I'd suggest looking into using Ammonia Carbonate instead of DAP.
In my experiments with trying to make homemade candy syrup, this seemed to produce the best & "cleanest" result. DAP really didn't seem "right". Lye water was better, but the AC seemed best
Having said that, i've been happy with a few of my attempts but none of them really compare to the real thing.
I enjoy the challenge of trying to perfect the process at home, however i'd suspect the professionals utilise an array of specialised equipment like large scale pressure cookers & precise/constant temperature control, possibly also shielding the syrup with CO2 during or after cooking (i suspect oxidation might be an issue with the finer quality of the syrups - note that the manufacturers claim their syrups must be used within a week or 2 or opening the packaging, up to 6 months if kept in freezer, which seems relevant to oxidation, to me).
FWIW, having chased this rabbit hole for a year or 2, and the reading & inter webs research involved, i'd point out (the obvious) that there's a lot of people with lots of different opinions on how to make candy syrup, many of which seem to be at least partially wrong, or optimistic in how close their result is to the real stuff. Candi syrup isn't just carefully burnt sugar. Nor is it as simple as just chucking in a few additives/reagents and applying heat.
I think my last attempts were using Cream of Tartar as the acidifying agent, and Ammonia carbonate as the alkalising agent & nitrogen reagent for the Maillard reactions. I also suspect the Maillard reactions are also quite minimal, so you don't need much.
Good luck!!
EDIT - to answer the question of where to find this, i discovered it's used as a baking agent for certain Greek/mediterranean biscuits/cakes (?) so after much hunting in greek grocery stores, i found a tub of it at the Mediterranean wholesalers in brunswick in melbourne. Maybe there's something like that near you?
