Week 2: Energy, Temperature, Heat - Harvard Style

Harvard Online Food Science

We all know that heat is a form of energy, and energy causes change. Whether you make a creme brulee, filet mignon or sourdough loaf, how much change depends on things you can quantify.

So right off, we learn the Equation of the Week: Q = mcp delta t

That's a nifty formula that means the amount of heat needed to increase the temperature of a food depends on a specific heat constant of a material. OK, hold that thought.

Q is the amount of heat dumped into the food and is measured in joules. M stands for the mass of the food (its weight using a scale), measured in kilograms. Delta t is the temperature difference between where you started (like room temperature) and the food's final temperature (use Celsius, be cool). CP is the specific heat of material, a number that characterizes how much something heats up when you apply specific heat. It's measured in joules per kilogram.

A grand answer machine. Don't know how to find a specific heat or convert these units into other units? Use Wolfram Alpha, a computational knowledge engine that calculates for you. Bookmark it. You'll use it.

Know this: There is a direct relationship between the amount of heat applied and how much the temperature rises, that's all we're saying with this formula.

The message here is to learn what it takes to control variables for consistency so you get the same results every time. Observe and understand how ingredients function. You can't push to the next level in cooking just by switching ingredients on a technique. Learning cooking goes much deeper - understanding how new technologies and science relate to cooking. There has to be a reason to apply the knowledge, not just throw the science at whatever you're doing.

Dave Arnold of the New York bar Booker and Dax gives a terrific demo on how to make a campari and soda. Is there a better way to talk science than showing how to get those crazy bubbles into a cocktail? Dave spent years teaching other chefs how to apply new technologies and techniques; he's a lab master. In another eye-popping demo, he forces coffee into rum using nitrous infusion. This is the kind of stuff we should be showing students to fire the imagination for food science. (I'm advocating the art of the science here, not the consumption of alcohol.)

Cool point: Champagne flutes have low surface area to volume ratio, so they don't lose as much bubbles over time. That means, serve your bubbles in long, slender glasses, not those cuppy glasses in the movies.

Takeaway lesson: The most important innovation in cooking technology is lower-temperature cooking. The real revolution is in temperature control via tools like the immersion circulator. It keeps water accurately heated to a set temperature well below boiling - and that's how you get a perfectly cooked egg - by boiling it longer at 64 degrees instead of 212. Now sous-vide cooking begins to intrigue me. More on that as we move on.

Number of pages of notes taken: 34, an increase of 12 pages over Week 1
(but I rewrite all the math problems to "bake in" the concepts)

Up next: Phase Transitions in Week 3