The mandate is to deliver safe, consistent, uniform products.

IT SHOULD BE NO SURPRISE. THE NUMBER ONE ISSUE DRIVING innovation in oven and dryer technology is also the number one concern of food processors across the globe: food safety.

When the talk is about ovens, food safety means fully cooked product.

"All food manufacturers want assurance that they are achieving a core temperature that will produce a pathogen-free product," explains James Padilla, director of product development for Heat & Control, Inc., Hayward, Calif.

Of course, no processor wants meat products that look like charcoal briquettes coming off the line. Uniformity and consistency are the watchwords of the day. The mandate is to deliver safe product and a whole lot more - high quality, good taste, moisture retention - produced at the lowest possible cost.

A flawless system able to monitor the internal temperature of each and every product in real time is today tantamount to the Holy Grail. But it may not be too far away. Prototypes for smart heating systems are already under development. (See sidebar on page xx.) What makes their appearance likely in the near future is growing evidence that more processors may be willing to pay a higher ante for food safety and quality.

The AeroPulse™ is a pulsed-fluid bed drier that delivers air sequentially along the drier, up through a perforated product bed to fluidize the product. The airflow and pulse frequency are variable to ensure that the fluidized product flows and acts like a fluid. Source: Aeroglide.

Not just hot air

Processors of poultry products, meat patties, sausages, pizza pockets, egg rolls, and hundreds of other products susceptible to food borne pathogens are well aware of the health risk posed by undercooked product. Monitoring the core temperature of individual products only maximizes detection of non-pasteurized product. Ovens that cook uniformly and consistently are the first priority.

"Processors are driving for consistency of product," notes Jan Gaydos, director of marketing and the Food Processing Tech Center of FMC FoodTech, headquartered in Chicago. "They want assurance that cooking is uniform in their oven, top to bottom, side to side. And they want a repeatable result through the production day."

Uniform airflow is critical to consistent cooking. An oven with cold spots may leave some product dangerously uncooked. To effect consistent cooking regardless of a product's belt or oven position, manufacturers strive to balance airflow and to eliminate hot and cold spots in the oven.

"We are refining air balance and air management to assure that the product on the left side of the oven has the same core temperature as product on the right," says Gaydos. "We are also keeping more moisture in the product. Yield is the name of the game. Moisture inside the product is as important as adequate cooking."

Hot humid air is uniformly applied across the full width of the product conveyor (1) in the AirForce Impingement Oven from Heat and Control. The return path of air (2) between impingement nozzles does not interfere with incoming hot air. Centrally located fans (3) force air evenly through nozzles above and below the product. Source: Heat and Control.

Oven innovation

FMC manufactures both impingement linear ovens and spiral ovens through its Stein unit. Its GCO GYRoCOMPACT is a space-saving spiral oven with a self-stacking belt. "It provides a lot of belt area in a very small footprint," says Gaydos. It serves best with higher capacity runs and products requiring longer cook times.

Its top-of-line linear oven is the Stein Jet Stream Oven (JSO) which employs thermal fluid heat and a heat exchanger. Its JSO4 model employs technology similar to its fryer line.

"With thermal fluid heat, you don't have the high temperature shock you get with gas jets, which can cause a phenomenon called ‘pinking,'" says Gaydos.

It's hard to believe, but used air can be a big deal. Returning air can disrupt an oven's primary flow of heated air. Heat & Control's AirForce Oven generates pressure to create uniformity in the plenum, according to Padilla. "By putting fans inside the pressure plenum and housing fans underneath the nozzles, we can generate pressures where we want," he says. "We have designed a return path so that we have controlled uniform air above and below the belt."

B.N.W.'s new Spirajoule technology uses a heated, coreless screw made for optimal thermal transfer to a wide variety of wet and dry products. "A processor can run the screw to temperatures of 200

Spirajoule technology from B.N.W. uses a heated, coreless screw made for optimal thermal transfer to a wide variety of wet and dry products. Source: B.N.W. Industries.

Control thing

Sophisticated control systems have given the biggest boost to oven consistency and data capture. "The key is the ability to control the moisture percentage by volume and to have a repeatable setting," says Padilla.

"Data loggers are coming of age," says Jim Porach, sales director for Cleveland-based The Lanly Co. "You can record temperature and air flow throughout the oven and get an accurate reading of what is really going on in your oven."

Effective, thorough data collection can capture ideal cooking parameters so that the best product possible can be produced again and again. Such data collection can also yield valuable documentation of a production run. Electronically captured data is easily fed back to corporate offices for reference if a recall or question about cooking arises.

Another advantage of modern controls and data collection capability is increased flexibility. "Flexibility is built in," says Porach. "If you have the data profile (for a product), you can make adjustments to the equipment and run the product with multiple systems and still get the exact result you want."

Computerized process control enables processors to link ovens with other equipment components up- and downstream in the production line and to compare historical data.

"Batch processing operations have generally had the more advanced control systems, but controls on continuous processing lines are really gaining ground in the industry," says Gaydos.

Lower cost and growing familiarity have made many modern control amenities seem more desirable. Lanly's Porach thinks that new touch screens and other bells and whistles are now attractive enhancements.

"Foo-foo sells," he says. "People like the advantages of friendlier systems. And today they'll pay for it."

Large multi-pass commercial dryers are pre-engineered to satisfy the sanitation and cleaning challenges associated with fruit products. Dryer features can include clean in place wash station, sloped internal surfaces/floor, and additional access doors. Source: Wenger.

Out to dry

Perhaps the most significant development in dryer technology has been the integration of the dryer into the total processing system. No longer is it regarded as a piece of stand-alone equipment.

As with oven technology, the most notable refinements revolve around controls. "Keeping air-flow constant and temperature variation down to a bare minimum translates into a uniform product," says Tom Schroeder, president of Cincinnati-based Ventilex, a manufacturer of fluid bed processors.

Today, microprocessors and PLCs offer features and capabilities that simply weren't available just a few years ago. The refinements have appeared not just in the electronics but in their implementation, too.

According to Schroeder, some of the advances in dryer and conditioner technology have been dramatic. Cheese dehumidification, for example, can now meet stringent temperature requirements with accuracy up to one or two degrees while maintaining proper moisture requirements.

Schroeder, whose company last year built the largest ever fluid bed dryer (a 310-sq. ft. single fluid bed unit), credits "fast acting RTDs," resistive thermal devices, implemented in various sections of dryers for improved ability to predict drying results. Advanced modeling software built into PLCs also has enabled processors to maximize dryer throughput.

Similarly, Aeroglide, Raleigh, N.C., introduced the AeroFlow fluidized bed drier and toaster. Touted as ideal for cereal processing, it is designed "to make product flow like a fluid," according to Patricia Sharp, marketing manager. An air impingement system, forcing air through a perforated bed at high velocity, lifts and separates product, creating an air envelope that enables more efficient moisture removal. It is touted as ideal for cereal processing.

The AeroPulse Pulse Fluid Bed Dryer is a patented technology introduced last year. The system introduces sequential pulses of air through a perforated bed. Controlled airflow and pulse frequency keep product fluidized, reducing the time required for moisture removal.

"Pulsed air fluidization requires 30- to 50-percent less air than a conventional fluid bed dryer," claims Sharp. "It shoots jets of air up through the product bed rather than down upon product. Plus it is pulsed, keeping the product fluidized."

Aeroglide also has added major sanitation upgrades to its conveyor dryers. New designs feature smoothed surfaces that eliminate corners and pockets where food can collect and create a sanitation hazard. Design changes also include more access points to simplify cleaning and sanitation steps.

Cost control

Equipment manufacturers have taken food processor's cost reduction concerns very seriously. Most of those changes have been design alterations or control changes to make equipment more flexible and to improve control over the process.

"Most of the innovation in recent years has aimed to reduce the cost of capital equipment," says Doug Schieber, sales manager of Carrier Vibrating Equipment, Louisville, Ky.

The abundant availability of 2-B stainless steel sheets is another reason costs on many ovens and dryers have come down over the past five years. With its sanitary finish, 2-B stainless is a highly sought commodity for food equipment makers.

Marketing energy efficiency and sanitation

Rising fuel costs have made energy efficiency an important piece of the equipment payback equation.

"Energy efficiency is important to our new ASR (Adiabatic Saturation Ratio) control system," says Robert Sunderland, dryer applications specialist for Wenger, Sabetha, Kansas. "We control the amount and quality of air leaving the dryer so that the dryer is running as efficiently as possible."

Attention to cleaning and sanitation has been another noticeable trend of recent years, according to Sunderland. Some are simple matters of engineering or design, such as placing an augur in a horizontal area where food particles might collect. But there's evidence that sanitation is important enough today to loosen the purse strings.

"Customers are more willing to spend capital dollars up front to design around sanitation issues," says Sunderland. "Processors are willing to spend more on internal cleaning mechanisms than they have in the past."

For more information:
Aeroglide Corporation, Patricia Sharp, 919-851-2000;

B.N.W. Industries, Aaron Norris, 574-353-7855;

Carrier Vibrating Equipment, Doug Schieber, 502-969-3171;

The Lanly Co., Jim Porach, 216-731-1115;

Ventilex, Tom Schroeder, 513-366-3950;

Heat & Control, James Padilla, 800-227-5980;

Wenger, Robert Sunderland, 800-833-0174;

FMC FoodTech, Jan Gaydos, 419-627-4303;