Today’s #AskSisyphus comes from Twitter:
“How DO they get the caramel in the Cadbury Caramilk bar?” (In case the embed doesn’t work)
Now this is kind of right up my alley as an engineer, so hopefully this won’t be too much techno-babble for you. My first design out of college was the hood for a large truck. This hood was to be made out of injection molded plastic and I ended up having to learn all about risers, standoffs and extraction angles (Wikipedia didn’t have an easy picture/page for these two so you’ll have to look them up on your own) among many other things.
This means that when I look at something with a cavity in it I can’t help but see, to some extent, how it might have been made. Look for the seams … or for example, look at Sourdough Rolls and see the sides where they tore off from a string of other rolls. Another great example is if you look at model airplane parts, or other little plastic bits that come attached together.
So let’s take this and think about chocolate and caramel. If I had to do it on my own without knowing anything about their methods I’d start with the knowledge that caramel and chocolate probably have different melting points. Then I’d have some mold with a little plastic peg in the middle that holds a frozen ball of caramel. After that I’d fill the mold with liquid chocolate, cool it down, extract the peg from a hole in the bottom, fill the hole with chocolate then smooth over the bottom so it looks uniform. Done and done. Although, if you want to read why that won’t work, follow the link in the next paragraph and read the naysayer’s comments at the bottom.
This is not how they do it, but they use some of the same ideas and principles. The following website tells it best with pictures and shows the stills for each stage of the process, but I’ve pasted an animated gif of it below. (http://www3.ns.sympatico.ca/mt-edward/cadbury.htm)
And that’s that. Drop liquid chocolate into a cold container, shake it to get rid of any bubbles or voids (open spaces), the edges cool and solidify the chocolate closest to them first, then the mold is turned over and the inner liquid is dumped out leaving just a shell of chocolate. After that a little straight edge comes along and trims the excess or overhanging chocolate (probably reclaimed/gathered below to be reused later thereby minimizing waste). Caramel is poured into the open shell, shaken/vibrated for the same reasons as above, and cooled so it’s got its own hard exterior. More chocolate is poured on top to create the bottom of the piece, it’s shaken, cooled, and trimmed and you’re off to the races.
That there is how you can make anything like this. Take advantage of different heat capacities and melting points, work your molds and your process accordingly, and you’re good to go.
For fun you might want to go watch one of the commercials that won Cadbury a Clio award in the 1970′s:
Thank you CapnJunkie for the submission and support. If anyone else has anything they’d like to know, let me know, so we can both know.