Having the right tools for the job makes all the difference. In a commercial kitchen, food rethermalizers and food warmers are two important tools. You might think these appliances do the same thing. However, their function is very different. Each has unique benefits.
What is a Rethermalizer?
In general, rethermalizers are appliances designed specifically to reheat prepared foods from a chilled or frozen state of less than 40°F to a temperature of more than 165°F safely and quickly. They don’t require food to be slacked or thawed before retherming. Rethermalizers must be capable of boosting food temperature through the “Danger Zone” (between 40°F and 140°F) in under two hours (not to be confused with Kenny Loggin’s classic Danger Zone). This is critical because bacteria reproduction goes into overdrive within that temperature range, doubling every 20 minutes. Once food passes 140°F those little bacterial bastards are killed off.
Most rethermalizers use water as a heat transfer medium.
Uses for a Rethermalizer
Just as the name implies, rethermalizers reheat food. They are especially useful in operations that prepare and freeze large batches of food ahead of time. Ideal menu items for retherming include soups, casseroles, sauces, pasta, vegetables, bread, desserts, and meats.
We all know that finding good help right now is a royal pain in the butt. With no end in sight to the tight labor market, it’s important to have tools that are easy to use and don’t need a lot of babysitting. Rethermalizers are a great option. They’re push-button simple, and most feature an automatic hold function. Many have programmed cooking functions, so staff can just load them up and push start.
Types of Rethermalizers
There are four basic types of rethermalizers: water bath, induction, combi oven, and CVap® Retherm Ovens. The first two are typically countertop appliances (though some large floor models are found in QSR chains). The latter two are usually floor models.
Bain Marie or water-filled rethermalizers use a water well to reheat food quickly and gently. Although this type can be a more economic option, there are a couple of disadvantages. Water-filled rethermalizers need about 15 minutes to preheat before adding the product. And it’s necessary to check the water level about every two hours. Allowing the water level to drop too low can damage the unit and burn the food.
Some water bath rethermalizers are sous vide immersion circulators. Food is prepped and sealed in vacuum bags. It can be cooked right away, or chilled or frozen for later use. The bagged products are placed directly in the heated water bath. Once it reaches serving temp food can remain in the water bath until serving. The water bath prevents it from overcooking or cooling down.
Induction rethermalizers remain cool until an induction-ready inset is placed inside. They are very efficient since no energy is expended in preheating. Virtually all heat is inducted directly into the food, quickly retherming it. Because induction units don’t utilize water baths, they won’t develop the funky scaling that can develop in water bath appliances.
Combi ovens are popular for rethermalizing. Combis get their name from their combination of hot steam and hot convected air to quickly retherm food. They are hella fast, and hella powerful. But they’re also hella expensive and can be pretty damned complicated to use. Speaking of expensive, you’ll want to factor in the required chemicals and maintenance that combis must have.
Like CVap Retherm Ovens, combis don’t just thermalize. Most are capable of a wide range of other cooking processes.
CVap Retherm Ovens use heated water vapor as their primary heat source. This means you can retherm in a CVap oven with or without vacuum bags. It’s like sous vide, without the mess. CVap ovens can also roast, steam, bake, sous vide, low-temp steam, proof, and more. You can even use them as food warmers. They automatically shift from cooking to holding mode at the conclusion of their cooking cycle.
Rethermalizers vs. Food Warmers
Rethermalizers can be used as food warmers. But food warmers cannot be used as rethermalizers. They perform very different functions. Rethermalizers are designed to quickly heat food to safe temperatures. Although food warmer might sound like it does the same thing, that’s not the case. Food warmers are designed to keep hot cooked food at a safe temperature. They aren’t designed to heat up cold food. If anybody tells you different, they are either pulling your leg or are ignorant to the basic functions of kitchen equipment.
What is a Food Warmer?
Food warmers maintain food temperatures above the minimum safe temperature of 140°F. They are called several different things: warmers, holding cabinets, hot boxes, warming drawers, etc. Food warmers are great for operations that have predictable rush periods, like school cafeterias and fast-food restaurants. They allow cooking to be done ahead of the rush. Food is held hot until serving. This allows more efficient use of the staff on hand. Just like rethermalizers, many warmers rely on heated water in some form to provide continuous heat.
Uses of a Food Warmer
As the name implies, food warmers keep food warm. They are useful in rush traffic situations and in operations that need to serve throughout the day. Food warmers help provide quick service by minimizing prep time.
Types of Food Warmers
Food warmers come in all shapes and sizes. Some are simple, such as chafing dishes, heat lamps, warming shelves, and heated strips. The simpler warmers are only good for short-term holding, like on a serving line.
Countertop warmers are next up in the holding hierarchy. They include kettles, bins, and drawers. Kettles are great for soups and sauces. Bins usually hold full or fractional pans, so you can hold different products together (if they share similar settings). Warming drawers are great because they have a closed environment, enabling more precise control of food temperature. Drawers take up relatively little space, making them ideal for food trucks, concessions, and other operations where space is critical.
Finally, the largest food warmers are holding cabinets. These are available in under-counter, half, or full-sized configurations. They let you hold lots of food in a small footprint.
Just as there are different types of food warmers, there are also different technologies behind them.
Warmer Technologies
Dry warmers are just that. These drawers or cabinets, also known as “hot boxes,” use simple electrical heating elements to heat the unit interior. Because they don’t add moisture to the unit’s atmosphere, they can only hold for a short time before food quality starts to drop. Inevitably, food will start to lose its moisture. Not only does this dry the food out, but it also causes food temperature to drop (because evaporation is a cooling process).
Passive humidity warmers add a water bath to the unit’s interior. They are an improvement over dry warmers because the addition of a water bath means moisture isn’t being provided solely by the food itself. They are better than dry units but are less accurate than more sophisticated warmers.
Humidified warmers offer better temperature accuracy. Their internal water bath is temperature-controlled, which extends holding time.
The most accurate warmers are Winston’s CVap (controlled vapor) holding cabinets and warming drawers. CVap uses a dual-heat system of dry air heat and moist vapor heat. This means that CVap warmers precisely control food temperature and maintain the desired surface texture. CVap is equally effective at holding crisp or moist foods for extended times.
Rethermalizer vs. Warmer: Differences
As described previously, the biggest difference between rethermalizers and warmers is their function. Rethermalizers reheat or cook food. Food warmers do not. As mentioned before, you can hold food in a rethermalizer, but you cannot cook in a food warmer. Rethermalizers are designed for speed and require much more electrical power than warmers.
Rethermalizer vs Warmers: Similarities
Rethermalizers and warmers share some similarities. Many use some form of water or water vapor as the thermal medium to cook or hold food. Since water is efficient at heat transfer more energy is directed into the food than is wasted in the atmosphere.
Rethermalizer and warmers may have similar appearances. Although there may be some overlap in function, they serve different primary purposes.