Microwaves Flashcards
What is microwave technology?
Taking advantage of physics of the electromagnetic spectrum
What are microwave waves?
Low range of radio waves
What is visible light in nm
600 nm
Ultraviolet nm
Short nm
X rays and gamma rays
Even shorter nano meters (and are damaging/ penetrating)
What contains infrared radiation?
Oven/ cooking top
Microwaves
High frequency electromagnetic waves of radiant energy
How can we translate wave lengths on electromagnetic spectrum?
Can translate/ relate it to energy
Important characteristic of radio waves/ electromagnetic waves
- wave length and frequency*
What does frequency of waves relate to?
How easily the waves or electromagnetic energy are absorbed or reflected and transmitted
Is infrared heat typically absorbed or transmitted?
Absorbed, think about cooking
Are radio waves typically absorbed or reflected?
Both absorbed and transmitter
What allows us to image bones from x-rays
X-rays are strongly absorbed
Speed of microwaves vs. Conventional cooking
Can cook a product 2 - 10 times faster than conventional infrared heating
How do microwaves heat faster?
Specific heat capacity of foods and their subsittuents
Specific heat capacity
Amount of energy (calories) require to raise a gram of a product by 1 degree C
Heat capacity of water (control)
1 calorie of energy to raise 1 gram of water by 1 degree c
Why do beef, bacon and oil have lower heat capacities?
Decreased caloric value because lipid has lower specific heat
How does water heat products?
Using radio waves relies on water (polar) so it is able to flip flop and vibrate in electromagnetic wave situation. Flipping back and forth heats your product
Why do lipids have a lower heat capacity?
Cooking oil or other lipids have long hydrocarbon molecules which can vibrate and move in your product heating your product
Why so sugars have such a low specific heat (0.3)
Because polar and can hydrogen bond water
Two general frequencies allowed in microwave energy
2450 MHz and 915 MHz (megahertz)
2450 mHz in cm?
12 cm
915 MHz in cm?
33 cm (close to foot)
Difference between 2450 and 915?
2450 greater frequency, shorter wavelength so dont penetrate product all that well. 915 has lower frequency and longer wavelengths which can penetrate a product better
Which is better between 2450 and 915?
Higher frequency is still better to heat smaller products less penetration doesnt matter and still gets heated
Other factor of microwave?
Power output
What is power output?
400-500 watts for smaller 600-700 watts for larger
Lower vs higher power output?
Lower heats products more slowly
Container product is held in and impact
…
Glass, paper, ceramics
Waves on energy pas through and interact with your food
Metal in microwave result
Observe metal arcing, sparking, breaking microwave due to metal spark arcing
Arcing
Concentration of energy which can burn out the magnetron in microwave (creates electromagnetic waves in your oven)
What are microwaves bad at?
Browning
Why are microwaves bad at browning?
Moisture can evaporate and then fall and condense on food item so will not get browning
Heat susceptors?
Coated foil will collect and concentrate heat energy so the kernels will retain heat and pop. Will contribute to more crisping that you otherwise would not have
