Foodservice Equipment Reports

Prep Tables Change The Game

On the surface, some things never change, and that's a good thing. The basic principle of the FDA Model Food Code is "hot food hot, cold food cold," and while most operations focus heavily on how to keep hot, sometimes keeping cold deserves renewed attention.

Fortunately, refrigerated prep tables make cold holding easy, and today's unit styles and sizes are varied enough to suit virtually any operation. More importantly, just below the surface modern prep tables are sporting new cooling technology and efficient designs that can change the way you hold and prep.

To be clear, we're not talking here about a stainless worktable with an undercounter reach-in. Refrigerated prep tables do have undercounter refrigeration storage and countertop space for prepping or assembling products for cooking or serving. But they also have refrigerated wells to accommodate food pans, which allow employees easy access to a variety of ingredients.

Ideal for salad prep, sandwich making and pizza assembly, refrigerated prep tables can be used for a variety of other applications, too. You don't have to be a sandwich shop or pizza place to find good uses for them. In fact, you can find prep tables everywhere from schools, hospitals and B&I accounts to white tablecloth restaurants. Chains of all kinds are big users.

Sizing Up Styles
Prep tables come in a wide range of sizes, but you'll find just two basic styles when you go shopping—the raised-rail unit usually referred to as a pizza prep table, and the flat prep table, usually referred to as sandwich/salad prep unit. All have refrigerated storage space in the base.

Raised-rail prep tables have a refrigerated ingredient well stretching the length of the back of the table that's several inches higher than the workspace. This well, or rail, is typically angled toward the front of the table to make things more ergonomic. Tables generally are designed to hold three to 14 1/3-size hotel pans.

With just one refrigerated well, raised-rail tables provide anywhere from 15" to 20" of depth in the countertop workspace, usually covered with a removable poly cutting board. (There are a few models that have two-tiered wells, but since they're both positioned along the back length of the units, the same rule holds.) The workspace typically is big enough to prep extra-large pizzas, for example.

Sandwich/salad prep units are designed with a recessed well set flat into the top of the table. Standard units accommodate two rows of 1/6-size pans or a single row of 1/3-size pans. The smallest of these, a single-door unit, holds six pans. Workspace length typically ranges from about 8" to 13".

Most manufacturers also offer a line of "big" or "mega" top units that provide room for a third row of 1/6-size pans. These models typically are only 5" or 6" deeper than standard units but give you 50% more capacity. Obviously, you can use the extra capacity to put a greater variety of ingredients at employees' fingertips, or double up on volume so employees don't have to replenish ingredient pans as often. These units can accommodate from nine to 30 pans or more depending on size.

As with most other equipment, what size unit you need depends on your menu and volume. Manufacturers typically increase model sizes by the width of another reach-in door—24" in most cases, but you'll see units with door widths ranging from about 13" to 27".

Other factors, like floor space and operational considerations, also may come into play. Manufacturers developed the big-top versions of their flat cold prep tables to fit more capacity into essentially the same footprint as standard models. If you're tight on kitchen real estate, that could influence your decision.

On the other hand, if your volume warrants it, you might want to put that capacity into a longer standard model and create stations for two employees to crank out product.

Keeping Your Cool
The type of refrigeration used also differentiates one style of prep table from another (and even models of the same style). Cold prep tables are governed by NSF 7 standards that require the equipment to maintain uncovered food at temps between 33°F and 41°F in a kitchen with an ambient temp of 86°F.

In general, flat refrigerated prep tables use forced cold air to chill the pans in the well. Air is circulated below and between the pans. On many models, the pans are recessed below the level of the prep table's top, and ducts vent cold air over the surface of the food in the pans as well. This feature helps ensure the unit meets NSF standards, but can have the undesired effect of drying out food if it isn't used quickly.

Typically, raised-rail prep tables use mechanical refrigeration to chill pans in the well. Refrigerant lines run from the compressor around the well and through the pan dividers, encircling each pan well. This type of refrigeration provides more cooling power (metal conducts cold more easily than air) and faster recovery than forced-air systems.

However, depending on the environment, the refrigerant lines may freeze delicate and high-water content ingredients like lettuce and fluctuate in temperature when they go through defrost cycles. And a hot-gas defrost cycle could raise the temperature of food in the cold well into the danger zone, requiring your employees to take the pans out during defrost cycles.

A few manufacturers offer models that help address this problem. Some units are now available with sensors that monitor the temperature of the evaporator and run defrost cycles only when necessary instead of on a timed basis like most older systems.

There are exceptions, of course. Some raised-rail prep tables use forced air for cooling both the rail and the refrigerated storage area. And some flat prep tables use mechanical refrigeration wrapped around the pan wells to chill ingredients.

There's also a third type of refrigeration, used on some models of both raised- and flat prep tables. This design chills the food pans by running cold fluid through the divider rails. One manufacturer uses propylene glycol. So the unit passes refrigerant through one side of an evaporator plate and glycol through the other to transfer heat. The chilled glycol is pumped through the walls surrounding the food pans.

Another supplier uses a "eutectic" liquid (meaning water that's been altered so it freezes at temperatures below 32°F). The system fills the walls surrounding the food pans with liquid. Refrigerant lines run through the liquid, chilling it so the liquid chills the food pans in turn.

A big advantage is that neither system needs a defrost cycle. The temperature of the coolant stays more consistent and there's no frosting of refrigerant lines. Another plus is that this type of system doesn't use fans, which eliminates the possibility of spills damaging fans or components. No air vents around the pan recesses also means the liner is easier to clean.

Refrigeration for the storage space in the base of all prep tables is traditional, however, and does require fans. But manufacturers are using more energy-efficient fan motors and compressors these days. While cold prep tables aren't yet part of the Energy Star program, innovations such as the glycol and eutectic liquid coolant systems, independent controls for raised rails (more about this later), and temp sensor defrost have made them more efficient over the past few years.

Design And Construction
While we're still on the subject of refrigeration, there are a few other points you should keep in mind. Product that creates a lot of airborne particulate (flour, in particular, from working with pizza or baked goods) will have a more adverse effect on the performance of an air-cooled pan rail than a mechanically cooled rail. Air-cooled systems are fine, but your employees will have to pay special attention to cleaning the condenser coil and even fan blades.

Compressors also have to work harder in tight spaces where access to cool air is limited. Cold prep tables are often designed with the compressor on the side or in the back of the unit. Models with side-mounted compressors allow you easy access to refrigeration components and the compressor easy access to kitchen air. However, you'll give up some space, usually anywhere from about 13" to 18".

Rear- or bottom-mounted compressors let you save some space, but make sure the unit is "front-breathing," accessing and exhausting air from the front and bottom, before you place it in tight quarters. Condenser coils (usually air-cooled) also need breathing room, and should be easily accessible for cleaning.

Construction also must adhere to NSF standards, but manufacturers can use a range of materials. Manufacturers typically fabricate visible exterior surfaces with stainless steel and use galvanized steel for bottoms and backs. Remember that the heavier the gauge, usually the sturdier the construction. You'll see models made with everything from 16- to 20-ga. steel depending on the maker and the part (lids, for example, often are made of lighter-gauge stainless). Most heavy-duty prep tables, however, are constructed primarily of 16- and 18-ga. galvanized and stainless steel.

Most units have a minimum of 2" of foamed-in-place polyurethane insulation, which helps them meet NSF requirements and makes them more energy efficient. (Solid-top refrigerated prep tables, in fact, now must meet the same new DOE efficiency requirements as any other undercounter refrigerator.) Some manufacturers also insulate the lids to their refrigerated wells, a feature which lets you store product in them overnight.

Cabinet interiors are in most cases made of molded ABS plastic, anodized (or painted) aluminum or stainless steel. All are easy to clean and relatively durable. In general, molded plastic is for lighter-duty applications and tends to be more economical; stainless offers exceptionally long life under harsh conditions but is more expensive. Aluminum falls somewhere in between in terms of durability and cost.

Manufacturers typically offer one or two adjustable wire shelves per cabinet door. These may be stainless, but are usually coated with enamel, PVC plastic or powder paint. Interior capacity may be a factor you want to consider. Cubic footage inside the cabinet can vary widely from one model to another of similar size. Interior cabinet dimensions could be even more important to you. Some models accommodate full sheet pans (and even offer tray slides as an option). Most equipment makers assume employees will simply store food pans from the refrigerated well or rail on the wire shelves.

Another area where dimensions may influence your decision is pan depth. All of these units accommodate 4"-deep food pans, and many models are designed to hold 6"-deep pans. A few models are built to accept 8"-deep pans. Obviously, the deeper pans can hold more food, a plus in higher-volume operations. Some manufacturers also offer you a choice of plastic or stainless food pans.

You're In Control
While we know how important price is in your purchase decision, control can be a big issue in a lot of operations. Base models, like a lot of other refrigeration equipment, are factory preset to maintain proper temperatures per NSF standards (33°F to 41°F). All you do is plug in the unit. More control, however, can give you greater operational flexibility, may save you in energy costs, and could prolong the life of your equipment.

On several raised-rail and a few flat models, manufacturers give you the ability to turn off the refrigerated well. That saves you money at night when the prep table isn't in use.

Some models also offer separate thermostat controls for the base cabinet and the cold well. That can give you a little more flexibility in holding temperatures based on the food ingredients you have stored both in the base and the cold well.

Base models typically offer automatic defrost cycles for both the cabinet and refrigerated well (if they're on separate refrigeration systems). These timed defrost cycles are factory preset.

Another solution that some manufacturers have introduced on recent models is adaptive defrost cycles instead of timed cycles. On these refrigeration systems, sensors on the evaporator coil start the defrost cycle when the coil begins to frost.

A number of models, however, offer a manual defrost cycle for the refrigerated rail. The cabinet refrigeration system is still defrosted automatically, but you can wait until the end of the day to defrost the refrigerated rail after employees have put away the food in the well.

A feature that most manufacturers also offer now is press-in gaskets. The magnetic door gaskets on the cabinets of most units should be changed about every 18 months because they become inflexible and less effective at sealing the door properly. Press-in gaskets make replacement easy to do, often without requiring any tools.

Equipment makers also offer a host of options that can help you customize cold prep tables to your operation. Popular options include shelving for dry ingredients; refrigerated-drawer modules instead of cabinets; legs instead of standard casters; adjustable pan or tray slides in the cabinet; door/drawer locks; and cutting board extenders as well as a choice in cutting board material (poly is standard) such as composite or antimicrobial.

Several manufacturers provide ways to tie their prep tables into your remote refrigeration system, or offer remote systems of their own. Remote systems often provide energy savings over self-contained units.

And a few manufacturers offer two-tiered refrigerated-rail prep tables to double capacity, or two-sided prep tables to potentially double output by allowing employees to work both sides of the table.

At least one manufacturer also offers refrigerated prep tables with a built-in cold top, meaning the stainless work surface also is refrigerated.

Finally, if you can't find a prep table that works for you among all these different configurations, most manufacturers are willing to work on a custom solution.

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