Sourdough Science in Chemistry of Cooking

Upper School students got some hands-on experience with the process of fermentation in their Chemistry of Cooking course when Food Service Manager and master baker Zac Maness combined forces with teacher Gigi Mathews to make bread from sourdough starter.

In classwork leading up to visits from Maness, Mathews had provided students with an overview of how microorganisms like bacteria and fungi are common in making a range of food products. Looking as far back as 7000 BC, students learned microorganisms were part of brewing beer and bacteria and fungi have since become ubiquitous in food staples around the world.

Students learned that fermentation requires cellular respiration, a process by which organisms use oxygen to break down food molecules to get chemical energy for cell functions. When oxygen isn’t present, the living cell obtains energy by breaking down glucose and other simple sugar molecules, which produces less energy than the process of cellular respiration when oxygen is present.

Keeping what they had recently learned in mind, students worked in groups to make sourdough bread starter. First, they mixed flour and water in a container, where the enzymes in the flour convert large starch molecules into simple sugars—a perfect fuel for microbial reproduction. Yeasts and bacteria from the environment then fed on the sugars to produce lactic acid, which acidifies the starter, kills bad microbes and combines with acetic acid to give sourdough its characteristic tangy flavor.

Maness visited the students in their classroom when they made their starter and used some of each group’s offerings to make bread dough, which he returned to the class to provide students with direction on forming their loaves. Maness directed his student bakers to handle their dough as minimally as possible for the best results when shaping their loaves in small groups. Once they formed the loaves on their tables, students covered them with plastic to rest while they sifted flour onto proofing baskets, which Maness collected at the end of class.

The following day, Maness returned with the students’ loaves freshly baked from the oven. He pointed out loaves that worked out well, as well as those that didn’t. Students then sampled slices of their labor—topped with some fresh fruit compote they had made for class a few weeks earlier.

Mathews shared, “I was so impressed by the amount of focus the students had as they took care of their sourdough starter. Even before class started, they were in the classroom feeding their starter. They were all in from the beginning and it was shown by the delicious bread each group produced. Their enthusiasm was wonderful. The leftover starter was distributed amongst interested Parker faculty and staff so the legacy of this particular class will live on in their sourdough starter! And wow—Chef Zac! His dedication to his craft and to our students was shown in the immense amount of time he took out of his schedule to share his knowledge and expertise with us. He is truly a gem.”

Parker thanks Matthews, Maness and the entire Quest Food Service team for giving students this unique opportunity to explore the science behind breadmaking firsthand.

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Francis W. Parker School educates students to think and act with empathy, courage and clarity as responsible citizens and leaders in a diverse democratic society and global community.