UC Press Blog

By Patricia B. O’Hara, author of  Food Chemistry in Small Bites

Some projects take a long time to be fully baked, and Food Chemistry in Small Bites is no exception.  This textbook, intended for general studies students who want to learn a bit about Cooking and Chemistry, grew out of a course I have been offering for the past decade. 

How did a Professor of Chemistry, Biochemistry, and Biophysics come to learn and teach about Food Chemistry and Molecular Gastronomy? Like most things here at Amherst College, it began with the students. In 2012, I had in interim role as Dean of First Year Students. In that capacity, I decided to host liquid nitrogen ice cream parties in each of the seven first year residence halls over the first semester. Yes, that means ice cream for 500 hungry students. Conversations with two particular first year students at one of these events led to my sponsoring a special topics course in Molecular Gastronomy the next spring.  Modeled after Harvard’s Science and Cooking course, we worked our way through the online syllabus but redesigned the course to have a greater emphasis on my interests: chemistry and biochemistry. The small group quickly grew to more than a half dozen students, and by the end of that spring semester, we had a fully developed syllabus and an outline for several labs. 

That special topic course has morphed into a regular course offering, “CHEM 100 Molecular Gastronomy: From Test Tubes to Taste Buds.” Nearly a hundred students compete for the precious slots that are limited by spaces in the culinary lab. Topics such as sensory perception, chemical structure, acid base chemistry, fermentation, and oxidation are brought to life using culinary examples.  Teaching chemistry by using examples from the kitchen lowers the barrier to learning by making the science familiar—relatable—and sometimes edible. 

The content of this course became the foundation for Food Chemistry in Small Bites, which is divided into three sections: 

• Part I: Informing, with chapters on the chemical structure of our nutrients and how we perceive flavors and fragrances
• Part II: Transforming, covering how these nutrients are transformed by heat, pH, pressure, fermentation and the large role emulsions play in sauces, vinaigrettes, condiments and desserts
• Part III: Reforming, which considers the Future of Food using the scientific principles presented earlier in the text and offers a Sampling of Lab Experiments.

Drawing on lessons from the course, I structured the text as a guidebook for a journey students will take into the world of Food Chemistry. They are told that, like any expedition to a foreign country, they first need to learn the vocabulary and some of the local culture. In chemical terms, this means they need to understand the underlying molecular structure of the basic nutrient groups: fats, proteins, and carbohydrates. Emphasis is placed on the shared theme of simple monomers (sugars, amino acids, and fatty acids) combining to form more complex molecules (carbohydrates, proteins and fats). 

Because interactions between atoms and molecules are fundamentally electrical in nature, charge distribution dictates many of the physical properties that are altered as food is prepared for consumption. In this text, molecular structures are illustrated with line drawings that show the atomic connectivity overlaid by electron charge distribution images that highlight polar regions of unbalanced positive and negative charges or and nonpolar regions where charges are balanced. With this background, students can see why a mixture of oil and vinegar separates and why an emulsifier can keep the two phases from separating. They also discover how food molecules interact with our sensory apparatus.  The flavor of food, which integrates taste and smell, begins with the recognition of the shape or charge of a molecule derived from food by receptors in our nose and mouth. 

With these foundational concepts, students can consider how these basic elements of food are transformed by different cooking methods and through acidification, fermentation, and oxidation. In each process, and by cooking in the lab, students see how these different processes rearrange or disrupt the chemical bonds of each nutrient group, or even transform them.

The students close out their journey by considering challenges and solutions to food production in the future. As I reveal in the book, food chemists have shown us how waste streams can be recovered using enzymes. Bioengineers have shown us how to use natural gene editing tools to insert heat resistant genes into crops. And food chemists have created plant-based sources of protein that will help us reduce our reliance on environmentally costly meat-based protein sources. As I’ve seen in my course, students walk away with both a deeper understanding of chemistry and a better appreciation for the meal on their table.