SPECIAL REPORT: Speed Demons

Lots of equipment makers promise faster cook times. How about three times as fast as conventional equipment? Five times? Fifteen times? Ridiculous, right? Or maybe you’re thinking, sure, your microwave cooks that quickly, but you can’t use it for sandwiches, and it sure won’t bake cookies.

For bigger batches, you often have other quick options. Combi ovens, for example, are fast, and they not only bake cookies, they also can cook french fries and fried chicken. Combi ovens are great—especially if you’re making several pans of food at a time. They’re not that practical, however, for one or two items at a time. More specialized pieces of equipment also can produce food quickly, but often with limited versatility.

So, for those of you who want to speed your production and/or offer a broader menu in a location that isn’t set up for it, dual-tech microwave ovens may be just the ticket. Good examples of candidates for dual-techs are c-stores that want to offer more than hot dogs on a roller grill or movie theaters that want to offer a wider choice than popcorn and candy. Coffee shops, snack shops, retail grab-and-go counters, food kiosks and anyplace that doesn’t have a kitchen can easily produce a wide variety of foods with these marvels. Not to mention a kitchen that just needs some extra oomph and flexibility.

LONG TIME COMING
Also known as combination microwave ovens (“combo” as opposed to “combi” ovens) or accelerated cook ovens, these countertop units have been around for 50 years in varying, largely rudimentary forms.

For pricing, sizing and refinement reasons, however, for several decades they never quite took off. But the basic concepts held promise, and within the last decade, especially, refinements and the advancement of consumer technologies has made these dual-tech ovens easier than ever to operate and more affordable, too. Today, in fact, they’re so fast you can turn out the same amount of food as a much larger conventional oven in the same amount of time.

What makes these countertop ovens so fast? Basically, equipment makers have coupled the speed of a microwave oven with the speed and baking/browning characteristics of a convection oven. And in some cases, they’ve incorporated some other energies too, either for yet more speed or other reasons.

It’s this combination of energy forms that allows speed ovens to cook a wide variety of foods, including pizza and hamburgers, very quickly, all in a minimal footprint. That combination of attributes makes them especially handy for operations that want an expanded menu of items that move at relatively low volume.

Science Behind Speed
Cooking is all about transferring heat to food, and you can accomplish that several different ways. The primary methods are radiant heat, convection heat, conduction heat and microwaves (which essentially cook through conduction).

Microwaves are essentially radio waves with a frequency of about 2.4 gigahertz (a giga is one billion). By comparison, FM radio frequencies start at 88.1 megahertz (one million hertz); television stations broadcast from about 1.6 GHz to 30 GHz; and police radar (Ka band) ranges from 33.4 GHz to 36 GHz.

When microwaves are directed at food, they interact with molecules that have a positive charge at one end and a negative charge at the other. Also called bipolar or dipole molecules, examples include water, fat and salts. The microwaves make these molecules oscillate or rotate (remember making bipole magnets do that in school?), and as they spin they bump into each other. The resulting friction between molecules creates heat, and the heat is conducted throughout the food, heating it or cooking it.

Foods typically cook two to four times faster in a microwave than in conventional equipment, depending on the product. Because microwaves affect dipoles like water molecules, microwaves are most effective at heating/cooking foods with high water or fat content. It also means they’re very effective steamers. (One manufacturer even has a new microwave unit specifically designed as a steamer.)

Microwaves don’t actually cook food from the inside out as is commonly thought. Microwaves do penetrate deeper into food than do convection heat or infrared radiation—several centimeters—but they lose about half their power for every 2 cm (about ¾”) they penetrate. By the time they reach the center of a 6” bird, roast or casserole, for example, they’ve essentially disappeared, transferring all their energy into the food. The interior is cooked through conduction, which is why most microwave recipes have a resting period, allowing time for heat to cook the center of the product.

Radiant heat and convection heat work differently. They essentially transfer heat to the food’s surface, where it’s slowly conducted into the food. Because the food’s surface constantly transfers heat, it cooks more quickly than the interior of the food, which is why foods brown more quickly under radiant heat or in a convection oven.

Best Of Both
By combining microwaves with convection, speed ovens give you the best of both worlds—incredibly fast cooking times with the ability to brown and crisp. And by combining the two cooking types, speed is increased from two to four times faster than conventional equipment to as much as 10 to 15 times faster.

And what comes out of these units is food cooked to perfection—a tender salmon fillet or beef tenderloin in about 3 mins. compared to about 20 mins. to 25 mins. in a convection oven. Juicy chicken breast with a crispy golden brown skin. Cookies with a crisp exterior that are moist and chewy in the middle. Crusty bread with a soft, chewy interior.

The small footprint of most models allows you to put them almost anywhere you’d put a microwave oven (though you’ll generally need 208V or 240V electric service). They fit easily on a counter, but many models have the capacity for one or two half-size hotel pans. And they’re so fast they can cook 10 pans of food in the time it takes a standard convection oven.

Best of all, virtually every model comes with a UL-approved catalytic converter rated for proteins, making them truly ventless ovens. You heard right—no hood required. When we said you can use these in operations that have no kitchen, we meant it. Their plug-and-play technology means you can stick them practically anywhere.

Most manufacturers now offer a range of models, giving you different sizes to choose from and slightly different combinations of cooking technologies, so you’re sure to find one that best meets your needs.

Typically, size of the model you choose is dictated—no surprise—by the amount of food you need to cook at one time. Most operations that purchase speed ovens typically cook one or two items at a time, so they don’t need large capacity. And if they end up turning out higher than expected volume, they tend to purchase additional ovens and stack them instead of buying a larger unit.

As mentioned earlier, several manufacturers have added a boost to the microwave-convection package in some models to either make them cook faster or provide more versatility. Some newer models combine microwave and a form of focused convection called impingement cooking. (Lincoln Foodservice has a trademark on the name Impinger; the industry now generally refers to the type of forced air convection used in Impinger ovens as impingement.)

A few manufacturers have added radiant heat to some models, too, which further speeds cooking. The infrared radiant element in these units also provides more effective browning, which you may want for some menu items.

The newest convection technology available is called “planar plume.” Heated air is directed in planes at angles toward the center of the cavity. The sheets of air collide above the food surface and spread around it. The manufacturer says it’s as effective as impingement at forcing cold, moist air away from the food, and its lower fan speeds reduce noise.

Performance Practicalities
It used to be that the rap on microwave ovens was that they didn’t cook evenly. In the early days, there was some truth to that. But that was true of conventional ovens and then-new convection ovens, too. Fact is, inconsistencies in food thickness, moisture, fat content and density cause most cooking techniques to produce some irregular results from time to time. But time marches on, and refinements in technique have improved cooking results across the board.

Commercial microwave and speed oven manufacturers in recent years have addressed the problem by spreading microwaves more evenly throughout the cavity. Some use a pair of magnetrons and launch microwaves from each side. Others locate the magnetron on the side or top of the unit and transmit microwaves down a “wave guide” into the oven. A few use a “stirrer,” essentially a fan at the end of the wave guide, the blades of which reflect microwaves as they turn, bouncing them into the cavity in all different directions. Others have played with the design of the antenna (some even oscillate), the design and shape of the cavity itself, or a combination.

In general, convected heat tends to cook food more evenly than conventional heat, too. Combining these technologies results in an oven that cooks as evenly as anything on the market.

Another traditional limitation to microwaves has been the requirement for microwave-safe pans or containers of glass, ceramics or certain plastics. Not a biggie, but an inconvenience. Traditionally, metal’s been out because microwaves bounce off metal and could reflect the energy back at the magnetron and damage it, or cause arcing and start a fire.

More recently, though, manufacturers have devised ways to let you use standard metal half-size hotel pans in some (but not all) of these speed ovens. Some have a top-mounted magnetron; if you put food in a metal pan, the pan will act much like the bottom of the oven. Other models launch microwaves from the sides of the oven, so they don’t reflect off shallow metal pans. Be sure to read the fine print, though. Some models claim you can use metal pans, but make it clear that you can only use metal when the oven is in convection-only mode.

Also double-check if you buy a speed oven with a radiant heat element. Generally, you shouldn’t use any type of plastic containers when the browning element is on.

Maintaining Control
In high-performance, high-tech ovens like these—much as in any high-performance machine, whether cars or aircraft or whatever—control technology is every bit as important and interesting as the speed technology.

The cooking options on speed ovens, much as in combis, are almost limitless. Depending on the model (and the number of cooking technologies built into it), ovens may have three-stage, four-stage or even six-stage cooking cycles, letting you control and vary microwave power level and duration, convection or impingement duration, and/or the browning element.

Fortunately, although cooking and other processes can be quite complex, controlling them is simple. All models are programmable, and most come with a number of presets and room for additional menu items. The presets may be general in nature (e.g., “a 6” frozen pizza,” or “chicken breast”), but a least a few manufacturers pride themselves on their culinary staff and their ability to help you customize the oven for your menu items.

The benefit, of course, is that menu items will be cooked the same at any location throughout your operation. Health departments like the preset cooking cycles, too, knowing that each menu item will be cooked consistently and safely no matter who operates the oven.

Most ovens use touch panels that enable you to select presets or program the cooking cycle. Some provide detailed, step-by-step instructions, while others use icons and are more intuitive to operate.

Self-diagnostics are a side benefit of the sophisticated controls. Models typically alert you when air filters need cleaning, for example, and many have auto shut-off safety switches that prevent the oven from operating if the filters are too dirty. Several models can even tell you how long it’s been since you last cleaned or changed the air filter.

Most also give you the option of uploading or downloading recipe programs from or to a USB thumb drive, making it easy to move programs from one oven or store to another. Some models offer Ethernet connectivity, so you can change menu items or add a program to ovens in all your stores at once from a central location.

Cleaning and maintenance is fairly simple for such sophisticated pieces of equipment. There are few moving parts other than fans for the convection or forced air. The oven interior, and racks if the model comes with them, should be cleaned out daily, and the grease/air filter cleaned as necessary. Other than wiping down the exterior occasionally, there’s little else that needs attention.

Check warranties and service networks to be sure you can get the attention you need where your stores are located. And spend time talking to manufacturers about how they can help support your goals with their equipment. Some may turn you loose to experiment on your own, which you may prefer, while others will work with you on menu item development and customizing an oven to suit your needs.

Finally, while speed ovens aren’t inexpensive—list prices range from about $5,000 up to around $13,000—they’re a bargain when you consider that you’re getting almost an entire kitchen, hood included, for that cost. And these units are just about the most energy-efficient pieces of cooking equipment available. Speed, indeed.

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