On food and cooking the science and lore of the kitchen ( PDFDrive ) 1285

Frostings,Icings,andGlazes
Frostings, icings, and glazes are sweet
coatings for cakes and other baked goods.
In addition to being tasty and decorative,
they protect the food underneath from
dryingout.Thesepreparationsbeganinthe
17th century as plain syrup glazes, and
gradually evolved into more elaborate
forms. Today, glazes are glossy, thin,
densecoatingsmadewithacombinationof
powdered sugar, a small amount of water,
corn syrup, and sometimes fat (butter,
cream).Thecornsyrupandfatpreventthe
sugarfromformingcoarsecrystals,andthe
corn syrup provides a moisture-attracting
liquidphasetofillthespacebetweensugar
particles and create a smooth, glass-like
surface. A warm fondant (around
100ºF/38ºC)pouredoverthecakeorpastry
producesasimilareffect.Simplefrostings
aremadebywhippingsugarandairintoa
solid fat — butter, cream cheese, or


vegetable shortening — to make a sweet,
creamy, light mass. The sugar particles
must be small enough not to make the
frosting seem grainy, so fine grades of
powdered sugar are the usual choice.
Cooked frostings and icings include eggs
or flour and owe their body in part to the

egg proteins or flour starch. Because the
sugar dissolves during the cooking, its
particlesizeisunimportant.
CookingtheSyrupRaisestheSugar
ConcentrationAsasugarsolutionboils,
watermoleculesevaporatefromtheliquid
phaseintotheair,whilethesugarmolecules
staybehind.Thesugarmoleculestherefore
accountforalargerandlargerproportionof
allthemoleculesinthesolution.Soasit
boils,thesyrupgetsmoreandmore
concentrated:andthisinturncausesits
boilingpointtocontinuetorise.Inorderto
makeasyrupofagivensugarconcentration,
allthecandymakerhastodoisheatamixture