Caterer and Hotelkeeper – 28547

What to look for

Continuous improvements in technology have steadily widened the microwave oven's potential, giving the chef new creative scope as well as enabling single portion meals and snacks to be reheated reliably at speeds unmatched by any other appliance.

As well as the ability to match many jobs closely, microwaves also offer significant energy savings since there is no warm-up time and energy is only used when the food actually needs it. Microwave ovens also help the kitchen stay cool.

The choice of oven from the dozens of commercial models now on offer relates basically to a series of key variables.

Power rating. In basic terms, the greater the output, the faster the speed of reheating. Commercial microwave ovens conform to a standard system laid down by the IEC international electrical standards organisation which quotes microwave output against specific tests in watts; commercial models range from 700 watts to 2,200. In basic terms, the greater the output, the faster the speed of reheating (twice as fast if, say, comparing a 2000 watts oven against a 1000 watts model).

Cavity dimensions. Where single portion foods are handled, a small cavity has the edge in terms of speed (and will probably make for a more compact installation). However, larger sizes have the advantage of taking more than one container at a time, either side by side or stacked. Some large cavity ovens can be fitted with a shelf and are better suited to taking more than one container at a time, either side by side or stacked. Some very large versions now available are sized sufficiently to hold a full 1/1 gastronorm pan. Where single portion foods are handled, a small cavity has the edge in terms of speed and compactness.

Energy distribution: microwave heating involves the production of invisible waves of electromagnetic energy by a magnetron, siting of which varies from model to model. This energy passes at very high speed into the cavity via a waveguide or stirrer fan where it bounces around in all directions and becomes absorbed by the food to a depth of 1.5-2 inches. This causes the food's moisture molecules to vibrate against each other and it is this friction which heats the food. The pattern of wave distribution in a commercial microwave is such that turntables, as found on domestic models, are not necessary, making for greater space and easier cleaning.

Door design: several configurations are available on catering models: side-hinged is most common; a minor potential snag is that, over time, wear and tear can cause it to become misaligned. Pull-down and pull-up types spread the weight of the door more evenly; the pull-down variety provides a flat surface in front of the oven when loading and unloading. Pop-up doors open automatically when the cook time is reached and they also save space where gangway space is tight. Most microwave oven doors are fitted with glass to permit inspection of food in the illuminated cavity.

Controls: this has been a major area of oven development. There are two main options in timers. Dials enables any time (up to, say, an hour) to be selected but the more typical option today is a series of presettable buttons or touchpads enabling regularly-used timings to be memorised. With both types of control, the microwave automatically switches off when the time is up.

A separate control enables power level to be set, either in basic modes like full power, half power and defrost, or in stepped increments of, say, 10 per cent. Reduced power is helpful on delicate work such as fish baking while very low settings suit process jobs like softening butter or tempering chocolate.

Some ovens have a button which recomputes the time for double quantities and some vending microwaves have counters showing throughput by product.

Combi-micros

An increasingly significant variant of the basic microwave oven, the combi-microwave oven employs the same basic energy system, but in combination with conventional heat-up elements and a fan to waft the heat around the cavity, which is typically larger than on a regular microwave.

The convected heat can be used on its own but the real benefits of fast baking and roasting - jobs to which the standard microwave is not well-suited - come when the two power sources are used together. Some combination ovens also have an infra-red grill bolted to their roofs to provide one further cooking mode.

Combination microwave/ convection ovens are better suited to prime cooking because the additional convected hot air and/or grilling available is able to browning and crisping. It also becomes possible to cook large joints or several items at the same time without having to increase times to the extent needed on conventional microwaves.

An important recent development in microwave technology is to "turbo-charge" other types of oven such as baking ovens and combi-steamers by incorporating microwave capability within the cavity. This is found on the Micromax launched this year by Leventi.

The US company Turbochef Technologies has also created a lot of interest in multi-purpose, ultra-fast ovens which links microwave with specialist thermalisation technology.

What to buy

Microwave ovens

Standard models for reheating and vending applications with presettable power levels and timing programmes. GN=cavity sized to take Gastronorm pans.

SUPPLIER MODEL OUTPUT POWER PRESETS GN? LIST

watts LEVELS PRICE

from

Apuro/Samsung CM1229 1200 5 30 2/3 895

Apuro/Samsung CM1429 1400 5 30 2/3 1045

Apuro/Samsung CM1829 1800 5 30 2/3 1195

Electrolux MW1210 1200 10 20 no -

Electrolux MW1710 1200 10 20 no -

R.H.Hall/Sharp R21AT 1000 10 20 no 499

R.H.Hall/Sharp R22AT 1500 10 20 no 899

R.H.Hall/Sharp R24AT 1900 10 20 no 1199

Hobart M1600T 1400 10 10 no 1100

Lincat MW2 1000 3 Man no 540

Merrychef Microcook 1025 3 10 no -

Merrychef Microcook 1425 3 10 no -

Merrychef Microcook 1725 3 10 no -

Merrychef Microcook 1925 3 10 no -

Merrychef Microcook 2025 3 10 yes -

Panasonic NE1456 1400 3 20 no -

Panasonic NE1856 1800 3 20 no -

Valera/Sanyo EM-P1010 1000 10 10 no 449

Valera/Whirlpool AVM825 950 10 10 no 599

Valera/Sanyo EM-C950 900 5 5 1/2 599

Valera/Sanyo EM-C1100 1100 10 10 1/2 699

Valera/Whirlpool AVM502 1200 10 20 1/2 899

Valera/Sanyo EM-C1400 1400 10 10 1/2 1049

Valera/Whirlpool AVM503 1700 10 20 1/2 1199

Valera/Sanyo EM-C1800 1800 10 10 1/2 1249

Valera/Sanyo EM-C2001 1900 10 10 2/3 1449

Zanussi ZA1500 1500 10 20 no 1150

Zanussi ZA1800 1800 10 20 no 1250