(Jan. 5) In all your culinary training, you probably never were taught to squirt vegetables from a whipping cream dispenser onto an entree.
But that was then. This is a new culinary era.
If you purée a vegetable (or fruit or any savory or sweet item), pass it through a sieve, add a stabilizer — like gelatin, egg whites or any other thickening agent — and pour the liquid into a whipping cream dispenser and add a nitrous oxide charge, you end up with foam. It’s light and airy with intense flavor. The technique is gaining momentum among high-class establishments.
Ultimately, you can thank renowned chef Ferran Adria of El Bulli restaurant, in Roses, Spain, for developing the foam concept — also called espuma — in the late 1990s.
He decided to create a new type of cuisine using his whipping cream bottles and chargers manufactured by ISI GmbH, Vienna, Austria.
“Our distributor in Spain informed us that he was selling our bottles at his restaurant,” says Rick Agresta, president of ISI North America Inc., Fairfield, N.J. The distributor paid Adria a visit and discovered he was creating culinary foams.
The idea of passing denser elements than cream through the container led ISI to develop a new unit to handle thicker contents and hot liquids and give a more directed flow for decorating with foam, Agresta says. The result was the ISI Gourmet Whip container, which also can be used to whip cream. It’s the leading piece of equipment to accomplish espumas, experts say.
BACK IN THE U.S.
Six years ago, Rick Tramonto, executive chef at Chicago’s Tru restaurant, traveled to Spain and visited El Bulli restaurant, where he had clam water foam. “I was intrigued by it. I started to do research on (Adria) and his cuisine,” he says.
A few years later, Tramonto returned to Spain and met Adria, spent time with him in his kitchen and learned more about espumas.
Tramonto first made espumas at Tru with fruits and vegetables. Then he tried herbs and moved on to cheese and foie gras.
“(The foams) add color and concentrated flavors that are feathery light,” he says.
He featured warm lobster foam for 600 people at the Epcot International Food and Wine Festival. Orlando, Fla., in October, “and they went wild over it. It was the talk of the event,” he says.
Tramonto is careful not to go crazy with foam. At Tru, he offers four menus and only has one item on each menu with foam. “It’s another toy in the sandbox. My job is to keep up on new techniques and apply them in my cooking in a balanced way to keep my food on the cutting edge …,” he says.
Last summer he featured tomato basil salad topped with garlic foam and fresh olive oil. He also has topped potato chips and canapés with red beet espuma and stuffed squash blossoms with basil foam. He likes saffron espuma for its bright yellow color and serves it on calamari salad. Citrus foam works on scallops or on steamed asparagus, he says.
HERE’S HOW
Agresta with ISI North America and Nancy Hartmann, marketing manager, offer the espuma-making details.
First, purée the ingredient you want to change into foam and pass it through a sieve to remove seeds, skin and other chunky elements. Then transfer the liquid to the whipping bottle and add a stabilizer to help it maintain consistency and hold its shape when it’s whipped, Hartmann says. The stabilizer or thickening agent could be gelatin, egg whites, potato starch or agar-agar, to name a few.
To blend in the stabilizer, you may have to heat the food you’ve strained before you add it to the bottle. For example, if you use gelatin, you will need to heat it to melt it into the mixture, Agresta says. Then chill it in the bottle in the refrigerator for two to four hours before you give it the nitrous oxide charge.
After you give it the nitrous oxide charge, shake the bottle two or three times to engage the gas in the liquid, Agresta says. The liquid turns to foam as it is driven out of the bottle and aerates.
You may have to give the liquid more than one nitrous oxide charge, Tru’s Tramonto says. Some vegetables take two or three charges. He recommends experimenting, and if the foam doesn’t hold up with one charge, add more.
Not all items you turn into foam require a thickening agent, says Grant Achatz, executive chef at Trio restaurant, Evanston, Ill.
He studied the technique under Adria of El Bulli for a few weeks in the summer of 2000. Quince, for example, has enough natural pectin in it that once it is poached and processed, it will hold up as foam without gelatin.
When he turns celery root into espuma, Achatz adds a little cream to the purée and finds it needs no other thickener.
The type of thickener you add to a purée depends on whether you plan to serve the foam on hot or cold items, he says.
Gelatin, for example, is thermo reversible. When you prepare and refrigerate it, it becomes solid. But when you place it on the stove it becomes liquid. The same will happen if you use it in a foam. If you apply foam that has been thickened with gelatin to a hot item, the foam quickly turns to liquid.
If you plan to apply the foam to something hot, use a natural starch like potato or natural pectin, which is not reversible and won’t melt, he says.
“If I want to make red wine foam and I want to serve it hot, I need to look at (thickening agent) sources. Agar-agar is a vegetable-based gelatin that is not thermo reversible. When it’s heated, it doesn’t melt, unless it’s extreme heat,” he says. Also, the clear nature of agar-agar doesn’t interrupt the color of the red wine.
AMAZING RESULTS
Katsuya Fukushima, chef at Café Atlantico, Washington, D.C., has 10 foams on his menu. He works for executive chef Jose Ramon Adres, who owns three Washington, D.C., restaurants and worked for Adria at El Bulli for several years.
Following in the footsteps of his boss, Fukushima also traveled to Spain two years ago and worked with Adria for a season.
Fukushima makes a pina colada dessert with vanilla-infused rum in a martini glass topped with coconut sorbet, pineapple and a coconut espuma.
For a feathery light potato mouse, he simply squirts potato espuma in a sherry glass and adds a dollop of caviar and drizzle of vanilla oil.
But one of his most impressive espuma applications begins with an egg white-based corn purée foam. He squirts about five puffs of the corn foam into the bottom of a soup bowl with some sautéed chanterelle mushrooms and drizzle of olive oil. “I sprinkle crushed corn nuts on top to compliment the foam, and that goes to the table,” he says. Then the server ladles hot foie gras soup into the bowl on top of the espuma and mushrooms at the table. “Once the soup hits the cold corn floating islands, they puff and float around in the soup,” he says. Guests can drink the soup or pick up the floating espuma corn.
You also can make light sauces and soups with the ISI Gourmet Whip and keep them warm in the bottle, which means you can travel with your sauce and not have to reheat it, Agresta says.
That makes it great for caterers, as it will keep sauces warm for six hours without forming a skin on the surface.
The number of applications you can get from one batch depends on the contents, but aerated foam has more volume than the item you initially place in the bottle, which gives you a lot of mileage and allows you to use less food and therefore serve fewer calories. “From a cost standpoint, you’re spreading your food out,” he says.
