Hitting the Daily Double

Chris Styler - March 2005

Editor-at-large/restaurant consultant Chris Styler, aka Dr. Knützenboltz, tells you everything you need to know about combi-ovens.

Dear Dr. K: Science has never been my strong suit. Can you explain a combi-oven to me?

A: It's really pretty simple. The "combi" in combi-oven comes from combination, and that's exactly what these units do: cook in several different modes and, most important, in a combination of modes. Set to steam mode, a combi-oven works like a traditional pressure steamer. In convection mode, the unit works like a typical convection oven, perfect for roasting and baking. In combination mode, however, the technology delivers the best of both worlds--forced air convection cooking combined with steam. The amount of steam (and therefore humidity) introduced into the oven is adjustable, which gives chefs the ability to control how much or how little steam is used each time the oven is put to work.

Roger Friedman, executive chef of Cleveland Range, puts it this way: "The combination of hot air and steam is, for many, many things, the best way to cook. The steam helps keep foods moist and colors bright. The convection element browns quickly."

The melding of steam and forced hot air means more than moist browned foods; it means quicker cooking foods. "There's a tremendous amount of energy in steam," Friedman states.

"Water boils at 212 degrees, but the steam it gives off has 870 more BTUs than the boiling water itself. I can cook a pork tenderloin in 10 minutes." He also asserts, "Cold foods, and cold pans for that matter, are like a magnet to steam. The outside of the tenderloin turns opaque a minute or two after it's put in the oven. Cooking in combi-mode is almost like searing."

In Manhattan, chef de cuisine Xavier Mayonove of Jean-Jacques Rachou's LCB Brasserie, whose kitchen boasts the first two SCC 101s from Rational in the country (the SCC stands for Self Cooking Center), puts his combi-oven through its paces every day, during both service and preopening prep time. "It's cheaper and easier to blanch all our vegetables with the oven set to steam mode than it is in boiling water," Mayonove states. But during service, it's combi-cooking all the way. Mayonove, with his ovens in combi-mode and set at 25 percent humidity, blasts through a 3 1/2 pound chicken in 35 minutes. "They're nice, juicy chickens," says Mayonove, who uses the same settings for cooking fish to order. Mayonove expects that his Rational ovens will continue to be more important as he moves closer to his projections of 600 to 800 meals per day and when operating hours expand. "When we go to brunch and breakfast, we'll use the combi-oven for croissants."

Most manufacturers offer combi-ovens that are, in one way or another, programmable. That is, by using factory-installed settings, downloading additional settings from a manufacturer's Web site, or configuring them yourself, you can set your combi-oven to switch seamlessly from one mode to another. Keith Coughenhour, executive chef of Pittsburgh's Duquesne Club, uses his Blodgett combi-ovens in all three modes and takes advantage of their programmable cooking options. For example, push "chicken" on the Blodgett's touch pad, and you'll get a burst of steam cooking, which boosts the temperature quickly and starts to render fat from the birds. From there, Coughenhour states, "It's 20 percent steam and 80 percent dry for a while, then on to all-convection cooking to really crisp up the skin."

Geert Piferoen, director of research and development for cooking equipment and corporate chef of Vulcan Hart, has programmed a Hart combi-steamer oven to take preformed rolls from a frozen state through proofing and baking, all with one touch of a button. First, Piferoen thaws the rolls in convection mode at room temperature (unheated) with a low-speed fan. When defrosted, the rolls are proofed in combi-mode with 5 percent steam at 90 to 100°F, with the fan at half speed. Finally, the rolls are baked in convection mode at 300°F, with a blast of steam and higher heat at the end to crisp them up. In addition to consistency, there are other advantages. "I don't have to move sheet pans from one place to another," states Piferoen, citing one.

Dear Dr. K: Now that we've got that out of the way, do I need one?

A: Friedman sees sales growth in combi-ovens in schools, universities, and other institutional environments but feels that the day when independent restaurants will make the leap to these pricey units is not that far off. "They've been in Europe for 30 years or so, even in small kitchens. A lot of those kitchens are shoe boxes, so they saw the advantages of an oven that works as three appliances early on. I think people in the States don't know about the technology and are scared of the price tag. But you have to remember you're getting three pieces of equipment in one." Friedman claims that even people who are converts to combi-cooking should explore the possibilities further. "Cook everything you're currently cooking in a convection oven in combination mode at least once," he urges. Most chefs and bakers are familiar with the benefits of adding steam during bread baking, but, according to Friedman, there are benefits for other baked goods. "Pie crust is flakier because of the steam. Puff pastry rises better," notes Friedman. "And cookie dough baked in combi-mode gives you a chewy cookie."

Coughenhour has also found combi-baking a sweet proposition. "Cheesecake, crème brûlée, and crème caramel all benefit from a little steam and some dry heat."

Depending on what you're cooking and in what quantity, there are advantages to combi-cooking other than better quality finished product and quicker cooking. Chefs agree there is less shrinkage of expensive proteins when these ovens are used in combination mode. "It can mean an extra slice out of each prime rib," states Friedman. "More slices mean more revenue. Plus, in my experience, it's a better prime rib, and who knows what that means in terms of repeat customers?"

Coughenhour, who has also seen a prime rib yield more sales dollars, wouldn't use anything but combination for his foie gras terrines. "Less shrinkage, definitely. And less shrinkage equals lower food cost." Coughenhour cites some nutritional advantages as well, like the reduced fat in the grilled cheese sandwiches for the employee cafe when they are cooked in convection mode.

Piferoen likes the fact that adding steam to the oven helps keep the interior cleaner, too. On the basis of his own experiments, he claims that foods cooked in combination mode undergo 24 to 28 percent less shrinkage than in a convection oven. "I could never have a kitchen without them. Ninety percent of the restaurants in Europe have them, even those seating 50 to 100," he points out, backing up Friedman's claim that combi-ovens are the next big wave in smaller, independent restaurants. Piferoen stresses the excellent cook-and-hold properties of combi-cooking. "They're so much more advanced than holding boxes kept hot with Sterno," Piferoen notes. "Who knows if that food is really being kept above 140 degrees? And what happens if someone forgets to put the Sternos in?"

Banquet facilities should look more into combi-ovens for their holding ability alone. You can save a lot in energy and labor costs. Piferoen sees a day in the not-too-distant future when combi-ovens will be preprogrammed by the executive chef before he heads out to remote catering jobs, ensuring consistently cooked foods.

Coughenhour takes a slightly different path to the retherm process: he preplates seasoned cooked vegetable and side dishes and holds them in the walk-in until needed. Come service time, Coughenhour warms the plates in his combi-oven, cooks the protein to order, and finishes up the plate. "We can handle about 60 plates," Coughenhour says, "which works fine for us. But you can add more racks if you need them. I've definitely seen lower labor costs on the banquet side." He also points to another significant advantage: with combination cooking, there is no transfer of flavors between different foods in the cabinet.

But, as Mayonove comments, "Just because you've shelled out a lot of money for equipment doesn't guarantee you good food. You still need good cooks and training." Just as in the old days.