Kettle caramelization (maillard reaction) and fermentability

Does kettle caramelization (maillard reaction) render some sugar unfermentable like when kilning the carapils (which is only about 5% fermentable)?

Would a long boil (say 90 to 150 minutes) raise the FG to a noticeable difference compare to a more usual boil length (60 minutes)?

Caramelization and Miallard reactions are completely different things.

Caramelization is the browning and flavor compound creation between two sugars. It typically occurs in high heat, low moisture situations. Caramelization adds toffee like and yes caramel flavors.

Miallard reactions (there are a lot) are enzymatic browning reactions between an amino acid and sugar. Since Miallard reactions cover a vast array of browning reactions, its hard to nail down temperatures. They typically occur in a normal wort boil. They are also what cause toast and seared meat to taste great. Miallard reactions are typically considered to add toasty, bready and some slight "caramel" like flavors.


Are you talking about purposely caramelizing wort in the kettle, like you would for a Scottish Ale? Or are you talking about the slight caramelization that occurs in a concentrated wort boil?

Either way, it isn't the best way to control unfermentables.

Does long boil necessarily mean higher final gravity?

If I were to boil the same wort an hour compare to two hour would the final gravity be the same?... same yeast and same conditions.

Paco said:

Does long boil necessarily mean higher final gravity?

If I were to boil the same wort an hour compare to two hour would the final gravity be the same?... same yeast and same conditions.

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Neither the starting gravity nor the final gravity would be the same because you'd have less wort left after the 2 hour boil; this would make both the SG & FG higher. You'd also end up with less beer.

If you boil longer, the bigger factor is boil off, like mkling said. Boiling for 2hrs will boil off more water, making a more concentrated wort (higher OG). You will have also produced more melanoidins through Miallard Reactions. That will not significantly impact specific gravity though.

Guys,

I don't think Paco is asking about whether boiling longer raises the OG through evaporation. Paco, I think what you're asking is whether kettle caramelization renders some sugars unfermentable, lowering the fermentable/unfermentable ratio, and, if you were to add water to the boil in order to maintain a constant OG, raising the FG.

Let's try to figure this out: Even in a highly-attenuated beer, you can still taste the presence of crystal malt. So, my guess is that yeast cannot metabolize all the products of caramelization.

Palmer notes that "In general, the darker the extract, the more complex sugars it will contain and the less fermentable it will be."

And a thread on Northern Brewer notes that in one person's system, each lb of C 40 raised FG about 3 points.

So, even though the fermentability of a malt depends on mash temperature, pH, and water/grain ratio, it looks like caramelized malts are in general less fermentable than the same uncaramelized malts.

Kettle caramelization is the same class of reaction that occurs in making crystal malt. In both cases, malt sugars react with one another at a high concentration in the presence of water. I think it's safe to conclude that kettle caramelization has the potential to render some sugars unfermentable, and, all things being equal, raise FG.

But the bottom line is that the fermentability of a wort is not easy to predict. Malt companies do not publish any standard measure of fermentability, and even though we know that higher mash T results in less fermentable wort, I haven't seen anything quantifying the effect. Sounds like a job for science.

drummstikk said:

Guys,

I don't think Paco is asking about whether boiling longer raises the OG through evaporation. Paco, I think what you're asking is whether kettle caramelization renders some sugars unfermentable, lowering the fermentable/unfermentable ratio, and, if you were to add water to the boil in order to maintain a constant OG, raising the FG.

Click to expand...

Exactly what I was refering to. I since learned from pro brewers and books that boiling longer doesn't affect FG by much... but it does a little (less than 1.005 I was told on a average).

Ah, 5 points could be pretty significant, 10% of a 1.050 beer! Cool. I am glad to know it.

Up to 5 points... at the very "worst" (3 hours or more of boiling).