Week 9: Baking, Harvard Style

Getting the oven heat just right makes all the difference in pretty little feet for macarons

And so the Harvard online food science class finally reaches my heart's desire, the world of sugar and fat. It makes sense that the course has waited so long to get to this area of interest, since baking involves the concepts of elasticity, viscosity, gelation, emulsions, heat transfer and solubility, all food for thought in the course to this point.

Just what constitute baking? Call it the indirect application of heat to food. In other words, if you've "cooked" ceviche using lime juice, that's not baking. To dig into this further, we learn how the elastic properties of dough are one of the central features of baking. Three things give rise to dough's elasticity and how it changes: 1) the properties of gluten (found in flour) 2) the elastic network of eggs 3) starches and sugars (and how they behave). Viscosity in baking is all about how dough rises and expands. Emulsions are everywhere in baking - in cake batters, cookie doughs, souffles, dessert sauces and even chocolate ganache. Let's not forget those all-important chemical reactions (since this is food science), including release of gases (from chemical leaveners and yeast) and solubility of ingredients, like sugar in water for a simple syrup. What a mouthful, all these concepts of baking.

There are wonderful demos during this week, many of them from Joanne Chang, owner of Flour Bakery in Boston and Cambridge, who walks us through a yellow cake; a good pie dough; pate a choux, pastry cream and caramel for building a croquembouche, and artisan bread with a great scoring pattern on its top. Here's an attempt to capture just a few of the "a-ha" tips from Week 9.

A-Ha!

1) The creaming method is called the creaming method because when you beat air into butter, the mixture turns the color of cream. How did I get through baking & patisserie school without hearing THAT?

2) Why should eggs for a recipe be at room temperature? Because if they're cold, they introduce a temperature difference to the mixture. Same with butter. Adding ingredients that are too cold can break a batter's emulsion; we learned that in school. So the idea is, keep all your ingredients at room temperature (if you have time; I've rushed a few egg whites through for macarons).

3) What's the "3-2 method"? It stands for alternating wet and dry ingredients into a batter. The dry ingredients represent the "3" and the "2" is for the wet ingredients. So you add a third of the dry ingredients, then half the wet, then a third of the dry, then the other half of the wet, and finish with the last third of the dry. Start and end with dry, there's a good chef.

4) Know your acids in the recipe, because they all contribute to the activation of chemical leaveners to release carbon dioxide (and cause leavening). The list: chocolate, molasses, sour cream, coffee, buttermilk, vinegar and lemon juice, to name a few.

5) Did you know: A souffle that has deflated will rise again if you put it back in the oven, where air and moisture will help it expand. Something else to note about a souffle: The base must be overflavored to compensate for its dilution by egg whites and air. Meaning, use more vanilla than you think.

6) Why is a sourdough starter good for croissant dough? It acidifies the dough, which decreases the dough's elastic modulus. All I know is, it's always easier to roll out than just plain croissant dough. As it turns out, when you lower the pH of the dough (by adding sourdough starter), the glutenin molecules become more charged, so they repel each other, which lowers the strength of their interaction and the gluten network (glutenin and gliaden combine to form the gluten network) and the dough becomes more tender. Like I said, the dough is easier to roll out if you add a sourdough starter.

7) There are 2 kinds of browning reactions that give those lovely colors and tastes to baked goods: caramelization and Maillard Reaction. Caramelization causes browning when sugar is heated and the sucrose molecule separates into fructose and glucose. The caramelized result tastes buttery and nutty. This occurs at about 165 degrees Celsius or higher. The Maillard Reaction happens as heat is applied and sugar molecules react with amino acids in protein molecules. This happens above 120 degrees Celsius. Good old Dulce de Leche is an example of a Maillard Reaction of a milk and sugar solution. So is a browned steak.

My Favorite A-Ha Moment of the Week: How to make a better chocolate chip cookie without the creaming method. This method from America's Test Kitchen is so good, it deserves a separate post, so visit the chocolate chip cookie here.

Equation of the Week: If I understand my notes correctly, we used formulas related to the concepts that have been covered throughout this course, i.e., we repurposed the elastic modulus, the formula for determining cross-link distances and so on. Importantly, we did calculate the exponential growth of yeast. It involves huge numbers so you need one of those exponential calculators to do the math.

I'd rather build a croquembouche.

Final Week: Fermentation!