Field of Science

Building better ice cream and popcorn - who says physical chemistry is useless?

Physical chemistry, which I teach, has a certain reputation among chemistry majors: as difficult, dull, mathematically intensive, time consuming. There is even a bumper sticker that says "Honk if you passed p-chem!" When you are looking at the Maxwell relations in thermodynamics, it seems hard to imagine that p-chem has any impact on your daily life at all. But in reality, researchers at Purdue University are hot on the trail of better microwave popcorn and using physical chemistry to do it. [See Role of the Pericarp Cellulose Matrix as a Moisture Barrier in Microwaveable Popcorn; Agung S. Tandjung, Srinivas Janaswamy, Rengaswami Chandrasekaran, Adam Aboubacar, and Bruce R. Hamaker; Biomacromolecules].

Unpopped kernels in your popcorn are a pain, particularly when your kids pick them out and leave them in the living room! It turns out that unpopped kernels are even more of a problem in microwaved popcorn (is there any other kind anymore?). The key to getting popcorn to pop is is the structure of the outer hull (the pericarp), which is made of a biological polymer (which is why this was published in the journal Biomacromolecules). Pericarps in which the cellulose polymers exhibit a strongly crystalline structure pop better. The researchers used differential scanning calorimetry and x-ray crystallography to study the pericarp.

Prefer ice cream with your movie? Erich Windhab, at the ETH in Zurich (where Einstein once worked), used physical chemistry and physics to figure out how to make a smoother, richer ice cream - with fewer calories. You can now buy ice cream made with this process (Edy's Grand Light where I live). [See the article by Robert Kunzig in the June 2004 issue of Discover]


  1. Physchem is considered dull? Are majors not required to take analytical chemistry? (Inorg and anal battled it out for dull at my school, anal won time-intensive, though the physchem labs were close; physchem won for difficult and math intensive (see statistical mechanics, generally considered to be the hardest (required) undergrad only course in my entire schoool. Not that I'm, you know, bitter).)

    And I have fallen in love with your blog.

  2. Analytical chemistry is sometimes a course, sometimes distributed through the curriculum, but everywhere there is p-chem!

    Enjoy the blog....

  3. Funny to run across this. I posted on popcorn a few months ago, but for me it's more about physics, or maybe engineering, than chemistry.

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