Thursday, December 17, 2009

Food Science Friday: Pop Rocks!

Our food scientist friend, Aaron, recently gave us a Sizzling Bacon Bar, a milk chocolate bar embedded with both bacon and "popping candy", known non-generically as Pop Rocks. Overall, the popping that came with eating the chocolate was fun, but the chunks of bacon that got caught in my molars was not as appealing.

You may wonder what is the science behind the magic of Pop Rocks? Students of the confectionery sciences should go directly to the source and review US Patent 4,289,794. In that work (1981) food scientists at General Foods described an improved the process that built on the prior art in order to maximize the popping sensation in the candy.

The basic process is fairly straightforward: a sugar blend is heated to a molten condition, quickly mixed with gas under pressure, and then cooled and solidified under pressure. You can imagine the resultant product as a hard sugar glass (like brittle) that is broken into tiny pieces, but with each shard containing many tiny pressurized gas bubbles (usually carbon dioxide). When the sugar starts to dissolve in your mouth the walls surrounding the bubbles break down and the pressure releases yielding the characteristic 'pop'.

The scientists at General Foods perfected this process by establishing heating and mixing conditions (near 280F) that created fairly large gas bubbles (most between 300-350 microns in diameter). A sensory panel helped establish the optimum conditions for creating bubbles that would maximize this popping sensation.

I wonder if the original scientists envisioned their invention being practiced once day as an inclusion in a chocolate bar also containing bacon?


salsita said...

This entry begs the question, "If you eat pop rocks and drink soda, what will happen?" You know the whole stomach explosion urban legends that have been flying around ;)

Justin said...
This comment has been removed by the author.
Justin said...

Interesting question . . . I think I'd test it in a bowl first, but it's interesting to think about.

In the case of Mentos and Diet Cola eruptions that have been documented, the thought is that the Mentos (mint apparently works best as it has a matte surface) have a surface that provides many nucleation sites for bubbles to form as the CO2 rapidly comes out of solution. The gelatin and gums in the Mentos may help reduce the surface tension allowing the bubbles to grow and probably also helps stabilize a temporary foam.

Pop Rocks would provide a little of their own CO2 to the above equation, but unsure about the rest . . .