On food and cooking the science and lore of the kitchen ( PDFDrive ) 203

contributemuchtotherawfoam.Butitis
sensitivetoheat,whichcausesittounfoldand
coagulate.Sowhentherawfoamiscooked,
ovalbuminmorethandoublestheamountof
solidproteinreinforcementinthebubble
walls.Atthesametime,muchofthefree
waterinthefoamevaporates.Heatthus
allowsthecooktotransformatransientsemiliquidfoamintoapermanentsolidone.
HowProteinsDestabilizeFoams

Theverysameforcesthatmakeeggfoams
alsobreakeggfoams.Oftenjustasthefoam
isreachingitsoptimumtexture,itwillget
grainy,losevolume,andseparateintoadry
frothandarunnyliquid.Astheproteinsbond
toeachothertosupportthefoam,they
embraceeachothertootightly,andsqueeze
outthewatertheyhadheldbetweenthem.
Thereareseveraldifferentkindsofbondsby
whichthelong,unfoldingeggproteinsare


joinedtoeachotherinareinforcingnetwork:
bondsbetweenpositivelyandnegatively
chargedpartsofmolecules,betweenwaterlikeparts,betweenfat-likeparts,andbetween
sulfurgroups.Theproteinnetworkbeginsto
collapsewhentoomanyofthesebonds
accumulateandtheproteinsclustertogether
tootightly.Fortunately,therearesimpleways
forthecooktolimittheaccumulationof
bondsandpreventthecollapseofalbumen

foams.
Blocking Sulfur Bonds with Copper
Bowls…Longbeforeanyoneknewaboutegg
proteins or their chemical bonds, cooks had
comeupwithawayofcontrollingthem.The
Frenchtraditionhaslongspecifiedtheuseof
copper utensils for making egg foams. One
early trace of this tradition is a 1771
illustration in the FrenchEncyclopédie that
showsaboyinapastrykitchenworkingwith
astrawwhiskandwhattheaccompanyingkey