On food and cooking the science and lore of the kitchen ( PDFDrive ) 1471

water.
Visibleandultravioletlightiscapableof
alteringtheorbitsofelectronsboundin
molecules,andsocaninitiatechemical
reactionsthatcausedamagetopigments
andfatsandthedevelopmentofstale,
rancidflavors.Visibleandultraviolet
raysfromthesuncanruintheflavorof
milkandbeer,andultravioletrayscan
burnourskin,damageourDNA,and
causecancer.
Xandgammarayspenetratematterand
ionizeit,orstripelectronsfromits
molecules.Alongwithcontrolledbeams
ofcertainsubatomicparticles,they
damageDNAandkillmicrobes,andare
usedto“cold-pasteurize”andsterilize
somefoods.
Useful Heat Radiation Is Generated by
High Temperatures Because all molecules
are vibrating to some extent, everything


around us is emitting at least some infrared
radiation all the time. The hotter an object
gets, the more energy it radiates in higher
regionsofthespectrum.Soitisthatglowing
metalishotterthanmetalthatdoesnotradiate
visible light, and that yellow-hot metal is
hotterthanred-hot.Itturnsoutthattherateof
infrared radiation is relatively low below

about 1,800ºF/980ºC, or the point at which
objectsbegintoglowvisiblyred.Cookingby
radiationisthusaslowprocessexceptatvery
high
cooking
temperatures,
those
characteristic of grilling and broiling near
glowing coals, electrical elements, or gas
flames. At typical baking and frying
temperatures,conductionandconvectiontend
tobemoresignificantthaninfraredradiation.
But as the oven temperature goes up, the
proportionofheatcontributedbytheradiating
oven walls goes up with it. The cook can
control this contribution by moving the food
close to the walls or ceiling to increase it, or