Do Refined Sugars Cause Fusel Alcohols?

[Bernie]

Fusel alcohols are not formed from sugars - at all. The are formed from amino acid metabolism from proteins (The Ehrlich pathway). Since temperature will influence fusel alcohol production, it may be that previous experience of using refined sugar in wort was to increase temperature due to increased yeast metabolism when the sugar was added.

Anna

Most brewers here apply this, subconsciously. We ferment at lower temperatures than airing cupboard temps. people used decades ago. Wine producers who use large vats also pass the wine through a cooler during fermentation to prevent the build up of heat.
Generally, we aereate the wort, in one way or another, at the start of fermentation.
I also have a hypothesis about dried malt extract boils before fermentation, which I find accelerates the fermentation rate. When a solid dissolves it may appear to have formed a solvated solution but much of the solid could still be in the form of small aggregates that don't scatter light ie the liquid seems clear. It's only after longer boiling times that the extract is fully dissolved and quickly digested by the yeast. In some discussions in this forum people have mentioned how boiling extract reduces "home brew twang". Could it be that the reason is that the yeast is less stressed when the dried extract is easier to digest? Let's not forget that the yeast is only producing alcohol because it finds itself in unfavourable, anaerobic conditions.

 

[Bernie]

Personally I always use invert sugar and I seem to remember a few years back reading yeast prefer cane sugar to beet sugar.

Invert sugar is sucrose that's been hydrolysed into glucose and fructose (golden syrup and honey) by invertase or a weak acid such as lemon juice.

 

[Hop_it]

Most brewers here apply this, subconsciously. We ferment at lower temperatures than airing cupboard temps. people used decades ago. Wine produces who use large vats also pass the wine through a cooler during fermentation to prevent the build up of heat.
Generally, we aereate the wort, in one way or another, at the start of fermentation.
I also have a hypothesis about dried malt extract boils before fermentation, which I find accelerates the fermentation rate. When a solid dissolves it may appear to have formed a solvated solution but much of the solid could still be in the form of small aggregates that don't scatter light ie the liquid seems clear. It's only after longer boiling times that the extract is fully dissolved and quickly digested by the yeast. In some discussions in this forum people have mentioned how boiling extract reduces "home brew twang". Could it be that the reason is that the yeast is less stressed when the dried extract is easier to digest? Let's not forget that the yeast is only producing alcohol because it finds itself in unfavourable, anaerobic conditions.

I'm really enjoying this exchange of information/views. Some of the chemistry is beyond me, but I've been brewing long enough to understand the principles. What is becoming clear to me is that there is no direct cause and effect relationship between the creation of (excessive levels of) fusel alcohols and the use of refined sugars, but in some circumstances there is a potential knock-on effect because of what else might be happening to the yeast in that environment - some of which we can influence and some not.
There are so many variables, and it is such a complex biochemical system, that we as home brewers have little hope of measuring and controlling it with any accuracy. A professional brewer making the same core beers again and again has the possibility/necessity to refine his/her process parameters to achieve long term quality and consistency. As home brewers most of us probably do not make the same beer many times over, and if a brew doesn't turn out quite to our liking, or has an obvious fault, we do something different next time. We have to rely on own experience, accumulated knowledge, and perhaps a few "rules of thumb" because we don't have the benefit of being able to run controlled experiments many times to prove the theory. In the majority of cases the best we can do is develop a hypothesis (as you suggested above), and use that as a guide to future practice.
I think that authors, such as Palmer, do their best to offer easy to follow guidance on how to avoid or correct common problems. It is almost inevitable that they will oversimplify the science because they are not writing textbooks. However, that said, it is this kind of shared knowledge, and a few "rules of thumb" that help us to be better brewers, and helps to develop the craft of homebrewing to such a high standard compared with 40+ years ago when I started

 

[PhilBrew]

They can also be induced by wide variation in pH, depriving yeast of nutrients or by fermenting only in fructose which is one of the sugars in sucrose.

... and precisely what nutrients do refined sugars provide (other than carbohydrates, of course)? Have you deliberately chosen to overlook the fact that adding refined sugars places an increased "workload" on the yeast, which will mean they'll require extra nutrients to take on that "task", which may lead to them being deprived of nutrients, or is that just carelessness? Add to that the information I posted in my first post in this thread, above, which explains the "double-whammy" of refined sugars; that by suppressing (some of) the yeast's "appetite" for maltose, use of refined sugars will place extra burden on the yeast (the other yeast in the colony, those that haven't had their ability to utilize maltose suppressed), thereby further increasing their requirements for nutrients, for them to "finish the job"; and by adding refined sugars (gravity without nutrients) you are considerably increasing the chances of nutrient deprivation.

Your conclusion that "adding refined sugar to beer wort isn't going to increase fusel alcohols" simply isn't supported by the scientific evidence, that you dug out and cited ... you appear to be sticking to your original conclusion and trying to bend the evidence to fit. It won't work!

Cheers, PhilB

 

[Alan_Reginato]

That's a little more complicated.
Esters and fusel alcohol are synthesized when there's alcohol fermentation process in the presence of amino acids or FAN.
Yeast consume FAN and oxygen to growth.
Maltose and maltotriose are slowly metabolized than sucrose, frutose and glucose.
So... the sooner the yeast start to produce alcohol, without consume most part of the FAN, more esters and fusel alcohol it will produce.
Also, temperature plays a important role in the fermentation process, because it increases the assimilation speed of the sugar by the yeast.
But don't worry too much about this, because not even the scientists know the exactly way that it works. There are some interesting papers in internet. Error - Cookies Turned Off

 

[DocAnna]

@PhilBrew My apologies that this appears to have been taken personally. I try to live the NHS values that I work in my day to day role and this means I try to work collaboratively, with respect and dignity, and a commitment to quality. I also have an academic background so am aware of the pitfalls of selective quoting of articles. I will say that while I quoted some articles I did read around the subject to a greater extent than quoted on the forum here, and have tried to present a fair summary of the understanding gained. I would rather those on the forum read up on the articles referenced and formed their own views, your views are respectfully yours and I wholly respect that, I was presenting an evidential base and conclusions from my reading. Academic discourse and disagreement has a long and veritable history so thank you for your perspectives and I think it's well worth having such counter views for those reading to form their own views.

Anna

 

[Buffers brewery]

... and precisely what nutrients do refined sugars provide (other than carbohydrates, of course)? Have you deliberately chosen to overlook the fact that adding refined sugars places an increased "workload" on the yeast, which will mean they'll require extra nutrients to take on that "task", which may lead to them being deprived of nutrients, or is that just carelessness? Add to that the information I posted in my first post in this thread, above, which explains the "double-whammy" of refined sugars; that by suppressing (some of) the yeast's "appetite" for maltose, use of refined sugars will place extra burden on the yeast (the other yeast in the colony, those that haven't had their ability to utilize maltose suppressed), thereby further increasing their requirements for nutrients, for them to "finish the job"; and by adding refined sugars (gravity without nutrients) you are considerably increasing the chances of nutrient deprivation.

Your conclusion that "adding refined sugar to beer wort isn't going to increase fusel alcohols" simply isn't supported by the scientific evidence, that you dug out and cited ... you appear to be sticking to your original conclusion and trying to bend the evidence to fit. It won't work!

Cheers, PhilB

I think that’s what @PhilBrew intended to write @DocAnna so no apology needed.......at least not from you.

 

[micklupulo]

I am new to this thread and having little or no chemical knowledge am nevertheless intrigued. My professional work used to involve reducing complicated contrary arguments to brief summaries as a starting point to elaborated later as necessary. May I suggest/ request that the opposing views be so reduced so that we can all get back to "enjoying this exchange of information/views" as so nicely put by Hop_it?

 

[Brudru]

First of all I just want to say thanks for everyone's input! As a new homebrewer this is why I post on these forums - it's great to see such a free flow of information and views and it definately has given me a lot to digest and think about which I appreciate on my new quest for homebrewing knowledge!

Brief summaries are also appreciated (if not for myself but anyone else who happens upon this thread/question) as I too possess little chemical knowledge but I think I get the gist of most of what was said!

And to inject some levity and possibly a little irony to the topic - I just poured a whole bag of table sugar into a kit'n'kilo beer kit lol

 

[dad_of_jon]

First of all I just want to say thanks for everyone's input! As a new homebrewer this is why I post on these forums - it's great to see such a free flow of information and views and it definately has given me a lot to digest and think about which I appreciate on my new quest for homebrewing knowledge!

Brief summaries are also appreciated (if not for myself but anyone else who happens upon this thread/question) as I too possess little chemical knowledge but I think I get the gist of most of what was said!

And to inject some levity and possibly a little irony to the topic - I just poured a whole bag of table sugar into a kit'n'kilo beer kit lol

I suspect if you like the end result you'll do it again. If not you wont

I've found MJ's triple can be a bit fusel-ly Despite keeping to its temp range. It needs 6 months conditioning to suit me. Lovely drop when aged.

 

[Brudru]

I suspect if you like the end result you'll do it again. If not you wont

I've found MJ's triple can be a bit fusel-ly Despite keeping to its temp range. It needs 6 months conditioning to suit me. Lovely drop when aged.

I suspect not, but I feel like I've been spoiled by coming into homebrewing so late - I want a taste of the not so good ol days as a reference point!

Who knows though, self experimentation and experience can yield some surprising results!

 

[Hop_it]

I suspect not, but I feel like I've been spoiled by coming into homebrewing so late - I want a taste of the not so good ol days as a reference point!

Who knows though, self experimentation and experience can yield some surprising results!

If you really want to know what homebrew tasted like back in the old days you can try brewing with a can of EDME liquid malt extract, some stale English hops, and yeast from the bottom of a Worthington White Shield bottle, or failing that some baking yeast. . . . . . It was usually drinkable - but only just
PS - Oh, I nearly forgot . . . . . You will also need to serve it from a poorly carbonated plastic pressure barrel at room temperature.

 

[DocAnna]

If you really want to know what homebrew tasted like back in the old days you can try brewing with a can of EDME liquid malt extract, some stale English hops, and yeast from the bottom of a Worthington White Shield bottle, or failing that some baking yeast. . . . . . It was usually drinkable - but only just
PS - Oh, I nearly forgot . . . . . You will also need to serve it from a poorly carbonated plastic pressure barrel at room temperature.

This is one of the reasons it took about 20 years for me to come back to homebrewing after our household's earlier trials, and it's really difficult to shake off that reputation for warm, bland brown liquid that was thought of as beer or wine pretty much only because of the label.

Anna

 

[Hop_it]

This is one of the reasons it took about 20 years for me to come back to homebrewing after our household's earlier trials, and it's really difficult to shake off that reputation for warm, bland brown liquid that was thought of as beer or wine pretty much only because of the label.

Anna

Yes, the craft of homebrewing has come a long way in recent years . . . . . . and that's even allowing for the inevitable failures and/or cock-ups that blight us all from time to time. I started both home brewing and county wine making in ~1975, and I still have a copy of my first homebrew book. The quality of information is dreadful compared with what anyone can access today. I just thumbed through it, and it made me smile

 

[micklupulo]

Yes kits in the 70s and 80s produced bland stuff with only a passing resemblance to beer though in the early 80s Boots introduced a more expensive range with liquid yeast including a "London Bitter" and a Stout which I recall were a great improvement. Also at that time I did a dry kit which was pretty good and did not have the typical twang though would have been even better if I had then had the knowledge and willpower to leave it for a month after bottling!

 

[Hop_it]

Yes kits in the 70s and 80s produced bland stuff with only a passing resemblance to beer though in the early 80s Boots introduced a more expensive range with liquid yeast including a "London Bitter" and a Stout which I recall were a great improvement. Also at that time I did a dry kit which was pretty good and did not have the typical twang though would have been even better if I had then had the knowledge and willpower to leave it for a month after bottling!

I'm sure that most kits of that era were just as bad as the limited range of raw materials that were available. I have only ever made one kit during the whole of my brewing life. It was in the early 1980s. and was (according to the proprietor of the local brew shop) a dead ringer for Boddingtons Bitter, which was at that time a favourite of mine. Needless to say it wasn't anything like it, so I carried on doing things my way, i.e. all grain, but with very crude (mostly homemade) equipment. . . . . . But it was fun