Science + compost = cake

February 18, 2011

(Gazette photo by Rebeca Oliveira) Colette Chien, Annie Tremblay, Bill Perkins, Lucie Tremblay, Margaret Connors and Varsha Perkins show off their kitchen tools: spades, rulers, clipboards and thermometers, during a chemistry/home economics experiment baking chocolate cake in a 20-foot-tall Arboretum compost pile.

Kids cook in compost

JP SOUTH—Legs sticking straight out, Lucie Tremblay had dived headfirst 30 inches into the top of a 20-foot-tall compost pile, trying to figure out exactly how deep she should bury the chocolate cake so she and her science class could come back to eat it the next day.

As the Feb. 13 science class showed, home-schooling can be unorthodox.

Tremblay, and her sister, Annie, along with classmates Colette Chien, and Varsha Perkins, all 11 years old, are learning about chemistry from teachers/parents Margaret Connors and Bill Perkins by using the exothermic (heat-producing) reaction in compost piles at the Arnold Aboretum to cook pasta with red sauce and a chocolate cake.

They previously poached eggs in compost: “Those were the best eggs I’ve ever had,” Bill Perkins, Varsha’s father, told the Gazette before the experiment started last Sunday, Feb. 13. “They were almost custard-y. The texture was excellent.”

Compost piles can reach 160 degrees, science teacher Connors told the Gazette—but would there be a significant temperature difference between the wood chip and leaf piles? Would pit depth yield different temperatures? And how long should they bury their vacuum-sealed food so it would be thoroughly cooked?

“It’s science time!” Connors called to her students when it was time to start digging.

Traditional recipes said the cake should bake 30 to 40 minutes at 350 degrees. The temperature outside, according to Annie Tremblay, was 39 degrees. The highest temperature recorded, at 18 and 36 inches deep in the wood chip pile, was 120 degrees. The class pulled out a clipboard and calculator to figure out how long the cake should cook, based on results from the earlier egg experiment. The class decided to taste-test on Monday, around 5:30 p.m.

“Everything gets recorded in a scientific study,” Connors said as the students dug pits and took temperature readings on Sunday.

After half an hour of unearthing on Monday afternoon, the class tasted the cake: “It was the perfect lava cake, slightly crusty around the edges and pudding-like in the middle,” Connors said. The class ate it right there, fresh from the compost.

The pasta with red sauce, however, was a “disaster,” Connors said.

During the earlier egg experiment (cooking time: 48 hours) Connors contacted JP resident Eva Katz, a contributing editor at America’s Test Kitchen, to ask if the egg would be safe to eat. According to Connors, Katz made a connection to a type of French cooking that is similar to compost cooking—a slow and low-temperature approach to cooking called “sous-vide,” French for “under vacuum.”

“Cooking sous-vide in your back yard compost could be an interesting concept,” Katz said, though she admitted she didn’t know enough about the methodology to guarantee safety. Sous-vide was first used in home kitchens in France in the 1970s and traditionally is the process of cooking vacuum-sealed food in a low temperature water bath.

After the original egg experiment, the students expressed an interest in doing more compost cooking, possibly even writing a recipe book—“Cooking with the Bugs,” “Easy-Bake Compost Oven,” or “Compost Cooking” were suggested titles.

The science class has previously studied the health of Bussey Brook and done body studies with “drawings of all your organs,” Lucie Tremblay said. They also cared for a baby squirrel named Pistachio, who was very fond of watermelons, Chien said. They are currently studying the possible effects of a diet laden with fast food on children.

Besides science and social studies, the students also study reading and writing, Greek mythology, vocabulary, geography, Latin, home economics, and are running a long-term project about opening and running a restaurant, among other topics.

The kids have been home-studying together for under a year, though they have known each other for a few years, Connors said.

“The kids were either too stressed or bored with conventional school. They love home schooling,” Connors said.

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