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By Mike Pehanich, Plant Operations Editor | 03/10/2008
Who said processing innovation is dead … or even slumbering? Concerns over energy costs and greenhouse gas emissions are motivating improvements to the food industry’s ubiquitous thermal processing systems. From creative heat-transfer systems and hybrid – and combo - heating processes to whittle at process times, innovation is finding its way into more of today’s processing equipment.
“With the rising cost of energy, processors are looking for any way they can increase the thermal efficiency of their processing systems, and often this involves simply using otherwise wasted energy,” says Don Giles, director of sales for Heat and Control’s Processing Systems Div. (www.heatandcontrol.com/processing.asp), Hayward, Calif.
Exhaust heat from heat exchangers, fryers and ovens can be tapped to pre-heat cooking oil or burner combustion air for energy efficiency increases of 3-12 percent. “In some instances,” notes Giles, “the increase in thermal efficiency also can result in higher finished product output if your system is heat input limited.”
Indeed, energy is the big driver in thermal equipment advances. The more heat you can save or recycle, the happier the processor. Same goes for economical heat generation. Thus, heat transfer systems and processing equipment and lines that incorporate multiple heating methods to cut process times and costs are headline developments.
Richard Magoon was swimming underwater during a vacation in El Salvador, pondering the refractance in a plastic bag on the surface when the idea hit him.
Note to Quality Control
Pressure to reduce energy costs is making many hybrid and alternative thermal processing methods attractive. Watch carefully that product run on any new system is cooked thoroughly and is safe to eat, of course.
The addition of microwave systems, which may save on cooking time and energy consumption, may add a heating variable particularly worth watching.
“I could see the object in the bag, but the rest was indistinguishable,” recalls Magoon. “That was when I first saw the refractance window, the refractance of the air/water interface.”
If you have water on both sides of a transparent medium, you open a window for a ray to pass through that surface, Magoon explains. Therein lies the principle behind the now patented drying technology of his company, MCD Technologies Inc. (www.mcdtechnologiesinc.com), Tacoma, Wash.
The drying process he pioneered directs infrared radiation (or “ray-form energy”) at the speed of light directly into a product or liquid slurry. Evaporation is the result of infrared and conducted heat energy. Adding water on both sides of a transparent medium opens a window in that material for the ray to pass through the surface. “By doing that, you can be very efficient and produce a higher quality of product,” he explains.
Applicable to the drying of fruits, vegetables, fish, meats, cocoa, coffee and many more products, the process is highly efficient and enables a processor to dry product at temperatures as low as 140°F. The result is superior color retention, nutrient quality and aroma. “The quality compares to that of freeze-dried foods. But it dries at low temperatures, rarely over 160°F, and often not even near that.”
Capital and operational costs are the big story. The equipment costs roughly one-third as much as freeze-drying equipment, and the energy used is about one-third as well.
“We have a very energy-efficient and low-cost piece of machinery that provides an extremely high quality product,” says Karin Magoon, MCD president, noting the system’s 96-99 percent efficiency in energy transfer through the refractance window. It requires only 1,200-1,400 BTUs per pound of water evaporated. The best freeze-dry system performance takes about 3,400 BTUs. Air and spray dryers range from 4,000 to 5,000.
“The U.S. Navy uses a dried egg product made by one of our customers for its submarine fleet, and it’s indistinguishable from fresh scrambled,” she says.
So far, the technology has been used to dry algaes (for biodiesel fuel and nutraceuticals) and fish, among other applications. According to Karin Magoon, the USDA has funded a project using one of the MCD units to protect color and anthocyanins (antioxidant phytonutrients) in drying Alaskan blueberries. A processor in Newfoundland also uses it for berry drying. But the Magoons insist the process can be used in any type of product in liquid or slurry form, singling out cocoa and coffee for particularly good results to date.
“It’s a continuous process, too,” adds Richard Magoon. “Material goes in one end and out the other in a short period of time.”
Shaking up retorting
John Emanuel thinks he’s found the biggest thing in retort processing technology since Nicholas Appert invented canning to feed Napoleon’s army.
The history of thermal processing of prepared foods has been largely incremental, says the chairman of London-based Utek Europe Ltd. and a vice-president of Utek Corp., its counterpart in the U.S. But the Shaka process, (www.shakaprocess.com) developed by Utek’s client, Zinetec Ltd. of the UK, can sterilize a variety of products in 6-12 mins. (heat, sterilize and cool). Conventional retort processes typically take an hour or more. The Shaka system provides the product protection and shelf-stability of traditional canned, bottled or pouch-packed products.
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