Steamers & Combi Ovens

By Staff -- Foodservice Equipment & Supplies, 9/1/2006

Types: The three major models of steamers are pressure, pressureless (convection) and connectionless. The first utilizes from 5 to 15 lbs. of pressure per square inch (PSI) and cooks at 228°F. to 250°F. Pressureless steamers cook at 0 PSI and 212°F. Heat is transferred via the convection of steam. Unlike pressure cookers, pressureless steamers put steam in direct contact with food products. Connectionless units are most often used by small- and medium-sized operations that lack water utilities or drains.

Capacities/Footprints: Combi ovens save kitchen space by combining the functions of two or more pieces of equipment into one. Countertop and small floor-model steamers work well in lower-volume foodservice facilities. Large floor model units are designed for high volume operations. As for the number of compartments needed, the rule of thumb is this: 0 to 200 meals per hour require a single 1-compartment steamer. For 200 to 400 meals per hour, a single 2-compartment unit will be required. Operations producing from 400 to 600 meals per hour will need one 3-compartment unit. And, to prepare 600 to 800 meals per hour, operators need either one 4-compartment or two 2-compartment units.

Energy Source(s): Combi ovens that run on electricity require 3.9 kw for smaller, countertop units and as much as 75 kw for larger models. Gas units, all floor models, range in Btu requirements from 45,500 to more than 170,000.

Standard Features: Some combi models offer options to control both cooking temperatures and humidity levels. The majority of combi oven models, however, come equipped with a trio of standard settings. One is fan-forced, pressureless steam for vegetable dishes, seafood and other delicate items. Since it will not dry products out, the fan-forced pressureless steam setting works well when reheating prepared foods. The second basic setting is combination mode. This blends steam with forced-air convection, providing moist heat for baking crusty rolls and breads, and roasting meats. The third setting is straight convection, which dry-cooks such menu items as pizza, cookies and cakes. Some double-stack units provide energy and water savings by operating only one steam generator at a time.

New Features/Technology/Options: One combi oven automatically maintains consistent humidity levels. Another combi oven line has an option that provides memory for up to 250 cooking cycles. A computer software option also is available with some combi ovens that provides HACCP documentation. Load-compensating thermostats automatically adjust cooking time by the volume of food cooked.

Prime Functions: A combi oven combines three cooking modes: steam, hot air and combi cooking, which melds hot air with superheated steam. The moisture maintains flavor and nutrients in food products, while the hot air speeds cooking up to 40 percent faster than conventional convection ovens. Combi ovens can also replace holding units, proofers or slow cookers when used at low-heat settings.

Key Equipment Applications: Combi ovens can quickly and efficiently prepare food items, ranging from roasted meats and vegetables to puff pastries. They also thaw and blanch.

Purchasing Guidelines: Much of the appeal of combi ovens is that they can cook three different ways, therefore, lowering the overall cost of an equipment package.

Maintenance Requirements: Water deposits and/or scale build up constantly on steam generator walls, heating elements and water probes. A stainless-steel liner in a convection steamer’s cooking compartment prevents rusting. Other helpful features include a coved corner liner for easy cleaning and heavy-duty commercial plumbing components. An auto steam generator blowdown can also reduce mineral buildup.

Food Safety & Sanitation Essentials: Steamers’ stainless-steel walls are generally easy to clean. Unit staff should start by applying a degreasing spray and follow by running the equipment on steam mode to loosen stuck-on particles. Staffers should open the machine’s doors during cooling, and scrub it only with soft brushes. They should also use a clean, dry cloth to wipe down the exterior. An easy-access, front-mounted deliming port allows operators to reduce scale and buildup without tools or costly service calls. A recent steamer line features open free-vented drains in the cooking compartment that allow food waste and condensate to drain out. This eliminates foaming and avoids contamination of the water reservoir, increasing food safety. Open-style water reservoirs are easier to inspect and clean, and don’t need deliming since they are not immersed in water.