After the above mentioned boil-over, i had lost 50-100ml.
So i added ~1/6 tsp DAP, then tested the pH and discovered the syrup was ~pH5.5.
Added increments of Lye water to hit pH9+, totalling another ~2 tsp of Lye. This all meant i'd added several times the previously indicated amount of alkalising agent (NB: this could be as my Lye is more dilute than i expected).
Just thought it might be worth mentioning, to indicate that perhaps the pH of the syrup needs to be tested prior to heating for the caramelisation step to ensure we get the Maillard reactions, and not carbonisation, occurring.
Anyway, i continued through the process to hit ~135°C. Let the temp drop a bit, mixed in another 1/4 cup of water, then reheated to 135°C again. Currently letting it cool down.
Unfortunately, it seems to have a slightly DAP/ammonia smell and taste to it. Not sure if this is right, or if it indicates i added too much DAP or Lye. I might try another batch soon, using less DAP and using however much Lye is required to hit pH9, then making sure no over-boils occur. FWIW, it seemed like as it boiled, it was gradually boiling off the ammonia (& DAP); or rather, it was gradually converting to whatever in the syrup. The amount of DAP i added should be more to suit the "Dark Amber" version of Candi syrup, which is achieved at ~143°C, so i may've simply fallen short of this and really just needed to hit a higher temp to "consume" the DAP/ammonia.
FWIW, the recipe used today was:
250g White sugar
250g Dark sugar
1 cup water
1/2 tsp citric acid
Heated to boil for 30mins, then allowed to cool (had to go to dinner)
1 tsp DAP
1/2 cup water
1 3/4 tsp Lye Water
(boil over)
2 tsp Lye water
1/6 tsp DAP
Heated to 135°C, then taken off heat
Slowly added 1/4 cup water
Heated back to 135°C, then allowed to cool
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So next time, i'll go 3/4 tsp DAP & try to be more precise with the Lye addition to hit ~pH9. See if that alters the smell/taste i'm detecting.
FWIW, this version in which i ensured the syrup was alkaline during the caramelising step didn't seem to have the burnt tones of the previous batch.
Also, fwiw, after everything was completed i dissolved a little syrup into water to test the pH, and it came up as roughly pH5.5. So no worry with alkalising any wort/beer it's added to !
It does make me wonder though how long it stays alkaline after i've added all this lye. In which case, am i wasting my time with trying to hit pH9 or do i need to add incremental amounts of lye, etc??
While we're speculating: I'm also not sure about using Dark sugar. I'm sure it's great for certain results, but i'm not sure if i'm a fan of the molassesy flavours it brings. I'm after caramel and fruity plum flavours. I'm not sure Dark sugar or molasses starting flavours will get me this in a beer. TBH, given i've not fermented any of this yet, i'm just trying to guess really! I think the Dark sugar would be great in a Dark Strong to get the rummy flavours, but maybe not what i'm aiming for.