Guest Column

Smart heat

The position of heating elements and the thermostat sensor controlling their performance in heating equipment causes variations. It's an inherent problem in every conventional griddle - gas or electric, says M Ram Vittal Rao.

Equipment selection is a science; it cannot be done just by walking into a facility. Right-sized equipment which actually fits in with the operator's equipment with good work flow is key to any facilities' success. There is always a fine line that is drawn when consultants select equipment. The tussle is branded versus non-branded.

As a member of FCSI, news of many developments in foodservice technology floats across one's desk. FCSI members are responsible for sorting out these new technologies to create an ideal environment for preparing food, which optimally satisfies their client's specific requirements. As per rule, we always use numerous criteria in determining what equipment best suits a given project's needs, size, initial cost, reliability, clean design, safety, performance, operating cost, and overall user-friendliness.

My principal efforts are devoted to developing the best-performing kitchen possible for Friendly's Restaurants - a regional 800-unit combination coffee and ice cream shop chain. Its operating realities are strongly influenced by high turnover labour pools, pressure to reduce operating costs and a desire for increased cooking process, simplicity, consistency, and reliability in the smallest possible area.

Towards better engineering

In the past, the foodservice industry has made great strides toward the better engineering of various menu products (consistent frozen patties, unique processing, innovative packaging, and a wider variety of taste and texture choice), so it seemed appropriate to reconsider the engineering of the appliances used in the final preparation stages of these improved items. Of Friendly's 800 kitchens, in excess of 700 are all-electric, with the old GE griddle the accepted standard in most.

Griddle technology has remained stagnant for years, with only enhanced controls, better construction materials, and better heat distribution as developments of any significance. Unfortunately, the major equipment "enhancements" brought with them higher costs and more complexity. In spite of feedback from restaurateurs for new cooking equipment addressing their most pressing issues, there have been no significant operational breakthroughs.

However, a new grill heat transfer technology developed by Metcal Inc. brings some fresh tidewater into the food service sea. Before I describe this new development, I'd like to explain why I feel that the present conventional all-electric thermostatically- controlled griddle technology is inadequate.

Testing of the classic GE electric griddle revealed the following results:

• The typical temperature variation within the prime central cooking zone exceeds 110ºF during a typical full load cooking cycle (thermal regulation exceeds + 50º F).
• Cooking consistent product (the same mass of product with the same bulk temperature, at the same grill location to the same level of doneness) requires a widely variable rate of power consumption from batch to batch. A range of between 0.15 and 0.35 Kw was consumed for the identical thermal mass batches under similar operating conditions.
• A temperature variation of 76º F within a central cooking area is experienced under non-load conditions (thermal regulation exceeds + 38 ºF).
• For an identically timed cooking cycle, a frozen quarter-pound hamburger may be grilled to rare, medium rare, or medium within the same batch of patties. Even worse, consecutive batches may range from rare to medium well.

The positioning of the heating elements and the thermostat sensor controlling their performance cause these variations. It's an inherent problem in every conventional griddle- gas or electric.

In addition to the above concrete results, I have postulated three conclusions: firstly, griddles, which perform well on one criteria sacrifice quality on another. Secondly, for some criteria, like temperature consistency, none perform ideally, and there is only a choice from the "lesser of two evils" -poor sensitivity and dynamic response or high thermal gradients. And lastly, although manufacturers have come out with various bells and whistles such as digital controllers and easier to clean surfaces, these have provided little change in overall performance cooking consistency, especially when one factors in variable demand (time of day and product mass).

After re-examining Friendly's griddle performance profile and literature describing Metcal's patented design features, I elected to visit Metcal Inc in Menlo Park, CA, to test its new 'Smart Heat' Convertible Grill. After some initial wariness, I discovered that this grill really offers some new features, innovative concepts, and sound solutions. For example, after the grill is turned on, it reaches operating temperature in only two minutes.

There are no thermostats, sensors, or heating elements, yet the grill surface maintains consistent temperature + 3 F within 2" of the edge of each cooking zone at idle. How is this superior performance achieved? The Metcal proprietary heating technology is simply based on physics principles that are over 50 years old yet is radically different from any technology used in the foodservice market today. Metcal has unleashed the physical properties of the grill surface itself to self-regulate around a designed-in temperature. This concept has been used in commercial electronics, medical equipment, and soldering systems for a decade.

Magnetic Metcal

Unfortunately, its self-regulation principle is not as readily described as operating the grill. Simply stated, the Metcal Convertible Grill is based on the principle that magnetic materials will self-heat when placed into and inductive field. The more magnetic the material is, the faster the heating, and conversely, the less magnetic it is, the slower the heating.

Metcal's unique grill surface changes its magnetic properties by itself. When the grill surface is below the desired set temperature (Curie point) it is highly magnetic and instantly draws power only to those spots not at the set point. As the surface approaches its predetermined set temperature, the material becomes less magnetic and stops heating entirely when the Curie Point is reached. As a result, when a load is placed onto the surface, it instantly starts recovering (drawing power) and once at temperature stops drawing power. It can't create a hot spot as only cold regions draw energy. This means that it is physically impossible to overdrive a properly constructed Metcal grill plate!

This self-regulating effect is one of the physical properties of the ferromagnetic alloy that makes up the grill surface. It is not driven by controllers, thermostats or any other device. In fact, the Metcal system has the fewest mechanical parts of nay marketed system. In place of the usual complicated elements, sensors, and dials, the Metcal Grill consists of a power supply, a power switch, an inductive coil, and the grill plate itself. If simplicity is grace, the Metcal system seems graceful indeed.

Beauty in simplicity

This inherent simplicity leads to may advantages over existing griddle designs. Cooking consistency is improved since the grill maintains a truly consistent surface temperature profile over the entire surface when under full, random, or no-load conditions. This is accomplished without any sensors requiring calibration or adjustable dials and switches to set. While cooking, obtain greater effective cooking area from the consistent temperature profile edge to edge.

Since each plate can have its own set point temperature, separate cooking zones are created without any temperature profile migration, providing flexibility for multiple item menus. Power consumption is dramatically lower because power is drawn only where and when it is needed, with thermal efficiencies ranging between 75%-85%. And, when the day is over, clean up is easy because elimination of hot spots means less burned on fat and carbonized material. The grill plate is portable and may be carried to the dish machine if desired.

Test results

• The typical temperature variation within the prime central cooking zone is less than 30°F during one cooking cycle (thermal regulation is less than 15° F).
• Cooking consistent product (the same mass of product with the same grill location to the same level of doneness) requires between 0.14 and 0.15 Kw per batch; a more consistent rate of power consumption than the competitive thermostatically controlled electric resistive element models.
• A temperature variation of only 3°F within a central cooking area is experienced under non-load conditions (thermal regulation is less than 2°F) This is 36°F superior to the current industry standard.
• For an identically-timed cooking cycle, a frozen quarter pound hamburger will always reach the same level of doneness. Convertible technology does achieve this consistency.

In future, Friendly's will be doing extensive testing of a new Metcal 'Smart Heat' Convertible Grill in our R&D test kitchen. If this extended test continues to confirm the internal results of better food consistency, it will be a key element in Friendly's Kitchen of the '90s design activity and presumably make a significant impact on our industry

(The writer is an international hotel design consultant. He has designed over 100 hotels, restaurants, serviced apartments and flight catering projects. A certified professional member of the Food Consultants Society International (FCSI), he teaches hospitality design at The Oberoi School of Hotel Management and at the Taj Group of Hotels: Centre of Excellence)