Gravity info you may or may not know

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histo320

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I've been reading here for the past few days about gravity problems people are having. Mostly not reaching your expected final gravity. After asking the Brewmaster at a local brewery he said the following:

Malted Barley has only 25-30% fermentable sugars. The percentage of sugars in the wort are:
Maltose: 40-45%
Maltotroise: 14-15%
Glucose: 8-10%
Sucrose: 6-8%
Fructrose: 2-5%
Unfermentable Sugars: 25-30%

Typcially, he yeast first eats Sucrose followed by Glucose, Fructrose, Maltrose, and Maltotroise but this can vary depending on the strain of yeast.

Different extracts have different degrees of fermentablility, the darker the extract the less fermenable because of the complex sugars contained in the extract. Dark extract is higher than Amber which is higher than Pale/Light.

For all grain/mashers, you can manupulate the conditions to vary the amount of sugars present in the wort. Basically, you can produce a wort made up of 100% fermentables or non-fermentables.

I knew most of this walking in but it is good to know a bit more of the information. After cross referencing with How to Brew, this is pretty much consistent with the book.

Brew On my friends.
 

Dos_Locos_Brewery

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This sugar profile is plausible, but would be remarkably unfermentable. More typical (from John Palmer's book) would be:

Maltose: 50%
Maltotroise: 18%
Glucose: 10%
Sucrose: 8%
Fructrose: 2%
Unfermentable Sugars: 12%

As you say, grain/mashers have some control over this profile, although from a practical point of view, 0% fermentable and 100% fermentable are not attainable (or desirable). I'd hazard a guess that the range would be more like 60 - 90%. Also it's not right that the sugars are consumed in series - it's a completely parallel process. The yeast will certainly process some faster than others, but I think the order would be more like glucose, (mono-saccharide), maltose (di-saccharide of 2 glucoses), fructose (another mono-saccharide), sucrose (disaccharide of glucose + fructose), maltotriose (tri-saccaride of 3 glucoses), and many others both fermentable and not.

And you're right that there is at least some correlation between wort color and fermentability. Melanoidin formation at various points in the process darkens the malt/wort, and creates unfermentables. But this is no absolute. It is possible to make an extremely fermentable wort, and darken with a very small amount of black patent malt.

Cheers,

Dos Locos
 

SumnerH

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I've been reading here for the past few days about gravity problems people are having. Mostly not reaching your expected final gravity. After asking the Brewmaster at a local brewery he said the following:
...
Different extracts have different degrees of fermentablility, the darker the extract the less fermenable because of the complex sugars contained in the extract. Dark extract is higher than Amber which is higher than Pale/Light.
It varies strongly by brand, too. Laaglander, for instance, is relatively unfermentable compared to something more normal like Briess. Munton's is a bit more fermentable than average.

Because of that, I always stick with the same brand when formulating my recipes (unless using an extract of different fermentability is key to a particular recipe).
 
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histo320

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It varies strongly by brand, too. Laaglander, for instance, is relatively unfermentable compared to something more normal like Briess. Munton's is a bit more fermentable than average.

Because of that, I always stick with the same brand when formulating my recipes (unless using an extract of different fermentability is key to a particular recipe).
+1, I always use Briess/northwestern.
 
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