A reader’s question

Got an email from a reader and would like to address it publicly here. Brandon writes:
“I have read (Greg) Noonan’s book on Scottish ales, but I am not clear on the procedure for caramelizing the wort. I thought you might be able to answer some of my questions.
In the book, he says to lightly caramelize some of the wort. How much wort did he typically use? I have read of homebrewers boiling a gallon of first runnings and reducing it to a quart. Is this too much caramelization or is this similar to what Noonan did?
I have also read that longer boil times do not necessarily increase caramelization but instead increase Maillard reactions, which are two different things. So when making a Scottish ale, am I going for caramelization or Maillard reactions?
Any information you could offer would be greatly appreciated.”

Good question, Brandon – and potentially confusing! As I understand it, Maillard reactions do in fact produce pretty much the same results as caramelization, but due to amino acids rather than actual “burning” of the sugars. Maple syrup, bread crusts, milk caramels, etc. are darkened by Maillard reactions, true sugar caramel and the like are by “pyrolisis”, or burning. In terms of a Scotch Ale, I think we’d be hard pressed to differentiate – true caramelization should be easy to do, although if a Maillard reaction occurred we might not know the difference among all the other complex flavors in the brew…
What I usually do (and I have a recipe, inspired by Greg Noonan’s work, that comes awfully close to a Traquair House clone) is take the first 2 or 3 quarts of runoff (from a 5-gallon all-grain mash with a target OG of around 1080 at least) and boil it in a cast iron pot until it thickens to a syrup-consistency, and almost burns… takes some watching, especially if you are also still monitoring the runoff and sparging the rest of the mash… I will then dilute the caramelized wort with a few cups of ordinary wort and add it into the brew kettle….

I would love to hear from readers with more of a chemistry background, explaining, in layman’s terms, the difference between these two processes, and between their results…