn't say. I'm trying to be scientific and impartial and you want to be an instigator.

You are not worth my time.

As an impartial witness, the whole issue started when you replied to ajdelange's post, which was a response to year2beer's post #10, as if he were replying to you.

I could see maybe where he'd get you two confused after that.

So, maybe you ought to cut him some slack. After all, he only did the same thing you did.

insubordinateK said:

You are not worth my time.

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I think if you look around this site (and others), you will see that ajdelange is very well respected. Looks like he did inadvertantly quote the wrong person but mistakes happen. I don't think you should get so upset about it. If I read posts in the Brew Science section, I typically pay more attention to his posts than those of many others.

Also, I understand you are trying to be scientific in your approach but you should also consider that there are many, many science-minded people on this site.

Glad we sorted that out... LOL. Simple mistake... no worries...

Either way, I do want to speak on the last comment made, extract beer makes the best beer (best of show statement) doesn't seem to be the trend. I would think that super fresh barley would provide the freshest Wort... after mash and sparge. Plus you get more efficiency with advanced set ups.

I also want to read these articles that speak about extract shelf life from the manufacturers...

Do you have a link or PDF you could share?

Thanks!

No one said extract makes the best beer. That implies that AG makes inferior beer. The point is that fresh non oxidized extract can make great beer with no off flavors.

seabass07 said:

No one said extract makes the best beer. That implies that AG makes inferior beer. The point is that fresh non oxidized extract can make great beer with no off flavors.

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Right. No one would ever claim that 'extract makes the best beer'. That's simply not true, and no one would say that. What was said was 'fresh extract makes the best beer' but in that case, it was inferred that if you had two extracts side by side, and one was an older extract and one was fresh, that 'fresh extract mades the best (better) beer'.

It's true that fresh extract, along with steeping grains, can make an award winning beer.

Here's what I'm blatantly calling my hypothesis. Since most beginning brewers use extract, their practices are less developed, they have less sophisticated equipment and are more prone to off flavors including twang. Occam's razor points to this as an explanation of the frequently reported extract twang problem. Typically, when they start AG there is a bigger commitment to equipment and more experience with water chemistry and temp control. They might even recognize the twang as one of many more defined off flavors and start calling it by the correct name. I know this is massive generalization and there are plenty of exceptions. Just my opinion, go ahead and tell me I'm wrong.

Wow. Ya got me. I spend endless hours trying to figure out how to misquote people in order to make them, and me, look foolish and to lower the level of discourse in this forum. It's better than Sudoku. Seriously, don't know how it happened. I regret the ruffled feathers. Everyone take a Valium and relax.

Now I only have one question remaining: Who's on first?

So... where do we go from here?

Haha

Firstly, define "Twang" as it relates to beer. I doubt you can solve a problem without having everyone agree what it is up front.

I'd define "twang" as a set of oxidized flavors which lean towards metallic and/or sour. Another (circular) definition would be "off flavor associated with extract beers".

ajdelange said:

I'd define "twang" as a set of oxidized flavors which lean towards metallic and/or sour. Another (circular) definition would be "off flavor associated with extract beers".

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That, but I also feel that extract 'twang' has a certain "extract taste" that isn't present in a well-made beer (extract or AG). Maybe it's excess maillard reactions from a higher SG/lower volume boil, but it's got a really pronounced "extract flavor", almost like eating a spoon of the LME out of the can. Not as sweet of course, but a pronounced extract taste. A better description would be a state, tart, extract-y taste for what I'm trying to get across, I think.

Good Point.

I'll give it a shot, I'm definitely no webster though.

"Twang" flavored beer: A beer that has aged appropriately, gone through all stages of fermentation and bottle conditioning--yet is flat (although carbonated) and filled with an overly sour flavor. The flavor is usually the first and last thing you taste, but can be overwhelmed by hop flavor in an IPA. Typically the beer can be consumed, but the aftertaste left in your mouth sticks around even once you moved on to a different drink.

If we agree there are 3 properties that I think could be elaborated on:

1. Why are twangy beers carbonated but flat (no mouthfeel)? Oxidation is my first thought...
2. Where does the sour flavor originate from? Wort volume or aged extract/grain (we still haven't narrowed it down)?
3. What structure would the beer have that would make it stick to the tongue for so long? This is where my knowledge drops out...any help here would be great.

Back to the science...

My guess is that it is happening during the manufacturing process. There is that hotside aeration thing. Maybe it's real. Maybe they are careless with keeping wort from getting aerated while filling the cans.

I think the point I'm trying to make is that it's impossible to get down to the scientific details when there is not much info on what is actually causing the problem. This thread can do nothing more than speculate the cause of the twang.