Food Matters: Science Fare at Cooking School of Aspen
December 28, 2017
TO THE NAKED EYE, it's a soup crock covered with a golden-brown cloak of puff pastry. To David Houggy, president of the Aspen Science Center, the flaky crust over each portion of saffron tomato bisque represents a mathematical formula: three to the sixth power.
"We started with a pound of butter, pounded out flat on top of the pastry dough," Houggy tells our class, gathered at the Cooking School of Aspen demonstration kitchen on a recent evening. That preparation was folded into thirds, rolled out, and refrigerated.
"The first time, you get three layers," he continues. "(The second time), nine layers. You do that six times — three to the sixth power — that's 729 layers of butter! When steam hits it in the oven, water molecules get trapped in those layers and they puff up."
Leavening is just one principle covered during our first lesson in the Science of Cooking, an educational dinner series held on select Thursdays at the Cooking School this winter. In the case of this puff pastry, leavening is achieved through a scientific reaction (steam between layers) rather than an active ingredient such as baking soda. Yet we'll learn about the latter, too. Executive chef Gil Hitzler uses baking soda to bake fluffy blini (tiny Russian pancakes), which he serves as our second course with salmon gravlax, crème fraiche, and caviar.
“Understanding the science behind how something works …you will be a better cook.”
—David Houggy, Aspen Science Center president
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Houggy shares that Hitzler uses baking soda in the blini recipe because it's less leavening than baking powder.
"When you take baking soda — a base on the pH scale — and react it with a little bit of acid, you get carbon dioxide. It gets fizzy," Houggy explains. "The acid neutralizes the base, and CO2 bubbles cause the blini to rise."
Baking powder contains both base and dried acid. "Most baking powder is 'double acting,' which means one of the acids will react with the base at room temperature; the other acid will react with the base when it gets hot," Houggy explains. "By using double-acting baking powder, you get that initial burst of bubbles; then you put it in the oven and get more bubbles."
Of course, without an emulsifier — such as eggs — to trap the bubbles in the pancake batter in the first place, these bubbles would dissipate. We notice this happens when a dish of baking soda mixed simply with vinegar is passed around the room.
The soup also presents an opportunity for chef Hitzler to drop a trick for turning his tomato bisque extra-creamy: Cooking rice directly in the soup before it's puréed. This releases starch, or particles that interrupt liquid flow.
Inside our 14-page handout we find a list of other thickening agents, categorized as starches (cornstarch, potato starch, tapioca, arrowroot, rice flour, all-purpose flour), natural gums (agar or seaweed; guar gum, which boasts eight-times the thickening power of cornstarch; locust bean gum; xanthan gum) and proteins (egg yolk, gelatin, yogurt). Each has different properties that might affect a dish in various ways. For example, pure cornstarch doesn't contain any protein, as flour does, so it creates a "translucent shimmer." This makes cornstarch an ideal thickener for delicate stir-fries and stone-fruit pies because, "it won't cloud the colors." Ah-ha.
Over the following courses — tonight divvied up into five tapas-style plates instead of the traditional Science of Cooking format of three main courses, to showcase as many scientific lessons as possible — we learn about caramelization (kale, shiitake mushroom, butternut squash, and plum cabbage tempura), acidic reaction and emulsification (seabass ceviche with mango vinaigrette), and air suspension (dessert yogurt infused with sparkling pomegranate juice), among others.
In the case of the salmon gravlax, Hitzler cured the fish using a blend of salt, lemon juice and vodka over a period of 48 hours.
"Proteins are strands of amino acids, and they're all tangled up," Houggy explains. "When you cook meat, fish, an egg, those proteins untangle and start to get soft. (Over) long periods of time, they become tender because the proteins are unwinding."
The salt and acid, then, "cook" the fish in place of heat, since these ingredients also denature protein strands.
"But because it's not getting hot," Houggy cautions, "it won't kill bacteria, so you have to be careful." Hence the focus on high-quality fish in raw preparations. ("Sashimi-grade," by the way, is a marketing term not recognized as a barometer of quality by the FDA.)
By the same token, the longer a protein cooks, the more the amino acids tighten, forcing liquid out. (Ever notice the liquid created after marinating ceviche?) So, a steak pulled from a hot grill will bleed if cut immediately.
"If you let it sit, those proteins that tightened up start to relax and the moisture will get reabsorbed," Houggy says. "So, you'll have a juicier steak if you let it rest five to 10 minutes."
Meanwhile, Cooking School of Aspen founder Rob Ittner is on hand to pepper the instruction (split by Aspen Science Center board member Mike Simmons and with assistance from Cooking School teaching chef Susan Thomas), with anecdotes about the science of wine, paired alongside our courses. His big question: What is fermentation?
"Most people think it's making alcohol, but it's not," Ittner says. "It's the chemical process of changing one molecular structure to another molecular structure with the byproduct of CO2 — there are a lot of fermentations that have nothing to do with alcohol."
While each Science of Cooking class covers different principles, all offer a chance to geek out over food. After all, the mission of the 2005-founded Aspen Science Center (increase awareness of science in our everyday lives and, hopefully, foster appreciation for science, according to Simmons) pairs perfectly with that of the Cooking School (share a passion for learning about food through entertaining dining experiences).
"Understanding the science behind how something works makes me appreciate it better, especially in cooking," Houggy says. "If you understand what you're doing and why you're doing it, you will be a better cook. Then you can start to stray from recipes and experiment."
No doubt a worthy goal for 2018.
"Understanding the science behind how something works …you will be a better cook." —David Houggy, Aspen Science Center president
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