On food and cooking the science and lore of the kitchen ( PDFDrive ) 1474

and40,000cyclespersecond).Thecurrent
causesthecoiltogenerateamagneticfield
that extends some distance from the coil,
andthatalternatesatthesamerate.Ifapot
made from a magnetic material — cast
iron, steel, stainless steel of the proper
crystalstructure(ferritic)—isplacednear
thecoil,thenthealternatingmagneticfield
induces an alternating electrical current in
thepot.Thatis,itcauseselectronstomove
in the pot, and that movement rapidly
generatesheat.
Induction heating has two notable
advantages over burners and radiant
elements. Like microwave heating, it’s
moreefficient,becausealltheenergygoes
into the object to be heated, not into the
surrounding air. And only the pot and its
contentsgetveryhot.Theceramicsurface
above the induction coil is heated only
indirectlybythepot,becauseitselectrons
aren’t free to be moved by the magnetic


field.
Baking:AirConvectionandRadiation

Whenwebakeafood,wesurrounditwitha
hotenclosure,theoven,andrelyona
combinationofradiationfromthewallsand
hot-airconvectiontoheatthefood.Baking

easilydehydratesthesurfaceoffoods,andso
willbrownthemwellprovidedtheoven
temperatureishighenough.Typicalbaking
temperaturesarewellabovetheboilingpoint,
from300to500ºF/150–250ºC),andyetbaking
isnowherenearasefficientameansofheat
transferasisboiling.Apotatocanbeboiled
inlesstimethanittakestobebakedata
muchhottertemperature.Thisissobecause
neitherradiationnorairconvectionat500ºF
transfersheatveryrapidlytofood.Ovenairis
lessthanathousandthasdenseaswater,so
thecollisionsbetweenhotmoleculesandfood
aremuchlessfrequentintheoventhaninthe