Steamers are used primarily to cook vegetables, seafood, and other foods where moisture retention is essential to visual appearance and taste. Food cooked in a steamer also maintains more of its nutritional value.
Steam cooks food much faster than hot air and reduces shrinkage, improving productivity and increasing profits for the food service establishment. Steam equipment is relatively easy to use, even for the inexperienced food service operator. Many models include programmable controls that take the guess work out of the cooking process.
Steam also preserves the nutritional value of most food. This is becoming more important to today's health-conscious consumers. The convection steamer can cook a variety of foods at the same time with no transfer of taste from one food to the next. This improves food quality and consistency as well as productivity.
Combination oven/steamers are becoming popular as well. By combining the dry heat of a convection oven with the moist heat of a steamer, chefs can choose among three different cooking modes making this piece of equipment extremely flexible and productive.
Steamers look and operate much like ovens. An electric or gas boiler generates the steam and injects this steam into the cooking compartment. Steam is a much quicker heat transfer medium than hot air. For example, a full size turkey may take hours to cook in a conventional hot air oven, but will cook in minutes in a steamer.
In addition, steam energy is transferred at lower temperatures thereby reducing the chance of overcooking the food product. For example, steamers operate at temperatures of 212° to 240°F, while a typical hot-air oven operates between 350° and 450°F.
However, cooking at this lower temperature does not brown food as effectively as a hot-air oven. This is why chefs will often use the steamer to cook food almost to completion, and then transfer that food to a conventional oven for a short period of time for surface browning. They may also use a combination steam/hot air oven designed to do both.
Steamer cooking performance depends on food product cooking time and the steaming capability of the steam generator. Cooking food for the proper amount of time within the capabilities of the steam generator results in consistent quality, portion after portion.
Many new steamers have programmable controls to maintain consistent cooking time and steam volume inside the unit. Food service operators need only set the amount of time each dish must cook to properly operate the steamer. These programmable controls also permit the chef to pre-program cooking times so less experienced employees need only choose the food item from a menu located on the control panel.
Electric vs. Gas
There are many factors to consider when selecting a steamer: first cost, food preparation productivity, ease of operation and heat generation in the kitchen, as well as the energy source used, electricity or gas. Keep in mind, energy only accounts for 3 to 5 percent of a food service establishment?s total costs. So, while one fuel may be less expensive in a BTU to BTU comparison, the best choice in cooking equipment is the one that minimizes total operating costs, not just energy costs. Features that reduce labor costs or result in higher food product yield will nearly always outweigh any energy considerations. Make sure that you include all of these factors in any equipment evaluation.
Let's take a closer look at the energy use issues, remembering that comparisons should be made on the basis of similar equipment where only the energy input is being changed. Electric steamers generally offer these benefits:
- Electric units are more efficient so they add less heat to the kitchen, which ultimately must be removed by the cooling system.
- Electric units require less maintenance, require less ventilation, and are more portable.
- On the other hand, the primary benefits of gas and propane are that they are often a less expensive energy source than electricity.
- Pressureless Steamer
The pressureless steamer uses steam at atmospheric pressure to cook food at a constant temperature of about 212°F(near sea level). This temperature is a function of altitude so pressureless steamers operating at high altitudes would have different cooking times due to the lower steam temperature.
The boiler injects steam through the sides of the cooking compartment where it contacts the food, releasing heat energy as it condenses. This unit can cook a variety of foods at the same time with no transfer of taste from one food to the next. The chef can open and close the door at anytime to stir food or check on the cooking progress. These units are usually equipped with programmable controls and are available in countertop or floor models. Some models are stackable to help reduce kitchen floor space used.
- Convection Steamer
The convection steamer operates much like a conventional pressureless steamer. It offers slightly more uniform temperature distribution throughout the cooking compartment by employing a fan to circulate the steam and air mixture. This is similar to the way convection ovens circulate hot air. The convective flow of steam accelerates heat transfer to the food.
- Pressure Steamer
The pressure steamer uses steam supplied at 5 to 15 pounds per square inch, or "psi". It is very similar to the old pressure cookers you may have grown up with as a child. You may remember it had the advantage of cooking meats and stews much quicker. They also tenderized tough grades of meat.
Pressure steamers have a door that locks down to seal in the steam and hold the higher pressure and associated higher condensing temperature in the cooking compartment.
These steamers have always been popular in large kitchens, schools and institutions.
The disadvantage of a pressure steamer is that the chef can't easily access its contents. The unit must be depressurized before opening, and once it's closed again it takes a while to regain its operating pressure.
- Combination Oven/Steamers
Combination units merge the advantages of the moist cooking of steamers with those of dry air cooking in a conventional oven. These units are often praised for their versatility. Chefs can use the oven mode to help with baking and roasting during peak traffic times or use the steam mode when extra capacity is required. However, the most important quality of a combination unit is its ability to cook in the combination mode.
The combination mode is controlled by a microprocessor, which alternates between steam mode and oven mode for various types of foods. For example, under the steam mode, roast beef will cook in about half the time it takes in the oven mode. However, customers prefer to see the meat "browned." The combination unit can cook under steam until the meat is mostly cooked, then automatically switch to oven mode to finish cooking and produce the browned effect.
- Vacuum - Steam 'n' Hold
The steam 'n' hold cooks food to the exact temperature, then will hold it hot until you are ready to serve. By setting the temperature (range is between 160°F and 212°F), the food can be cooked with variable temperature steam created in the steam 'n' hold. Once the food reaches that desired temperature setting, the food automatically holds at that temperature since there is no more temperature for the food to absorb.
The interesting feature of this steamer is it cooks at below atmospheric pressure. It actually pulls a vacuum; therefore, lowering the boiling temperature of water.
Some of the features of the Steam 'n' Hold include:
- No boiler
- Cooks and holds food hot for hours
- No maintenance required
- Lower equipment cost
- No water hook-up needed
- No drain hook-up needed
- No water treatment necessary
- Eliminated over cooking
- Easy and safe to operate
- Uses 1/10th the energy of existing steamers
All steamers have a cooking compartment that looks a lot like the inside of an oven. Some units actually have more than one compartment. Each compartment will hold about 3 full size steam pans, but sizes vary according to manufacturer. The cooking compartment is usually made of stainless steel making it easy to clean and resistant to corrosion. A drain located in the bottom of the cooking compartment drains off excess water that condenses inside the unit.
Pressureless steamers have a door that simply latches in place. These units may be opened and closed during the cooking cycle. Pressure steamers are equipped with a door that locks tightly to hold pressure and prevent steam leakage. These units generally should not be opened during the cooking cycle because they would emit a burst of steam through the oven door, much like the first burst of steam from a boiling pot of water. This is hazardous to kitchen workers for obvious reasons.
Steam can be provided from a boiler built into the unit or from an outside source. Built-in boilers use gas or electric energy to heat water similar to any other boiler unit. Steam flows into the cooking compartment through small holes or jets usually located on one side of the cooking compartment.
Many units also use a set of condenser coils located opposite the steam jets to capture excess steam. They condense the steam back into liquid water and drain it out the bottom of the unit. This prevents tastes from transferring between foods.
The convection steamer has a fan inside the cooking compartment which circulates the steam/air mixture, increasing air movement and heat transfer to the food. This results in the convection steamer cooking food slightly faster than a conventional unit.
Steam equipment incorporates relatively simple technology. Most of the improvements have come in the way of microprocessor controls. These newer electronic controls take a lot of the guesswork out of steamer use by pre-programming cooking times for specific food products. Other models are available at lower steam pressures called vacuum units. They can cook foods at temperatures below 212°F.
Steamers are relatively quick ovens to preheat because of the high heat transfer characteristics of steam. They are also usually well insulated by the manufacturers to reduce heat loss to the kitchen. Therefore, they require less energy to stay up to temperature during slow times. However, if you are using more than one steamer during peak times, turn one unit off after the peak cooking cycle. Also, try to keep the unit fully loaded when possible. The steamer operates at peak efficiency and productivity at full load.
One key ingredient to steamer operation is controlling water quality to the steamer. If the water in your area is "hard" or contains chemicals in any significant levels, these can coat and corrode the steaming components. This scale and possible chemical carryover can deteriorate steamer performance, food quality, and almost always results in premature steamer component failures. Always check with a professional water treatment company about proper water softening for this equipment.
Keep the unit properly maintained. Check to see that the door seals properly so that steam doesn't escape into the kitchen. Make sure that the boiler is clean, burners or heating elements function properly and steam injectors are free of any debris. Remember, a clean and well maintained unit operates more efficiently and will reduce repair costs.