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Warming / Holding Cabinets and Heaters

A food service Warming Cabinet (aka. Holding Cabinet) keeps food warm, fresh and safe until people are ready to eat. At the heart of food holding are the heaters and control systems that provide reliable, repeatable and safe results. Food holding equipment finds usefulness throughout the prep-to-delivery process. From the back of the house to the front, hidden or displayed, food holding is the secret ingredient that expands kitchen capability and decreases waste.

Food industry professionals today are looking for finer temperature and moisture control in their holding equipment. They also want longer hold times while maintaining food quality. A fast food restaurant that can hold fries another ten minutes without drying will have substantially less food waste during slower periods. The restaurant is looking to dial in that profile for the particular food being held. Finer control means better safer food held longer. The goal is to design the unit to regulate the environment faster with more precision. Materials and insulation play an important role but the critical component is the heating system.

The following are heaters used in various types of food holding equipment.

Tutco-Farnam has decades of heater design and control experience. We manufacture air and surface heaters that improve product performance and reduce cost. Whether you are looking to improve hold time or fine-tune temperature and moisture control, Tutco-Farnam can work with you to configure a standard product or design something completely custom. Contact a knowledgeable sales representative today with your unique heating needs.

Holding Cabinet Benefits

There are two primary food holding cabinet benefits. They are ‘food safety’ and ‘operation efficiency’.

Food Safety

Food held at an unsafe temperature for too long will expedite the growth of pathogens. Bacteria and viruses can grow in foods within 2 hours and even faster in hot weather. The CDC identifies ‘Inadequate Holding Temperatures’ as one of the 5 risk factors responsible for foodborne illness. Of the three basic principles of food safety one is dedicated to Time & Temperature Control. The other two are Hygiene and Cross-contamination. Approximately 3,000 people a year die in the US from foodborne illness. The National Restaurant Association has said the average cost to an restaurant for a foodborne illness incident is estimated at $75,000.

Temperature Danger Zone

The range of unsafe temperatures is known as the Temperature Danger Zone and it ranges from 41ºF to 135ºF with the most rapid pathogen growth occurring between 70ºF and 125ºF. Over the course of hours one bacterium can grow to thousands. The FDA Food Code recommends no more than a cumulative 4 hours in the danger zone. Exceptions include things like dry crackers where pathogens can live but are not likely to reproduce.

Warming cabinets hold food at ~140-141ºF unless a special process is required such as the proofing of dough for bread and pastries. With the aid of a warming cabinet, time and temperature are highly controllable. A quality heat source and control mechanism are key to reliable safe results.

Efficient Production

A chef who can prepare food in advance is able to serve more delicious food during big meal rushes. If you’re expecting a big rush between 11am and 2pm, there are tremendous savings involved if you can do a bunch of up-front prep and hold the food without losing quality. You save on food waste, you save on production efficiency and you make money serving a greater number of hungry people. Temperature controlled cabinets provide production flexibility. The line cooks for a 300 guest catered event will find it difficult to pump out that much food all at once and efficiently get it on tables. The holding cabinets give the production team an early start. When that initial food is prepared the cabinets free up the ovens and stoves allowing for additional food production. Mobile cabinets are great for wheeling previously prepared food to a more convenient location freeing up space and making the final food delivery faster. All of this is done to help with speed of service, handling ease, serving temperature and safety.

Standard Cabinets, Variations and Combos

Your standard full size cabinet is 1200 to 1500 watts. The type of heat supplied is either convected air or radiant. The heating element is at the top or bottom and may include a fan or crossflow blower to move the air around. Ducting channels may be used to deliver hot air more precisely achieving greater temperature uniformity. Moisture from heated water will also introduce heat into the cabinet environment.

There are different types of Holding Cabinets each with it’s own set of features and benefits. Many of them are 2-in-1 appliance combos based on your typical holding cabinet and some other feature that extends a units usefulness.

Cook and Hold

A Cook and Hold Cabinet allows you to prep the day before and let the food cook and hold overnight. In most units you can stick in a probe to measure a precise internal temperature that automatically switches the unit from a cooking temperature over to a hold temperature. This is a very important piece of equipment for many kitchens. Some operations serve right out of the appliance and only turn it off to clean it.

Heated Banquet

Heated Banquet Cabinets have heavy duty construction including sturdy casters and large handles that make the units more maneuverable. Capacity is often measured in number of covered plates it can hold. 96, 128, 144, 180, 192 and 200 are common plate capacities. Banquet Cabinets use electric heaters though some models will have a canned fuel heating option so you can unplug and reposition away from electric power. Features offered include white boards and clipboards for instructions and labeling.

Institutional Holding

Institutional models are robust and often customizable. This is heavy duty equipment designed for large operations like school cafeterias, convention centers, large banquet halls, catering services and hospitals.

Correctional Holding

Specially designed to be durable and not come apart easily. Anything that would normally be screwed in place is either welded or has some sort of non-traditional tamper-proof safety hardware that is difficult to remove without specialized tools. Electrical components and controls have additional coverings to make them more difficult to access. One or more door locking mechanisms are common. Some units are designed to hold correctional trays. Additional heavy duty transportation hardware may be added to secure doors on units that routinely transport food from a remote location.

Pizza Holding

Pizzas are held at low humidity between 160-180ºF. If they are in a pizza box then they are held at zero humidity at ~180ºF. Pass thru cabinets are popular options that help with production flow from production line to checkout counter. Higher capacity models for kitchens are built to accommodate boxes, bags and/or pans depending upon the model. Smaller versions can be found in the kitchen as well as counter-top models. Pizza cabinets large and small are often decorated with promotional vinyl marketing wraps.

Holding and Display

Cabinets meant for hold and display are referred to as Display Cases and in some instances may be referred to as Merchandising Cabinets. They will have windows on 3 or more sides for viewing. Some units use a rotating carousel of pizza trays, which helps to maintain even temperatures throughout the product.

Modular Holding

These are smaller stackable holding units with one or more food holding bins or pans. They commonly sit on a counter or shelf holding cooked food prior to final assembly. You may have witnessed a food assembler at your local coffeeshop chain pulling sausage and egg patties from one of these units prior to making your breakfast sandwich. The food bins may have a single entry or may have a pass-thru design. Warm air may blow from the side by way of a crossflow blower, by radiating heat from a foil or flexible surface heater or by a completely custom approach.

Roll-In Racks

Roll-in oven racks are designed to fit into specially designed ovens and holding cabinets. Roll the food into the oven and then when it is done roll the food out of the oven and into a holding cabinet. Special casters that can handle the heat are used. Roll-in racks made to hold dinner plates with lids can be loaded up with food and wheeled into the holding cabinet until serving time.

Hot Food Transport

Units built specifically for transport are used for mobile catering and for delivering to an institution that uses a remote kitchen facility. Think durability, big castors, doors that latch, recessed handles, bumpers and secure tray fittings. Some units have a battery to keep a fan circulating warm air while in transit.

Proofing Cabinet

A Proofing cabinet (also called a Proofing Box) are specifically designed  for bread and pastries. They heat and hold at lower temperatures from approximately 75-120ºF. Humidity control will be somewhere between 70-90%.

The dough rises more evenly in this warm humid environment before baking. Humidity can come from a manually inserted water pan or by connecting the unit to a water source that allows misting/spraying moisture onto a hot surface like a metal plate. Some owners add a water filter.

Proofers are thermally insulated and typically have blown air to help establish environmental uniformity. Automatically reversing airflow direction from time to time can provide greater evenness throughout the process.

Holding Proofer Combo

These combo cabinets give you more versatility with the same piece of equipment and saves space in the kitchen. The heating system and components in these units are designed to satisfy a greater range of temperature control. The dough goes in for the proofing. Then it comes out and goes into the oven. Then back in the same unit for holding.

Retarder Proofer Combo

This is another time and labor saving combination unit but in this case we’re combining cold storage with heated storage in a humidity controlled environment. Fermented foods can be ‘retarded’, which means the yeast activity is slowed. This allows the dough to be stored for a period of time. The retarder also offers precision control of the leavening process.

A retarder proofer appliance can be set up to run overnight or over the course of several days. The retarder aspect of the cabinet allows the dough to be refrigerated but rest at a slightly higher temperature than a typical refrigerator. For some types of dough this slightly higher temperature is preferable. Sourdough recipes often benefit from a retarding process.

Airflow will be minimal during the initial cold storage stage but will pick up during proofing. The operator sets a timer to tell the unit when proofing should start. The product will be oven-ready based on the operator setting. Retarders can also be used to thaw frozen dough.

Oven Proofer Combo

Proofing happens at a lower temperature (~120ºF) while baking will be a lot higher (350ºF - 450ºF). Baking temperatures are determined by two main events that happen during the baking process, the expansion of gas cells and the coagulation of gluten and gelatinization of starch. The temperature will depend upon the ingredients used and the ‘richness’ of the dough. Lean dough bakes at higher temperatures.

Retarder Proofer Oven Combo

The ultimate all-in-one. The temperatures range will be something close to 50-600ºF.

Other Cabinets

Food holding may exist in other forms including chip warmers, draw warmers and merchandising cabinets. Serving wells can have warming cabinets tucked underneith them. Meal delivery or room service carts may contain or actually be a mobile warming cabinet.

Warming cabinets are most commonly used in food service but they also find their place in other industries. In a healthcare setting we’re primarily warming fluids and solutions or blankets and towels. These units are typically sold by companies that sell exclusively to the healthcare industry. Warming cabinets are used in hospitals, family practice, physical therapy, massage, salons and spas.

Considerations Before Buying

Vendors

You can buy new, used, rent or lease. There are two types of vendors in the new equipment arena. You can buy from a single source supplier that can provide everything that makes heat in a kitchen. All of the equipment can be from a single brand. You can also buy from a specialty supplier that focuses on one type of equipment. There are companies that design, manufacture and sell only French Fry warmers, for example.

Dimensions

A holding cabinet needs to physically fit among your other equipment as well as the work space reserved for the cooking and wait staff. Cabinet doors need room to open and can usually be hinged from either side. If it is a mobile cabinet it will need to fit through doorways with casters large enough to handle any bumps along the way. Consider height of doorways as well as any protruding door handles. Some shorter models are stackable. Vertical real estate is usually cheaper. Under counter space can be filled with an undercounter cabinet. Planning out your kitchen and serving spaces to scale on graph paper can be a useful exercise.

Energy Use and Efficiency

Keeping food safe and warm involves many variables including the design of the unit, control settings, surrounding environment, and the way in which people interact with it. Insulating materials can be high density solid core foam, standard fiberglass or even no insulation on cheaper models. A stainless steel body will insulate better than aluminum. Self closing doors and quality gaskets help to keep the heat in. Ambient air brought into the unit as part of a moisture control system will have an affect. Other variables include the ambient temperature outside, heating control methods, temperature uniformity and the frequency of door openings will all make a difference in how hard the system will need to run. Some units are specifically designed to be Low Wattage units. According to EnergyStar.gov, hot food holding cabinets that have earned the ENERGY STAR are 70% more energy efficient than standard models saving on average $300 per year for electricity.

Mobility

If a cabinet needs to be moved it needs to be durable. The more you move it the more durable it should be. Some vendors claim dent and impact resistant body materials on their more durable cabinets. If you are moving cabinets from the back of the house to the front or perhaps moving food around a hospital moderate durability should suffice. If it is going to be loaded on trucks for multi-location catering or daily institutional delivery then you are going to want a design intended for that purpose with sturdy welded construction, good bumpers, stout maneuverability handles and large locking casters. Alternate power options like canned fuel and batteries are useful when outlets are not available. Special weather protections are available for some units.

Food Containment

Several different common types of food containment are available to you and they will be dictated by the food you need to hold. Food is going to be held in pans, trays, baskets, sheets or covered plates. Those food containers will be suspended within a cabinet by shelves, slides, bins or wire loops specifically designed for holding round covered plates. Shelves can be solid or have holes in them. Slide options include fixed wire, lip load, bottom load and universal. Some considerations for internal arrangement include versatility, stability and ease of cleaning. If the interior is versatile you can hold many different types of containment devices and adjust your slides or shelves accordingly. Stability is particularly desired for transportation and correctional holding. Cleaning is a regular task. If you can place a hand below a rung and move upward catching 5 or 6 rungs in a single movement, that's a quick way to move complicated geometries to the dishwasher.

The Future of Food Warming

In the early days of food holding the goal was to keep food safe. Restaurantures started realizing the fantastic capabilities and savings inherent in food holding and that has pushed OEMs to develop equipment with longer hold times. Entire kitchen processes have developed around food holding and now food service professionals want to push the boundaries further. This is happening simultaniously as customers are demanding more quality in their food. As a result, the food service industry is pushing for equipment redesigns so that kitchens, caterers and institutions can hold their cooked food longer and without sacrificing quality. Food holding cabinets are at the heart of this endeavor and finer thermal control is the key.

This new breed of super equipment is being developed right now. It's coming from the minds of engineers who are rethinking the heat source, the moisture component, the control system, heat delivery and the overall redesign of traditional kitchen equipment. At Tutco-Farnam, heaters and temperature control is our specialty. We have worked with numerous equipment manufacturers to develop uniform, efficient and tightly controlled heating systems that safely hold food longer without sacraficing food flavor and integrity. We can supply standard models or design something completely custom. Contact us today with your unique appliance heating needs and see what Tutco-Fanam can do for you.

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