Combining convection oven and steamer capabilities into a single cooking cavity has been one of the great foodservice innovations of the past quarter century. Other great cooking equipment innovations like the microwave oven and induction burner have also changed restaurant kitchens, but no other piece of equipment can match the combi oven's productivity and ability to do so many types of products so well. When you ask many chefs to name the most versatile pieces of equipment in their kitchen, the combination oven/steamer is invariably at or near the top of most lists. Today the combi's popularity has grown so much that they are common in many types of operations. However, if you don't have one yet, here are some aspects of their use to consider.
The combi oven combines three modes of cooking in one oven — steam, circulated hot air, or a combination of both. The combination mode is used to re-heat foods and to roast or bake. The steam mode is well suited for rapid cooking of vegetables and shellfish. The hot air mode operates as a regular convection oven for baking cookies, cakes and pastries. The combi mode decreases overall cook times, reduces product shrinkage and eliminates flavor transfer when multiple items are cooked simultaneously.
Some models offer additional specialty modes using hot air and steam to defrost, rethermalize, poach or gentle steam, and warm. Many types of red meats and poultry products are well adapted to combination cooking because they can be prepared so many ways. Steaming of vegetables and fish, of course, is easily done. The steamer/oven operating in the combination mode, mixing forced air convection for even browning along with steam for moist heat to reduce product drying that is wonderful for many types of foods. The combination mode is especially well suited for producing less shrinkage in meats than typical ovens. Breads and rolls baked in the combi mode will be fluffier and have more oven spring than those baked in traditional ovens. Rethermalizing leftovers and heating prepackaged frozen convenience foods also works well in the combi mode to reduce drying and over browning.
There are still other reasons to use the equipment. From a kitchen layout and space point of view, the really great thing about a combi is that it can replace two pieces of equipment in the space of one. Space is the ultimate premium in many operations these days and today's kitchens are shrinking because we can't afford the luxury of space found in many older kitchens. The combi takes up about half the area of a convection oven and steamer that may free up space for other equipment or just some badly needed work space.
The space saved can translate into cost savings as well. By eliminating one stainless steel exhaust hood and reducing the amount of exhausted conditioned air over only three or four feet can result in significant first cost and operating cost savings. The hood cost along with the savings due to reducing or consolidating pieces of equipment can be significant but the typical combi is still expensive. However, if you are planning to buy a combi oven in place of two or more pieces of equipment, be sure that the menu and operation will not require the unit to handle different functions simultaneously. While a combi oven can do the job of both a steamer and an oven, it can't do both at the same time!
There is a relatively new type of combi that promises to make owners happier about the cost of these units. Several manufacturers have engineered lower-cost, boilerless lines The expensive boiler is eliminated and the resulting steamer/ovens cost about 15-20% less than the typically sized counterpart. The only drawback is slightly reduced steam output, although that is sometimes needed in high volume fast cooking. In many applications the difference is not critical. These new boilerless units have opened up an additional market for combi ovens and made them suitable for even more operations. There is an added benefit to the boilerless combi — reduced liming problems due to hard water. Over half of combi maintenance problems are due to excessive scale and lime build up, and this can be minimized in a boilerless model.
The oven/steamers on today's market range from small volume countertop units to floor-mounted roll-in units with large capacities for banquets or institutional use. Typical sizes are stated by manufacturers in standard steamtable pan (12"×20") or baking sheet pan (18"×26") capacities. Note that shallow 2 ½" pans are typically used in the sizing ratings. You will need to reduce capacity accordingly if using 4" or 6" pans that would be most typical for casserole items or lasagna. Most manufacturers make several of the more popular oven sizes used in restaurants. The models most available are the four to six 12" × 20" pan capacity countertop unit, a seven to ten pan unit and the larger floor or stand mounted 14, 18, and 20 pan models. The smaller units generally hold only a 12"×20" pan or half size baking pan. The larger units hold two 12"×20" pans on each shelf or a single 18"×26" baking pan.
Once the necessary size unit for your operation is determined, a primary consideration is whether the combi will be electric or gas-fired. All sizes and styles are generally available as electric units. Gas units are produced by fewer manufacturers and in fewer sizes and are usually more expensive than electric models. If you are considering an electric unit, be sure to have enough power as they generally entail a fairly substantial load. For example, a ten steamtable pan size unit requires between 13 and 19 kilowatts to operate.
When selecting equipment, you also need to be aware of and perhaps choose among numerous options. Evaluate your needs carefully, as every step up in features will generally thousands of dollars even in a small counter-top model.
Most units are fully stainless steel inside and out with a glass window. They are generally easy to clean although several models have a built in spray hose for washing out the interior that helps in the cleaning process. Speaking of cleaning, also take special care to maintain these sophisticated pieces of equipment. As with all equipment that uses water — from steamers to ice machines — the water that is fed into a combi should be treated with a filter system. Filters will slow mineral deposit build-up in the unit's water lines and water contact areas and reduce the buildup of scale on a combi's heating units, water probes and cooking chamber.
There are some subtle advancements in combis being made by several of the main manufacturers. One improvement is in enhanced fan design for more even air movement. Another is better self cleaning options for those who want to pay for this labor saving feature. One manufacturer has added a microwave cooking option in a special model that features the three standard combi modes plus an additional mode using a microwave-assisted cycle.
Most any operation can take advantage of the combi-oven's versatility and benefit from the wide range of food products that can be cooked in the units yielding high quality results. Wide acceptance and appeal among chefs and clear advantages in food preparation have made the combi oven an expected item in the modern professional kitchen. And once you have a combi-oven in your cooking lineup, you will never want to be without one again.
Dan Bendall is a principal of FoodStrategy, a Maryland-based consulting firm specializing in planning foodservice facilities. He is also a member of Foodservice Consultants Society International. Bendall can be reached at 301-926-8181.