You would expect it to be a problem, but I rarely have any issues with incorporating the THC into hard candy.
I used to use BHO (butane hash oil), but for several years now I only use Distillate. This is any extract (usually Ethanol based extract) that is then distilled the similar to the way liquors are produced from fermented liquids. The THC content runs 80-98% (usually ~85%).
Sometimes I add as much as 1% of the total weight in soy lecithin (liquid), but not always. What I usually do is add the amount of distillate needed to a small beaker, add equal weight of 95% ethanol, put that into a hot water bath (at low simmer, ~175 F) and then add it hot to the cooked sugar mass as soon as target temp. is reached. By the time the THC is added ~1/3 of the alcohol evaporates. It's important that minimal ethanol is added and that it fully evaporates afterwards. If there's residual ethanol in the finished product, it adds to the already present bitterness.
When I add the THC/ethanol, at first I let it sit on the surface for 30-45 seconds- until a decent amt. of ethanol evaporates. Meanwhile I'll be adding the flavoring and coloring to the surface as well. When the mass cools to ~275 F I add the citric acid (it's the monohydrate, so no problem adding it as powder) and then mix it all in thoroughly. The citric acid causes slight foaming, which helps to incorporate everything.
Everything I listed in the paragraph above happens pretty quickly. It's important to have everything ready and practice the process a few times before committing expensive quantities - many times something gets forgotten. If you look at the mass at eye level you can see if there's any separation at the surface - keep mixing 'till it's smooth, homogeneous and slightly dull looking.
Shaping them is a whole separate issue. We're deciding on the equipment for that now. There's no difference for infused candy as for not as far as shaping goes though.
Plain fruit flavored hard candies are some of the strongest tasting edibles - which may be part of the reason they aren't common. There's no fat to hide the distinct tastes that marijuana extracts have (think adding bitter soap to hard candy and trying to hide the taste). And the potency of the extract isn't always the answer either - I've had 97% THC distillate that tasted TERRIBLE , and 75% CO2 extract that was very agreeable. The nature of the impurities is easily as important as the quantity of them. Unfortunately not a lot is available as far as what tastes how. I'm trying to build a body of knowledge on this subject but it's in the early stages. I'd love input if anyone has any.
I know you get better clarity and colors from cooking to 310 F, but I usually go as close to 320 F as possible (without risking browning). That way the surface stays as dry as possible. A glucose syrup with the right carbohydrate profile helps a lot in this respect as well (low dextrose, high maltose, +DE less than 50).
There's tricks that work well - surface coatings of sour sugar (up to 15% citric acid, or equivalent amt's of other ones).
I'd love to hear what worked for anyone else. Really the tastier edibles are those with a decent fat and dairy component - or the best I think is chocolate (which is SO straightforward to make).
