Equipment: Microwave ovens

Wednesday 20th June 2007 12:51

The ability to accelerate food reheating has made the microwave ovenindispensable for food service operations. But will recent improvementsextend the technology's appeal? Bruce Whitehall examines current options

When they first appeared back in the 1950s, microwave ovens were used in catering. And established attitudes still linger, in that this remarkably fast method of heating food is mainly limited to defrosting and regenerating precooked portions and convenience foods, plus applications such as grab-and-go vending. The emergence of gastropubs, seeking speed and variety with limited kitchen space, could change that.

James Judd, who has sought to turn the Four Winds pub in Belbroughton, near Kidderminster, Worcestershire, into a dining destination since taking over two years ago, sees microwaving as the key to fresh food delivery.

"We prepare our sauces daily and don't freeze them," he says. "But I don't like to keep them hot on a bain-marie it would just compromise their quality and make them more likely to dry up."

So the Samsung CM1929 microwave ovens in the Four Winds kitchen are used to bring portions of fresh sauce - such as the "creamy, minty gravy" which accompanies the signature dish of Belbroughton lamb - quickly up to temperature immediately before service.

The ovens are also used to finish the daily choice of three fresh vegetables and for quick heating of traditional hot English desserts such as treacle pudding. Judd looked at other options, notably combi-steamers, but was not convinced. "They can be 10 times the cost of the Samsung and take up a lot of space - and they still won't be as fast," he points out.

Italian classics

Another catering business that sees microwave power as central to a quality, home-style menu is Ponti's, the chain founded in the 1960s which today has 32 Italian caffès and restaurants around London. "You would be hard pushed to find a heavier user of microwaves than Ponti's," says operations director Stefano Ispani.

Most Ponti's outlets have a bank of 6-8 ovens, typically Sharp R24AT models supplied by RH Hall. These play a key role in regenerating all the chain's traditional hot dishes, such as lasagne and spaghetti bolognese, which are either cooked fresh daily on the premises at each restaurant or delivered chilled from Ponti's central kitchen facility in Islington, north London. Despite their 1,900W rating, the ovens have one of the smallest footprints available and operate off 13amp plugs. They are also stackable, saving valuable space for preparation behind the serving counter.

Important fitments include preset touch controls - with up to 20 available to cover menu needs - and an auto-repeat function. Ispani also likes the "countercheck" facility on each oven, which allows Ponti's managers to monitor the number of dishes prepared on each preset and quickly check the popularity of key dishes without needing to keep manual records.

Minimum intrusion

Another factor that has encouraged wider usage of microwaving has been the relatively less-intrusive nature of the cooking process compared with hobs and fryers. With busy food service outlets directly adjacent to retail departments, Marks & Spencer has been particularly concerned to minimise food smells, particularly at its emergent Hot Food To Go counter-service concept geared to quality fast food.

Combination microwave-convection ovens directly visible to customers have played a major role. At M&S Milton Keynes, fast counter service of fresh-cook items such as pea and asparagus risotto and hot wraps is achieved within 90 seconds using a bank of six Merrychef EC402S ovens. The back-of-house area also has four Microcook HD1925 microwave ovens to heat soups, noodles and porridge portions.

"Advances in accelerated cooking have given us greater scope for developing the hospitality offer in all our stores," says Simon Lushey, senior food technologist at M&S. "The 402S eliminates all food smells, allowing us to locate hospitality areas close to textile departments."

The hybrid convection-plus-microwave ovens resolve such issues with catalytic converters, which, in effect, recycle exhaust air, thus eliminating the cost and complications of fume-extraction hoods. The convection fan pulls in air through the grease filter, which removes the majority of smoke from the air flow. The air is then heated and returned to the cavity through the catalyst and impinger plates to produce an even heat pattern in the oven.

Another issue for M&S is the ovens' simplicity in use. "We don't employ chefs, and staff turnover in the retail sector is traditionally high," Lushey points out.

The latest Merrychef control panels allow operators to store and select 16 product categories, each with up to 16 food products, that is up to 256 programmes in total, each with six stages (temperature, fan speed and microwave power in 10% increments). Cooking programmes are downloaded and uploaded using Merrychef's new MenuKey2, which also downloads updates for the operating software in various languages.

The control also has a dedicated cool-down mode where ice can be used to rapidly cool the oven at the end of the day. The resultant steam aids the cleaning process. Ovens also have an error-monitoring system that flashes up error messages, for example if the magnetron fails or if an air filter requires cleaning.

Electrical challenge

Catering usage of hybrid convection-plus-microwave cookers has grown significantly in the past decade, but the concept actually dates back to the 1960s, with British railway catering being a pioneering application.

On-board cooking technology continues to evolve. Virgin Trains, which uses Sanyo combi-microwave ovens for fast service of freshly baked pies, pasties and sausage rolls, recently resolved a significant issue arising from momentary power outages caused by the electrical cut-off points that occur inevitably in electric train operation.

Whenever such breaks occur, microwave oven timers return to zero - just like many domestic appliances following a power cut - which can be frustrating for staff and customers on a busy inter-city train. Until recently, the only option has been to restart the programme from the beginning, with the risk of over- or under-cooking products.

Valera, which supplies Virgin's ovens, resolved this problem with a "train-friendly" version of its Sanyo EMCD2900 combi-microwave. An inbuilt "brown out" facility now simply pauses the timer rather than resetting it whenever an outage occurs. It automatically continues from the stopped time once power is restored, avoiding food wastage and queues. Virgin has ordered 40 of the ovens.

Combining heat sources

The growing choice of options in combi-microwave ovens is demonstrated by recent extensions of the Amana Convection Express range, supplied by Bradshaw, and the Whirlpool range available through Equip Line. There has also been ongoing development of the US-made TurboChef oven, where a moving hot-air "shroud" combines with microwave energy and specialist heat transfer through the top and bottom of the food to boost cooking times by up to 12 times.

Acceleration of other types of heating process by "bolting on" microwave technology continues to attract attention, in combi-steamers, conveyor ovens and even commercial laundry equipment.

According to Gordon Andrews, head of GAMA Microwave Technology, a specialist consultancy with more than 30 years' development experience, there is still a major challenge: developing a standard system of microwave coupling which can be fitted to any size of oven, without a lot of customising, to resolve variations in energy-pattern distribution.

GAMA believes it might have the answer with its "multi-entry-mode resonator" (or mode resonator for short). This is designed to obtain uniform vertical and lateral heating distribution regardless of shelf position or whether metal utensils or shelves are used in oven cavities.

This opens the door to performance improvements in ovens that combine microwave energy with steam, and in applications such as baking, using fresh or frozen raw dough, where conventionally applied microwave energy tends to harden breads and damage delicate pastry products.

The latest outcome is a counter-top oven - not yet available but currently on UK trials - which is able to fresh-bake croissants, cinnamon rolls or garlic bread in less than two minutes and cook hot breakfast dishes such as sausage muffins in one minute 20 seconds.

Key maintenance points

• Most importantly, buy a commercial oven. Domestic ovens simply cannot cope with constant use. They will overheat quickly and can fail to reheat food adequately, possibly causing a food safety risk.

• Don't put anything on top of the oven or block the air vents. Maintain an air gap around the oven sides and back.

• Avoid slamming the door, as this will cause damage to the interlock safety mechanisms, which prevent the emission of microwave energy while the door is open.

• Microwave ovens and microwave combis create radiation within the oven cavity, so an annual check using a microwave leakage tester is essential to ensure that there are no leaks.

• Clean out spillages from the oven immediately. Food waste might ignite if reheated constantly.

• Check your manufacturer's instructions for the correct cooking containers for use in your oven. Metal containers can cause damage to the magnetron.

Source: Serviceline (01438 363000)

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