Disaccharides

[wraith]

There is something that has been bugging me for a while, sucrose and maltose are both disaccharides, yet sucrose is considered 'simple' and maltose 'complex' yet they are both disaccharides, why is sucrose more fermentable? Sucrose is Fructose/Glucose and Maltose is Glucose/Glucose, Is it that fructose is more fermentable that makes the combination more fermentable?

Wraith

 

[pokolbinguy]

I could be wrong, but from memory glucose has to broken down to fructose before it can be consumed by the yeast. or something like that.

OR its probably something to do with the difference in bonds between the two molecules, one might be more easily broken via fermentation than the other

Or.....the more simple sugar is more attractive to yeast as they are easier to break down.....damn too many beers and glasses of wine tonight..anyway it has to do with the glycolosis (spelling?) cycle during fermentation

 

[MHB]

When we are talking about beer there are four common simple sugars (Monosaccharides) they are Glucose, Fructose, Galactose and Mannose. Join two of them up i.e. Glucose Galactose to make Lactose, Glucose - Fructose make Sucrose, or Glucose - Glucose and its called Maltose, all are Di-Saccharised.

I dont know who refers to Sucrose as simple sugar and Maltose as complex sugar but they are probably wrong. Both are disaccharides and equally complex.
MHB

 

[gone_fishing_]

When we are talking about beer there are four common simple sugars (Monosaccharides) they are Glucose, Fructose, Galactose and Mannose. Join two of them up i.e. Glucose Galactose to make Lactose, Glucose - Fructose make Sucrose, or Glucose - Glucose and it's called Maltose, all are Di-Saccharised.

I don't know who refers to Sucrose as simple sugar and Maltose as complex sugar but they are probably wrong. Both are disaccharides and equally complex.
MHB

Maltose and sucrose are very similar. Sucrose is further refined.
gf

 

[MHB]

FFS. Did you read what I posted before you quoted it?

It has nothing to do with "Refined" they are made of different monosaccharides. If you don't understand Glucose + Glucose = Maltose, Glucose + Fructose = Sucrose, I can't help you.

Mark

 

[mh971]

Deducing from above

If sucrose has been considered in some thought as being 'less complex' than maltose it would seem plausible that perhaps a glucose-fructose bond is broken down more easily (i.e. with less energy) than a glucose-glucose bond.

If this is so that would explain the myth of one being 'more complex' than the other when in fact they are similarly complex.

This would mean that rather than being simple versus complex or both being equuivalent di-sacharides that one is just more robust than the other.

 

[Thirsty Boy]

The problem here is that confusion is being introduced by the mistaken belief that sucrose is more fermentable than maltose. It isn't, they are both 100% fermentable by yeast.

 

[felten]

It might also be because of the order they're fermented in, its often stated that the yeast will consume the sucrose before the maltose and that while they're doing this they're unable to process the maltose. I was glancing through the yeast book and it says this is the case for glucose, but it doesn't mention it for sucrose.

 

[Nick JD]

We can get hold of 100% sucrose easily, but not 100% maltose and this makes sucrose "more fermentable" than LDME (which contains a lot of longer, less fermentable sugaz too).

 

[Bribie G]

There's a guy on a UK forum (not Jims the other one IIRC) who works in a factory in the UK where they actually produce pure maltose and he takes samples home and uses them in his own brews. He posted on how they do it from wheat starch using a chain of enzymes. I use the tubs of Chinese Maltose and wonder if they are 100% as well.

I also got a bit puzzled by the thing that felten mentioned, with sucrose the literature is always banging on about invertase which the yeast uses to crack the sucrose molecule but what's the enzyme it uses to crack the maltose? Just out of interest.

edit: oops invertase not diastase

 

[Thirsty Boy]

invertase happens outside the cell, and the literature mentions it mostly because there is some thought that in high sucrose fermentations it is produced in excess and that it can result in the "cidery" taste associated with high sugar (ie K&K) brews. So this means that effectively sucrose is treated by the actual cell as though it were glucose - and glucose comes before maltose.

Maltose is transported across the cell wall intact and broken into into glucose by, unsurprisingly, Maltase, or alpha-glucosidase if you like the big words. There is pretty much an enzyme for everything, they are like little chemical fairies swanning about the place and turning not beer into beer... gotta love that.

TB

 

[Feldon]

Not sure if this will help the discussion, but here tis anyway...

 

[wraith]

Thanks for the replies everyone, very interesting to read peoples opinions.

Wraith