Making Candi Syrup in a Slow Cooker

Recently I and some members of my homebrew club brewed 70 gallons of Belgian Dubbel in order to fill a former Merlot barrel. 70 gallons is quite a lot of beer and this brew required a large amount of belgian candi sugar. Seeing as how the stuff costs something like $7/pound at homebrew shops and it is basically just cooked sugar I went in search of how to make this stuff at home.

What I found was that “basically just cooked sugar” isn’t quite accurate. Despite what many online tutorials for making candy sugar tell you, there is a bit more to making candi sugar than cooking sugar syrup until it achieves a desired color. I found the process at the Sui Generis blog. The process is split among two blog posts and you have to do a bit of flipping between the two to determine the recipe which is kind of annoying so I figured I’d outline it here in a more readable way. I’m also making the syrup in a slow cooker which is a different and (I feel) superior method because you don’t have to be constantly monitoring it, stirring super hot boiling sugar, and stressing that it’s getting darker than you wanted. Another note: I’m outlining a 1kg sugar recipe here but accompanying photos are from a 3kg batch so bear that in mind when looking at the photos.

The basic premise behind this method vs just cooking invert syrup until it turns dark is that this method utilizes maillard reactions where the other method is only caramelization. With maillard you can get more complex and desirable flavors like stone fruit, raisin, etc. The main difference between this method and the cooked sugar method is that we’re not using any acid to invert the sugar (acid puts an end to maillard reactions) and are adding a base part way through to really drive the maillard reactions. I’m also making it in a slow cooker over the course of 8-10 hours depending on how dark you want it to get.


  • 1kg table sugar
  • 200ml water
  • 5ml dry malt extract (we need some nitrogen to help drive maillard reactions a tsp is fine)
  • 20ml slaked lime (aka pickling lime aka calcium hydroxide)
  • ~60ml additional water


  • Add your sugar, malt extract and 200ml water to your slow cooker, stir to make sure all of the sugar is wet. Turn the slow cooker on to high setting, put the lid on. If you’re able to weight the lid to help prevent any build up of steam from escaping do so.
  • Combine the slaked lime with the 60ml water in a glass and stir it up and then set it aside to allow it to settle.
  • Go away for an hour or so
  • Return and stir the sugar sludge in the crock pot it probably won’t be fully dissolved quite yet. Put the lid back on and leave for another hour or so.
  • Return to see that the sugar has fully dissolved. At this point our simple heating should have produced some inversion of the table sugar, enough to help with the maillard reactions we’re about to help initiate.
  • Decant the clear liquid that has separated from the lime in the glass, I use a sort of flat ladle spoon to do this. Also be careful as this liquid is incredibly basic and will burn your skin.
  • Add the decanted liquid to your slow cooker to increase the pH
  • Stir your sugar syrup up and replace the lid and weight
  • Go away for a few hours
  • When you come back the room will smell like baking cookies, check on the color, and see where it is at.

When the color/flavor is to your liking turn off the slow cooker and pour the syrup out of the pot and into something else to hold it for storage, mason jars or a disposable foil tray work well. Keep in mind that when this syrup cools it is going to be incredibly viscous and difficult to pour out of containers without warming it up quite a bit. With the slow cooker we aren’t bringing the sugar syrup to crack temp with this method so it will not completely solidify to the point where you can break it into chunks.

This is not all that difficult to do, probably the hardest part is acquiring the pickling lime as it’s no longer recommended for use in pickling. I ordered mine from Amazon.