Ok, minor update.
I actually have some Dark Candi Inc syrup now to compare with: Amber & D2.
On tasting there's a few things worth noting.
First up, i'd be pretty certain the D2 uses some sort of alkalising agent &/or amino source - it has a particular flavour in the background that i was getting while using some of the ammonia sources (e.g. Ammonium Bicarb, Lye) to drive melanoidin formation. It's absent in the Amber, so maybe it's either not driven far enough to produce those flavours, or they simply don't bother trying to drive melanoidin formation and just stick to caramelisation reactions.
Secondly, the Amber and D2 are very smooth caramel flavours, whereas mine has more of a sharper toffee element, which i'm assuming is from me pushing the higher temps too much and getting a slight scorching in the sugars.
My last 2 efforts (one with & one without some date syrup) seem to be somewhere between the Amber & D2 - probably more like Amber with a little more oomph, though the sharper "scorch" element might be influencing that assessment somewhat.
Obviously the intention is to eliminate that sharper scorched flavour - it's not unpleasant and might work well in the right beers, but i'm trying to replicate what the Belgians do, and they definitely don't have this element in the Amber & D2.
FWIW, the Date syrup in my last effort seems to round out the fruitier flavour a bit, kinda similar to flavour profile of the D2 (i think). So i'd probably stick with some Date syrup if i was looking to replicate the D2, maybe even increasing the amount to ~30-40%.
@ED, all mine are syrups. It just seemed the easiest way to go.
@Manticle, I'll take a red one, thanks.
:lol: I've got a sneaking suspicion the true process requires high pressure heating, to achieve stable high temps without the issue of gradual boil-off slowly ramping up the temp. I suspect i need to do something like "hold x temp for 1 hr" etc, where x=115°C and so on. 115°C is tricky but doable. It starts getting more hard to hold stable for long periods of time once it goes over 120°C.
(& thanks to Clever Brewing for supplying the Dark Candi syrups - obviously critically important to finally have some real ones to compare against
)