Growing up with Kitchen Chemistry (and my abiding love for Harold McGee)
When I picture my mother’s kitchen at home in California, I see sunlight streaming through the window above the sink. I see her red Kitchen Aide, the white stovetop, and the oven and fridge bookending the narrow galley kitchen. And on the bookshelf above her kitchen counter, I see a familiar red book.
This book is one of the few books I know is on my mother’s kitchen bookshelf, and surprisingly, it’s not a cookbook. Instead, it’s Harold McGee’s On Food and Cooking, which is easily one of my favorite chemistry books of all time.
Harold McGee has been a fixture in my mom’s kitchen for as long as I can remember. We frequently referenced him during our kitchen adventures when I was growing up. Want to know why whisking eggs and oil makes a nicely emulsified mayonnaise, while whisking water and oil just makes a quickly-separating mess? Look in Harold McGee. Want to know why melted chocolate siezes and gets really gross if you add too much liquid? Check Harold McGee.
Sometimes, it felt like we were on a first-name basis with him. It wasn’t just, “look it up in Harold McGee,” but instead, “ask Harold!” It was as if he was a trusted friend and teacher, standing by to answer even our most mundane kitchen chemistry questions.
The answers often straddled the border between simple and magical, and if you kept reading, you almost always learned something new. Mayonnaise forms a nice emulsion, for example, because egg yolks contain proteins and other molecules that coat oil droplets and help keep them suspended in water. But did you also know that when you beat a single tablespoon of oil into a mayonnaise, it gets broken up into something like 30 billion tiny droplets?
When I started thinking about topics for this week’s food chemistry carnival, I pulled out my copy of McGee and turned to the section on pastries, thinking it would be fun to write about what exactly it is that makes the perfect pie crust (which, it seems, is a popular topic this week – for the record, my favorite is the Cook’s Illustrated vodka pie crust!). But as I started flipping through the book, getting sidetracked by countless other tidbits of food-related information, I realized that I really just ought to write about On Food and Cooking itself.
Flipping through the section on breads and pastries provided a perfect reminder of why I like this book. Within just a few short pages, I ran across SEM (scanning electron microscope) images of wheat grains, chemical equations describing how carbohydrates react, and schematic drawings of how gluten chains bind together to form springy, elastic bread dough, all explained with easily-digestible text. The breadth and depth of the science in this book is amazing, yet McGee’s writing makes it approachable even for food chemistry novices.
One of the brilliant things about McGee’s approach to kitchen chemistry is that he focuses on the big picture. He doesn’t get bogged down in the exact structure of the surfactants in eggs or the proteins in gluten or the the fats in cocoa butter, but instead shows them as schematic diagrams (like spheres, or springy coils) that highlight the essential behavior without distracting you with the details. As he writes in the introduction, “in cooking it’s generally a molecule’s shape that matters, not the precise placement of each atom.”
Sometimes, as a chemist, I find these simplifications a little frustrating – for example, when McGee writes that glutenin (one of the proteins in gluten) is a long, coiled chain, my chemist brain wants to know if he means that it’s alpha-helical, or if it’s a more amorphous coil. But I think that this sort information is really beyond the scope of his book, and omitting it makes On Food and Cooking more accessible to the casual cook. Besides, if I really want to know, I can always ask the internet – did you know that people have actually done FTIR experiments to monitor changes to gluten’s secondary structure during mixing?
The other thing I love about On Food and Cooking is that it isn’t just about the chemistry of food. McGee includes tidbits about food’s history, as well, and provides broad overviews of the similarities and differences between different types of related foods. I think of this book as equal parts encyclopedia, history book, and science text.
Now, as a graduate student living on my own in Wisconsin, I have my own copy of McGee. It’s sitting happily on my kitchen bookshelf, nestled in among my favorite cookbooks. And it’s once again there to spark my curiosity and answer all of my questions about why my food does what it does.
So thanks, Harold, for showing me that chemistry is everywhere, even in the food I eat. And thanks, mom, for giving chemistry a place in our kitchen.