With keeping food warm a major concern of all types of foodservice operations, manufacturers have provided a wide range of equipment. Food-warming options fall into four major groups: radiant warmers, “pot” warmers, cabinet warmers, and hot-food tables. Each has a number of types of equipment. For example, the basic principle of the radiant food warmer is that a heat source radiates heat toward food, heating it without heating the surrounding air. There are several ways to accomplish this.
“Pot” or liquid food warmers work about the same way but vary widely in appearance. That appearance is often designed to merchandise the contents. Although cabinet warmers are also often used for merchandising, other types are used in the back of the house and for transporting food from kitchen to point of serving.
Two Classes of Hot-food Warmer
Hot-food warmers are divided into two classes. One keeps food hot with moist heat, such as steam tables or bains maries. The other uses dry heat. Both accomplish the desired result, keeping food at serving temperatures over an extended period. The heating source that does the job varies, too. Although electricity is the predominant source, some models use gas and some use jellied fuel. With gas, some units require connection to a gas line while some portable styles use propane tanks.
Because warmed air is drying, most manufacturers supply warmers that permit adding moisture for higher humidity. A typical humidity system involves a water cup with a heating element. More sophisticated units have a humidity control, like a heat control, that allows the relative humidity to be set for different foods. A sensor is placed in the cabinet to monitor humidity. When the humidity falls below the selected level, the heating element in the water container is switched on.
Although some operators use cook-and-hold ovens as warmers, this greatly ties up a versatile piece of equipment. Many cook-and-hold ovens do not have provisions for controlling humidity for long-term holding.
Radiant heaters are found just about everywhere. Common spots are over food passthroughs and buffet-table carving stations. They are also used over french-fry pans and hamburger racks in fast food, plating stations in restaurants, and cafeteria lines. Radiant heat is emitted in the infrared portion of the light spectrum. It’s normally invisible, although some sources emit a small amount of light, usually a reddish glow. Infrared warmers heat surrounding air very little.
Radiant-warmer design may be as a lamp, strip, slot, or tunnel. Some are mounted in place, others are portable. A radiant warmer may use anything from an ordinary incandescent light bulb to a high-tech infrared radiation tube or strip. Since incandescent bulbs emit a lot of heat, they are little used.
Infrared may be generated by a special bulb. It also may come from a resistance wire which glows red, a special tube, or strips of resistance materials such as quartz, ceramics, or plate emitters that give off no visible light. Most warmers are designed to prevent accidental contact with the hot element or bulb. As a result, reflectors usually project far below the lamp or heat-source surface. Placing a hand under the warmer will not cause burns or even irritation, although prolonged exposure may be uncomfortable. Even at a carving station, where hands are continually under the heat source, no burns have been reported. There is also no danger in looking directly at the heating element.
Radiant warmers will not cook food, and they do not put out enough heat to warm food from room temperature to serving temperature. They are intended to retain food heat without additional cooking and minimal drying.
This type of warmer, intended to keep liquid foods warm, is used for things like soup, chili, sauces, and stews. Pot warmers, which are used by both staff and in self-service, can play a merchandising role. Portable units are often shaped like cast-iron pots or stone crocks, intended to give a homemade, appetizing appeal to the food they contain. Other pot warmers are designed to be built-in countertops. Typical applications are in soup and salad bars, coffee-shop back bars, and built into serving lines that do not have steam tables.
Pot warmers are almost all electrically heated. They hold their contents in a stainless-steel pot or steam-table inset that fits snugly into the “well” in the warmer. Warming is performed by electric coils around the outside of the well. Some pot warmers are so well sealed that they may be totally immersed in water during washing. Others must be cleaned with a damp cloth or sponge to keep controls and elements from getting wet. Because the food is held in an inset, minimal cleaning is needed.