Chemistry Reference
In-Depth Information
8.9.12 Cookies
Cookies,likecakes,arechemicallyleavenedwithbakingsodaorbakingpowder.Cookies,how-
ever,havemoresugarandshorteningandlesswaterproportionately.Incookies,sugarintroduces
airintothebatterduringthecreamingprocess.Approximatelyhalfthesugarremainsundissolved
attheendofmixing.Whenthecookiedoughenterstheoven,thetemperaturecausestheshortening
tomeltandthedoughtobecomemoreluid.Theundissolvedsugardissolvesasthetemperature
increasesandthesugarsolutionincreasesinvolume.Thisleadstoamoreluiddough,allowingthe
cookiestospreadduringbaking(Godshall1990;Ponte1990).
Sugaralsoservesasalavorant,caramelizingwhilethecookiesarebaked.
Nutritivesweetenersaffectcookietexture;someproducehard,crispyproductsandotherssoft,
chewyproducts.Sweetenersalsoinluencethespread,surfacecracking,andbrowncolorforma-
tionoftheinalproduct.Thetypicalnutritivesweetenercontentofcookiesis20%-40%;whereas,
concentrationofhigh-intensitysweetenersincookiesis0.5%-2%.
Bulkingagentsareaddedinthecreamingstagetoreducelumpinginthedoughanddecrease
thepossibilityofagummytexture(DarteyandBriggs1987).However,mostbulkingagentsbind
water, creating problems with cookies that need to be crispy and hard. This is not the case with
soft,chewycookiesandbulkingagents,suchaspolydextrose,cellulosepowders,ibers,gums,and
maltodextrins, are used with good results (Khan 1993). For a hard, crispy texture, some sucrose
must be present in order for recrystallization to take place, resulting in the formation of a glass
structure.Sugaralcoholswithlowhygroscopicity(mannitol,isomalt,andlactitol)aidinachieving
crispness(Altschul1993).
Reduction in spread is one of the most notable results of replacing nutritive sweeteners.
Polydextroseincreasesthespreadofcertaincookieformulations;whereas,itdecreasesdoughcohe-
siveness.Sugaralcoholscanbeused,andfatcontentcanbeincreasedtoimprovethespread.
Cracking on the cookie surface results from recrystallization of sucrose and surface drying.
Reducing the moisture level can improve cracking but can also reduce dough-handling quality,
inhibitspread,andresultinadry,brittleproduct(Nelson2000a,b).
8.10 CaNDY prOCeSSING
Hardcandyformulationscomprisesugar,aglucosesyrup(usedata20%-50%rangeinthefor-
mulawithaDEof38-48toenhancelavorsandmaintaingoodmoisturecontrol),color,andlavor.
Incandymaking,sugarisirstdissolvedinwateratroomtemperaturetothepointatwhichno
moresugarwilldissolve(sugartowaterratio1:1/2).Theresultisasaturatedsolution.Thissatu-
ratedsolutionisplacedoverheatandstirredcontinuously,allowingmoresugartodissolveintothe
solution.Thesolutionisthenheatedtoboiling(152°C-168°C),creatingasupersaturatedsolution.
The supersaturated sugar solution is then heated to above BP, forcing more and more water to
evaporateandthesolutiontobecomeevenmoreconcentrated(Gates1981).Ifcrystalsdonotcom-
pletelydissolve,theyactassitesfornucleationandcrystalgrowth.Ifviscosityofasyrupistoolow,
crystallizationoccursandcanbeincreasedbytheadditionofalow-DEglucose-containingsyrup
(Alexander1998).
The three methods of boiling hard candies include open pan, vacuum, and continuous ilm
or scraped-surface heat exchanger. The ratio of sucrose to glucose in open-pan boiling is 70:30;
whereas,intheothertwo,itisapproximately60:40.Vacuumboilersareusedinclearorcolorless
candiesbecausetheydecreaseboilingtemperatureandproducelessbrowningoroffcolors.High-
maltosesyrupsareusedinprocessesrequiringextremelyhightemperatures.
Thedegreeofsugarconcentrationofthesupersaturatedsolutioncandeterminethecandy'sinal
consistency.Bymonitoringthestagesofthesupersaturatedsolutionwithacandythermometerand
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