资源描述：
《新闻英语视听说(1)听力原文及答案》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。
1、Unit1FoodQualityPartⅠView,ListenandSpeakTaskOne:FoodAdditives(1)Foodadditivesarewidelyusedinmanycountries.However,thediscoveryanumberofyearsagothatthefoodadditiveSudanRedwasharmfultohumanhealthledtoabacklashagainstallfoodadditives.Forexample,themilkwedrinkinthemorninghascalciumaddedtoit
2、;numerousbeveragescontaincalcium,magnesium,potassium,sodiumandotherminerals;storeboughtsaltcontainsiodine,zincandsilica;andpotatochipshaveasmanyas10typesoffoodadditives,suchasspices,ediblepigments,citricacid,flavoradditives,sweeteningagentsandsilica.MSGandcondimentsareconsideredfoodaddi
3、tives.Yeastpowderisalsoafoodadditivetooandisusuallyaddedtosteamedbreads.Evensodiumcarbonateisafoodadditive,too,andisoftenaddedtomakecongee.Tobetterunderstandthefunctionsoffoodadditives,Nature&Sciencedidtwointerestingexperimentsatabakery.Flour,eggs,sugar,saltandsodaarethebasicmaterialsus
4、edinbakingcakes.First,let’smakeacakewithoutanyadditives.Mixingeggyolksandwhitesevenly,wethenaddsomesugarintoit.Whentheeggandsugarare(done)beingmixed,weimmediatelyaddflour,water,sodaandbulkingagentsintothemixtureandrapidlymixthemtomakethebatter.Allthismustbedonewithin10to30secondsafterwh
5、ichthebattermustbeimmediatelyplacedintotheoventobake.Now,let’smakesomecakeswithadditives.Whentheeggsandsugararebeingmixed,weaddsomecakeoiltothemixture.Thecakeoiliscomposedofacidityregulators,antioxidants,vitaminCandsodiumbicarbonate.Itcanmaketheegg-sugarmixturerapidlyinflate.Afterflour,
6、waterandsodaarepouredintotheegg-sugarmixture,thecakeoilcanformcompoundmembraneswithproteinsinthecakebatter.Thiscansignificantlyimprovethestrengthandstabilityofbubblesinthebatterandmakesurethatalloftheingredientsareevenlydistributed.Evenafterthebatterisleftforsometime,thebubbleswillnotdi
7、sappear.Afterthecakesaretakenoutoftheovenwecanseethatthecakesthathadtheoiladdedtothemaremuchnicertolookatandaremoreflexiblethanthosewithouttheadditives.Eventheinsidesofthecakesareremarkablydifferent.Theinternalstructureofthecakewithoutadditivesisunevenandbrittle.Buttheinternals
