Week 4 of our food science course focused on elasticity in food, mostly in candy-making and cooking meat. The candy-making part focused on Bill Yosses, the White House pastry chef. There were six videos of Yosses making various things, including strudel, a blown sugar “glass” apple, and an over-the-top dessert that I assume is the kind of thing that gets served to people at state dinners. This dessert had at least a dozen different components, some of which were suspended in a candy sphere designed to melt and release them on top of other components. It was very impressive to watch, and yet when it had melted, the whole thing looked kind of gloppy and unappetizing.
Anyway, once again, six videos of one guy cooking was way too much. Besides that, somehow neither of us found this material very compelling. Arne was bored because he works with elasticity on a much more involved level every day. So we wound up never getting around to doing the lab, which consisted of placing weights on food before and after cooking to ascertain any changes in elasticity. So I have no pictures of it for you.
The one thing in this week’s presentations that I found fascinating didn’t have a lot to do with elasticity, and it was America’s Test Kitchen‘s method for mimicking dry aging in an oven-cooked beef roast. Their plan is to activate the enzymes that work in meat over the process of dry aging: calpains and cathepsins. These enzymes act to physically weaken and break down muscle fibers, increasing tenderness. They act slowly at refrigerator temperatures (which is why meat can be aged for as much as a month), but faster at higher ones, until the enzymes are killed by heat at 122 degrees Fahrenheit.
To mimic the action of dry-aging, Dan Souza of America’s Test Kitchen – one of our favorite presenters in the course – seared an eye of round roast, then placed it on a rack (for optimal circulation) and roasted it at 225 degrees for one and a half hours, until the internal temperature reached 115 degrees (just right for the enzymes’ action). After that he turned the oven off, letting the internal temperature rise slowly to 130 degrees. He used an entertaining method to demonstrate the meat’s tenderness compared to a conventionally cooked roast, lifting slices of both with weights tied to them. The slow-roasted one could barely be lifted, falling apart instantly. It also was much more evenly medium-rare.
I really want to try this method!
So, on to Week 5, Diffusion and Spherification. This was probably my favorite week so far. There were even more videos from a single celebrity guest – EIGHT from Jose Andres, legendary Spanish chef and modernist cooking pioneer – but his videos were beautifully edited and presented (and not too long), and Andres himself is a dynamic, entertaining, and informative speaker. Okay, there still might have been one or two more than necessary, but we were delighted to watch him make a magical dish in each of those videos: caramelized clementine skins stuffed with sorbet; truffles of creamy strawberry mousse with hard-frozen shells; delicate steamed coconut “buns” made with methylcellulose, from plant cell walls, instead of flour; feta ravioli with glass-clear skins of gelled feta brine; “lemon chicken” with tiny balls of spherified lemon on caramelized chicken skin; Parmesan poached eggs where the whites were replaced by gelled cheese water. Gorgeous, amazing, complicated, cerebral food.
All of this was informed by very interesting scientific presentations. We learned how amino acids in proteins unfold and link when exposed to heat, as when you cook an egg, or in response to acidity, as when you “cook” fish in lime juice to make ceviche. We also learned about the chemistry behind the iconic modernist technique of spherification – as with the lemon balls in Andres’ lemon chicken – which I have tried in the past without great success. Now I suspect I left the balls in their calcium bath too long, so the calcium diffused too far into the center and they gelled through instead of remaining liquid on the inside.
The lab we chose to do was simple enough: time the diffusion of lime juice into fish by removing pieces of fish from their lime-juice bath at regular intervals, cutting them open, and measuring how far into the center the “cooked” part went. In practice, it didn’t go so well.
We found gorgeous fillets of black cod at Whole Foods, bought one that weighed almost a pound, and used it for our experiment (and for our post-experiment reward – a big bowl of ceviche). Maybe black cod is a particularly dense fish, but for whatever reason, the acid diffused in a couple of millimeters and seemed to go no farther, except in the case of one mid-experiment outlier, which we figure must have had some cracks in the flesh that let the lime juice in. Or something.
While we waited for time to elapse between measurements, I made ceviche – not from EdX’s recipe, but from Mark Bittman’s recipe from “The Best Recipes in the World” with the bell pepper removed and avocado and onion added. The recipe is at the bottom of the page.
In any case, we reported our bizarre results and retired to the dining room with a bowl of way more ceviche than two people need. (Turns out the experiment didn’t use much of that pound of fish.) The black cod was very mild, moist, and rich – easy for me to swallow – and somehow we ate that whole bowl of ceviche, plus a pile of crackers and tortilla chips. I mean, it doesn’t keep that well, right? We had to eat it all!
Stay tuned for week 6 – Heat Transfer – and its Molten Chocolate Cake lab!
Simple Ceviche with Avocado
Serves: 4 to 6, or 2 diners with no self-control Time: 30 to 45 minutes Hands-on: 10 to 20 minutes
1 pound extremely fresh fish or sea scallops, cut in 1/4-inch dice
1 teaspoon minced lime zest
1/4 cup fresh lime juice
1/2 teaspoon salt, plus more to taste if desired
2 tablespoons minced red onion
1/2 teaspoon Cholula, Tabasco, or other hot sauce
1 ripe avocado, in 1/4-inch dice
1/4 cup plus 2 tablespoons chopped fresh cilantro
Toss the fish with the lime zest, lime juice, salt, and onion. Let marinate in the refrigerator for 15 minutes. Remove a piece of fish and cut in half – if it’s opaque most of the way through, I consider it done. If you want it more “cooked,” let marinate 5 to 10 more minutes.
Stir in the hot sauce, then the avocado and 1/4 cup cilantro. Taste for salt and add more if desired. Garnish with the 2 tablespoons of cilantro. Serve with tortilla chips and/or Saltines, and a bottle of Cholula or other hot sauce for each diner to spice up their own portion. Devour.