Hydrolysis of Sucrose

[Brockness Monster]

I am creating this thread so that we can discuss the hydrolysis of sucrose without crowding out other threads. Please give me time to look up some peer reviewed articles.

 

[VikeMan]

Thanks. I look forward to seeing those papers.

For reference (for others), this is a continuation of a tangent from another thread, beginning more or less with this post and my reply to it: https://www.homebrewtalk.com/threads/alternative-to-d-45-candi.737825/#post-10499088 I would summarize the tangent as a discussion of "How much sucrose in wort is inverted through hydrolysis during the wort boil, and how do we know?"

 

[mac_1103]

Not to start a tangent on a thread was created to end a tangent on a different thread, but why does it matter? There's this enzyme called invertase that yeast express constitutively. Yeast are also at least as adept at transporting sucrose as they are at transporting glucose and fructose. So from a fermentation standpoint, I can't see that it makes much difference how much sucrose is inverted during the mash and/or boil. I thought the reason for using invert sugars in brewing was their flavor contributions, which depends more on caramelizing than hydrolizing.

 

[VikeMan]

Not to start a tangent on a thread was created to end a tangent on a different thread, but why does it matter?

Because science, of course. But from a practical standpoint, let's say you're brewing a beer (or maybe a seltzer) with a lot of sugar. If the yeast have to invert the sucrose by themselves, there's a metabolic cost to that. It might (or might not) just explain why people claim different results (flavor-wise) between using sucrose and corn sugar, for example.

Yeast are also at least as adept at transporting sucrose as they are at transporting glucose and fructose.

Do (beer) yeast transport sucrose? I have been under the impression they don't... that they secrete the enzyme for the split to happen outside the cell, and that the resulting glucose and fructose are transported into the cell. (More science of questionable importance perhaps.)

 

[Brockness Monster]

Having to relearn a lot of these symbols, calculations and jargon from organic chem and food chem 11 years ago.

To start I will just post the basic chemistry equation of the Hydrolysis of Sucrose

C12H22O11 + H2O = C6H12O6 + C6H12O6
or
Sucrose + Water = Glucose + Fructose

So already we can see that hydrolysis happens in plain water. How much is the question.

 

[Brockness Monster]

Not to start a tangent on a thread was created to end a tangent on a different thread, but why does it matter? There's this enzyme called invertase that yeast express constitutively. Yeast are also at least as adept at transporting sucrose as they are at transporting glucose and fructose. So from a fermentation standpoint, I can't see that it makes much difference how much sucrose is inverted during the mash and/or boil. I thought the reason for using invert sugars in brewing was their flavor contributions, which depends more on caramelizing than hydrolizing.

While invert sugars can contribute flavor, Caramelized sugars and Maillard sugar solutions (D45, D90 etc. are maillard sugars) will contribute quite a bit more. Also Inverted sugars are really easy to burn and create harsh acrid flavors.

 

[mac_1103]

Do (beer) yeast transport sucrose? I have been under the impression they don't... that they secrete the enzyme for the split to happen outside the cell, and that the resulting glucose and fructose are transported into the cell. (More science of questionable importance perhaps.)

It's actually kind of in between I guess. Sucrose gets cleaved in the periplasmic space - inside the cell wall but outside the cell membrane.

 

[mac_1103]

So already we can see that hydrolysis happens in plain water. How much is the question.

Well of course, since hydrolysis literally means that the linkage is broken by the addition of water. But in the absence of some kind of catalyst? In a simple syrup that hasn't been heated I think the answer is little or none.

 

[Brockness Monster]

https://pmc.ncbi.nlm.nih.gov/articles/PMC2664835/

In this article the abstract states that it would take 440 years for 50% of Sucrose to hydrolyze into Glucose and Fructose at 25C. There is a table in the article that shows hydrolysis rates at different temperatures. The very right-hand side of that chart is very close to 100C. Not knowing the math well enough I took to google and found some very smart people talking about this very graph.

https://chemistry.stackexchange.com...ucrose-to-undergo-hydrolysis-in-boiling-water

If their math is correct, it would take about 11.5 days to convert 63% of the sucrose. Well outside of the time period I was thinking of when I stated "boiling in a water solution takes care of most of it".

The thing I find very interesting is how much faster Glucose and Fructose degrade than Sucrose, and does that correlate in an acidic solution? The world may never know (tootsie pop anyone)

Ok, so I guess we move on to acidic solutions and see if I can find some info on hydrolysis in the pH range of 5.0 - 5.5

 

[mac_1103]

If their math is correct, it would take about 11.5 days to convert 63% of the sucrose.

But it would probably take less than 11.5 hours to convert 100% of it to a burnt crisp on the bottom of a ruined pot.