Yeast differences in sugar utilization

[David219]

I came across this article/study on the Scottlab website and thought it was interesting. The biochemistry of winemaking interests me, but only a fraction of it sinks in!

http://scottlab.com/uploads/documents/The Fermentation of Fructose in Winemaking.pdf

 

[Floandgary]

Quite in-depth but at the same time an easily understood process we all employ. Helps explain the "why" when we do certain things!

 

[heatherd]

I came across this article/study on the Scottlab website and thought it was interesting. The biochemistry of winemaking interests me, but only a fraction of it sinks in!

http://scottlab.com/uploads/documents/The Fermentation of Fructose in Winemaking.pdf

Good info!

Scott Labs' website has so much information, I learned a lot from their section on tannins as well.

 

[Treeman]

A good explanation of why you should use glucose instead of sucrose if you want to step feed your way to a high abv port.

 

[StevenD55]

Thanks for posting that.

 

[sour_grapes]

A good explanation of why you should use glucose instead of sucrose if you want to step feed your way to a high abv port.

Excellent point, Treeman. Now I understand why the WE SI Amarone kit, for example, has you chaptalize with dextrose (i.e., the "normal" form of glucose) late in the fermentation. I seem to recall questions about that on this forum, and I did not know why that procedure was followed at the time. Good stuff.

(As an unimportant side note: Out of curiosity, I tracked down the reference that the Lalvin article cited [Dumont et al., 2009] where the fructophilic index was defined. It turns out that the relevant sentences in the Lalvin article were lifted straight out of Dumont's article, including copying a grammatical mistake!)

 

[JimmyT]

So this is saying that if your step feeding for a high abv you should chaptalize with glucose only? Or should you keep the ratio up? I took it as using glucose only

 

[sour_grapes]

So this is saying that if your step feeding for a high abv you should chaptalize with glucose only? Or should you keep the ratio up? I took it as using glucose only

That is the way I take it! (Glucose only. AKA "dextrose only.")

 

[JimmyT]

I think I read somewhere on here about making a simple syrup breaks sugar down from one form to another and makes it easier for the yeast to eat it. I can't find it anywhere now. Does this sound right or am I thinking of something else?

 

[cmason1957]

I think I read somewhere on here about making a simple syrup breaks sugar down from one form to another and makes it easier for the yeast to eat it. I can't find it anywhere now. Does this sound right or am I thinking of something else?

Inverting sugar breaks the sugar down. Basically, make a simple syrup, but add about a cupful of lemon juice (citric acid) and hold at nearly boiling for about 15-20 minutes.

 

[JimmyT]

Inverting sugar breaks the sugar down. Basically, make a simple syrup, but add about a cupful of lemon juice (citric acid) and hold at nearly boiling for about 15-20 minutes.

I know how to make it, I was talking about the forms that the sugar is in. Like you said it breaks the sugar down, that's what I was talking about. Changes the sugar from what form to another form?

 

[sour_grapes]

It splits the disaccharide sucrose (i.e., table sugar) into two monosaccharides, viz., fructose and glucose.

 

[JimmyT]

That's what I was talking about Paul, thank you. For some reason I was thinking it went from fructose to glucose for some reason. Basically if your chaptalizing to achieve a higher abv then you should use glucose. Glucose=dextrose. Dextrose=priming sugar from the lhbs, correct? If so, can you get dextrose from some local grocery store or is it considered a specialty sugar for home brewing?

 

[Treeman]

As long as you are not chaptalizing above a 12-13% abv wine you should be good with adding sucrose. Pretreating a simple syrup with acid (tartaric) will speed up the hydrolysis of sucrose to fructose and glucose, and you need some acid in your simple syrup addition to keep your TA from dropping.

You can find glucose or fructose at most health food stores. I've use fructose occasionally for back sweetening because it has more sweetness per gram than glucose.

 

[JimmyT]

As long as you are not chaptalizing above a 12-13% abv wine you should be good with adding sucrose. Pretreating a simple syrup with acid (tartaric) will speed up the hydrolysis of sucrose to fructose and glucose, and you need some acid in your simple syrup addition to keep your TA from dropping.

You can find glucose or fructose at most health food stores. I've use fructose occasionally for back sweetening because it has more sweetness per gram than glucose.

How much tartaric acid would you use per cup of sugar?
Is it just the the perception of sweetness or does it actually raise the sg more per gram?
Same sg of both after sweetening, the fructose would taste sweeter?
For fermenting only, has anyone just used all priming sugar (glucose) on a high abv wine to help it not stall? Is there any downside to doing this?

 

[Treeman]

When I make simple syrup, I use 3c water, 4c sucrose, and 1tsp tartaric acid heat to boiling and then simmer for ~30 min. This makes about 1L. I haven't measured the exact number of grams, but it should be close to 5g of tartaric acid in a tsp.


It is only the perception of sweetness that increases more with fructose.

The relative sweetness of fructose is about 2.3 times greater than glucose, and 1.4 times sweeter than hydrolyzed sucrose, so if you use fructose to sweeten a finished wine, you add fewer grams of sweetener.

 

[richmke]

I am chaptalizing an RJS Chocolate Orange port kit, and estimate that it will take 2.5 cups of sugar before the yeast call it a day (already added 1/2 of the f-pack).

At 1.010, I added 1/2 cup of table sugar (cane sugar) on two successive days. It took the table sugar fine.

I am now adding dextros in 1/4 cup increments, and letting it ferment down to 1.002. Seems to take about 1/2 day to do that with a 3 gallon kit.

Interestingly, the dextros is a fine sugar, and it causes a volcano when added to the wine (lots of nucleation points for the CO2 to form). I have more than enough head space in the 5 gallon pail, so I use the fine sugar to degass the wine. Fun to watch.