Students Have Chocolate-Covered Science Fun

Upper School students in the Chemistry of Cooking class learned the art of tempering chocolate thanks to a visit from confectioner Sarah (Levy) Imberman ’99 and her partner.

Prior to this visit, students in Gigi Mathews’ Chemistry of Cooking class learned what makes chocolate so special and delicious. She introduced them to the fats associated with chocolate, noting that triacyglycerol (a backbone glycerol bound to three fatty acids or acyl chains) is a major component of chocolate. She pointed out that the melting point of chocolate is linked to the triglycerides that compose it, and the more contact carbon chains of triglycerides have within a sample of chocolate, the higher its melting point.

Mathews encourages students to think about cocoa butter molecules like Lincoln Log building blocks: There are many ways for the molecules to come together, but some configurations are more stable than others. Bringing chocolate to the proper working temperature while making sure the crystalline structure within the cocoa butter is stable results in a more “tempered” chocolate.

Tempered chocolate exhibits a shiny, glossy surface; has a creamy mouthfeel; breaks with a satisfying snap; melts less easily on your fingers; and sets up beautifully for dipped and chocolate-covered treats.

Visiting chef Imberman and her Chief Operating Officer Alexa Sindelar know tempered chocolate very well, as it is one of the primary ingredients in many candies they offer through their business. When Mathews invited this pair to demonstrate the process of tempering chocolate for her Chemistry of Cooking class, they were happy to help.

Imberman demonstrated the multi-step tempering process each student group would replicate as part of that day’s lab, while Sindelar helped set up each student’s station. This process entailed first melting a specific amount of high-quality cacao pistoles to 122–131 degrees Fahrenheit, transferring a portion of this mixture to a holding vessel, adding more cacao pistoles to the melted chocolate, stirring them until they fully dissolved and the mixtures reached 82–84 degrees Fahrenheit, reintegrating the reserved portion of melted chocolate into the primary bowl until the mixture reached 88–90 degrees Fahrenheit and adding 1% of the total chocolate weight of Mycryo™ Cocoa Butter. Imberman pointed out that the Mycryo was the secret ingredient, which started a chain reaction resulting in perfect molecular crystallization, also known as tempered chocolate.

As students worked in groups to follow the instructions for tempering their own chocolate, Imberman and Sindelar went from station to station, offering advice and assistance. Digital thermometers, hot plates and towels were on hand to ensure students could reach the correct temperatures at each step of the process, and they took turns stirring and taking measurements of their mixtures.

With their tempered chocolate ready, students then used spatulas and Imberman’s time-tested “dunk, pump, tap and slide” technique to coat marshmallows, graham crackers and strawberries.

As a special addition to this lab, this culinary duo pre-printed Parker’s logo in tinted cocoa butter onto transparent transfer paper and demonstrated how to add the logo to the students’ dipped cookies and graham crackers as simply as a temporary tattoo.

Parker thanks Imberman and Sindelar for sharing their time and talents with these students. More about their work is available here.

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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.