By Jonny Lupsha, Wondrium Staff Writer
Robert Schiffmann, an innovator in microwave heating technology, has died. While he didn’t invent the household appliance himself, his work led him to invent microwaveable oatmeal, among others. Microwaving differs from all other cooking methods.
The modern microwave oven exists in almost every home in the United States and countless other countries. While chefs often decry it compared to other methods of cooking, there’s no question it’s made life easier for millions, if not billions, of people around the globe. One of the technology’s biggest gurus, Robert Schiffmann, recently passed away at the age of 86. Schiffmann was responsible for microwaveable oatmeal, microwaveable caramel popcorn, and a system to microwave food without removing it from its packaging.
Unlike every other method of cooking, microwaving doesn’t cook food by traditional heat but by energy transfer. In his video series Physics in Your Life, Dr. Richard Wolfson, the Benjamin F. Wissler Professor of Physics at Middlebury College, explained how.
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According to Dr. Wolfson, there’s energy transfer in a microwave, but it isn’t exactly heat because it isn’t flowing due to temperature difference.
“Microwaves cook, ultimately, because the water molecule in particular has a big separation of electric charge, positive and negative, and the oscillating [electric] field of the microwave, […] going back and forth 4.5 billion times per second, grabs water molecules, juggles them all up, and makes that random motion that we call, loosely, ‘heat,’ but that we should call thermal energy.
“The microwave therefore deposits energy in the food, and that energy becomes thermal, what we call ‘thermal energy’ or ‘internal energy,’ in the food.”
If you’ve ever used a microwave, you’ve likely asked why it doesn’t heat evenly all the way through.
The actual microwaves bouncing around in a microwave oven have a specific frequency. Dr. Wolfson said that the frequency is approximately 2.45 billion cycles per second, or 2.4 gigahertz (GHz), which corresponds to a wavelength of about five inches. Since the microwaves reflect off the interior metal walls of the device, and are so long, they may bounce around before being absorbed by foods, resulting in hot and cold spots.
Of course, in recent decades, companies have tried to solve this problem by having a rotating tray in their microwave ovens, turning the food while it cooks.
One concern as old as microwave ovens themselves is the idea that microwaves may be leaking out from the appliance and filling the kitchen with radiation. The appliance may mostly be lined with metal, but what about that glass door that opens?
“If you look in the front of the microwave, there’s a glass door so that I can see into it, but if you look carefully, there’s a little screen in that glass door, with little holes in it,” Dr. Wolfson said. “Those holes, although they are big enough for us to see through, are small enough that they block microwaves.
“These holes are enormous compared to the wavelength of visible light; however, they are small compared to the wavelength of microwaves; so, basically, they block microwave radiation from coming out.”
Microwaves ovens are the most efficient form of heating food. Before his passing, Robert Schiffmann became a leader in the industry.