September in Boston is that special time when hordes of undergrads and graduate students saddled with heavy messenger bags move back in to their dorms and apartments, as well as the local Boloco/Starbucks. Hip to the times, Harvard offers a curriculum that reflects the food experimentation occurring in restaurants and bars around Boston and Cambridge with a course titled “Science and Cooking: From Haute Cuisine to the Science of Soft Matter.” Chef and food expert lectures related to the course are open to the public weekly from September to December.
Last Monday, I headed to campus to hear Joanne Chang speak on “The Science of Sugar,” a subject she’s more than acquainted with as the force behind the local Flour Bakery + Cafe. Chang has authored two cookbooks featuring recipes from Flour and will debut a new book next April: Baking with Less Sugar. After an intro from Harvard faculty describing cooking as the “control of phase transitions,” Chang took the cooktop to discuss the uses of sugar in a recipe, besides adding sweetness.
Turns out, sugar works hard to create air pockets in a fat like butter, making cakes light and fluffy. It attracts water molecules, allowing packaged cookies a long grocery shelf-life. It lowers liquid’s freezing point (as when making sorbets and ice cream) and increases its boiling point. It stabilizes egg foams, important for meringue, and inhibits gluten development. It aids in browning, a la the Maillard reaction, and helps pastries get crispy.
Chang explained the stages of sugar when heated with water. It goes from thread stage through soft-, firm-, and hard-ball to soft-crack, hard-crack, and caramelization. In between thread stage and caramelization one can make fudge, caramels, marshmallows, taffy, and lollipops, respectively. At caramelization, one can mix in nuts to create praline or, as Chang demonstrated, make spun sugar. The end of the lecture featured the construction of a croquembouche, pastry balls covered in thin, ethereal caramel threads. According to Chang, the secret is in the wrist flick.
The true finale of the night was our sugar education in action via a crispy sugar cookie and a dollop of thick buttercream drizzled in light caramel, confirming that I am, in fact, a gustatory learner.