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The Physics and Chemistry Of Baking
Transcript of The Physics and Chemistry Of Baking
infrared light waves cause atoms within cake to interact with other atoms
every atom physically bonded to neighbor, heat energy supplied - atom vibrates
The Baking Tin
Circular - even spread of heat
Dull and rough metal - absorbs and conducts heat (reduce cooking time by 20%)
Non-stick tins covered in polytetrafluoroethylene (so dense nothing can bind to)
air inside heated by
(spontaneous transfer of heat from region of higher to lower temperature)
air then circulated by
due to different densities between hot and cold air - pre-set temperature
more vibrations of atom - more bonds shake - passed onto nearby atoms - energy then passes throughout mixture and overall temperature of cake increases - gas cells (beaten/whisked) expand and chemical rising agent (baking powder) release carbon dioxide
bubbles of gas create gaps in mixture - cake expands to rise
Wendy Zhou and Natalie Stamatiadis
cake mixture set into permanent shape by starch gelatinization (starch dissolves as exposed to heat and water)
only occurs in areas where moisture has been driven from cake (cake temperature must be at least 100 degrees Celsius, BP of water)
occurs first on outside and surface of cake as they have more contact with heat than inside
bubbles whisked in earlier in process expanded under heat - retract as they cool
flour prevents structure from collapsing (sunken and soggy cake - not enough flour for amount of liquid in mixture)
AP Physics B
heat contained within oven by heat-proof material designed to reflect infrared waves created by hot air
flour, egg, and milk protein coagulate (starch and protein molecules from egg and/or milk line up along walls of gas cells)
as protein chains form, giving structure, water squeezed from between proteins and absorbed by starch granules
too high temperature - outside may burn before whole mixture has set
too low temperature - mixture solidifies too slowly, allowing gas cells to expand too far and begin to fuse
when outside begins to cook and get hard inside no longer able to expand
if outer layer not strong enough to contain pressure - cake surface will split to release internal pressure