Don’t let the name freak you out – Molecular Gastronomy is just the scientific exploration of food preparation. It isn’t just about cooking, but using science to create some fairly unique culinary curiosities. One of them, the one highlighted in our video, uses the same scientific principles used at the Rice University Center for Biological and Environmental Nanotechnology (CBEN) to create nanocapsules. We like doing this one at the Children’s Museum of Houston whenever we do homemade ice cream. But, before we get into the dessert toppings, let’s have a quick appetizer on nano!

To understand the basics of nano (shorthand nanotechnology, nanoengineering, nanoscience, etc.), we need to think small – really, really, really small. To get an idea, an average 4 year old is about a meter tall; nano is a billionth of that. Find the millimeter (mm) scale on a ruler and imagine a million lines between each of those. That is a nanometer (nm). Comparing a nanometer on a meters stick is like comparing the entire Earth to a marble. A virus is about 70nm long, a cell membrane is 9nm thick, DNA is about 2.5nm wide, and fingernails grow about 1nm every second. It is SMALL.

The “nanoscale” often referred to in discussions about nano ranges from 1nm-100nm. The interesting thing about materials when they get that small is that they start to demonstrate unusual properties – faster chemical reactions, remarkable lower resistance to electricity, etc. Nanotechnology involves the manipulation of materials at the nanoscale to take advantage of these unusual properties. When these properties are harnessed in large scale, they can have a huge impact. To learn about what’s so big about the super small, check out the website www.whatisnano.org.

Now, let’s get back to dessert!

What You Need

  • Blender
  • Measuring cups and spoons
  • Droppers or syringes
  • 3 Bowls
  • Sieve or slotted spoon
  • Water
  • Dessert Topping (we used chocolate, but most kinds will work)
  • Food grade sodium alginate (available at several websites like this one)
  • Food grade calcium chloride (available at several websites like this one)

NOTE: You can actually purchase molecular gastronomy kids from several websites like this one.

What to Do

  1. Blend ½ tsp. food grade sodium alginate with 1 cup of water until powder is dissolved
  2. Add 4 tbs. of flavoring (in this case chocolate syrup) and blend again.
  3. Pour into bowl and set aside. Let it sit for 20-30 minutes until the bubbles have subsided.
  4. Pour 2¼ cups of warm water into a second bowl.
  5. Add ¾ tsp. of food grade calcium chloride to warm water. Stir until dissolved.
  6. Fill a third bowl with clean water.
  7. Place a sieve into the calcium chloride solution
  8. Use a syringe or dropper to drip the chocolate solution into the calcium chloride solution, letting the sieve catch the capsules. If you don’t have a sieve, you can use a slotted spoon to retrieve them, but it is harder.
  9. Lift the sieve from the calcium chloride solution and put into the plain water for a rinse.
  10. Drop onto your ice cream! (or dessert of choice)

UPDATE (1/7/11) – get a full lesson plan of this activity here.

What’s Happening?
The little capsules that are forming are being created by self-assembly. Self-assembly is just what it sounds like – when structures form automatically when provided the correct conditions. Snowflakes self-assemble as do other crystals and, in fact, all living things, too! The key is provide the right conditions. In this case, the sodium alginate reacts with the calcium chloride, causing the alginate to self-assemble a gel-like shell around the flavoring, creating a flavor-filled casing!

So what does self-assembly have to do with nano? Well, working directly with objects at the nanoscale is very, very difficult and very, very time consuming. Plus, it take a WHOLE LOT of production at that scale to create anything at our scale. But, using self-assembly, we could create large amounts of nanoscale objects relatively quickly. The key is to determine the right conditions for the assembly to occur! How sweet is that?!?