The natural food dye revolution.docx
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Thenaturalfooddyerevolution
Thenaturalfooddyerevolution
天然食用色素的成长之路
Asconsumersturntheirbacksonartificialfoodcolorants,foodscientistsarelearninghowtoworkwithnaturalalternatives.SarahHoultoninvestigates
©Shutterstock
It’snearlyadecadesinceastudycarriedoutbyUKscientistsattheUniversityofSouthamptonlinkedahandfulofartificialfoodcolourswithhyperactivityinchildren.Thesixcolours– allurared, carmoisine,ponceau4R, quinolineyellowWS, sunsetyellow and tartrazine –requirethelabeldeclaration‘mayhaveanadverseeffectonactivityandattentioninchildren’inEurope.ConsumerdemandmeansveryfewfoodproductsinEuropenowcontainthem.IntheUK,themostfamiliarareIrn-BruandoriginalLucozade,whichbothstillcontainsunsetyellowandponceau4R.
Thewholesalereformulationofhundredsoffoodproductsthatusedtocontainoneormoreofthesesixsyntheticcolourshasledtoarapidriseintheusageof‘natural’colours.‘Europeisleadingtheconsumerdrivetogetmorenaturals,withcompanieslookingtoreplaceanyartificialcolours,’explainsPersisSubramaniam,headofproductdevelopmentforthefoodinnovationgroupatLeatherheadFoodResearch,UK.‘ItstartedwithSouthampton,butthereisawiderinterestinnaturalproductsingeneralnow,lookingforstorecupboard,back-to-natureingredientsasopposedtohighlyprocessedones.’
TheUSisalongwaybehind.Takethosebrightlycolouredsweets,Skittles.IfyoubuyabagintheUK,theingredientlistingmostlycomprisesnaturalcolours,withtheexceptionofindigocarmineandbrilliantblue,neitherofwhichwasimplicatedintheSouthamptonstudy.Buywhatis,ostensibly,thesamebagofsweetsintheUS(albeitwithgrape-flavouredpurpleonesratherthanthemuchnicerblackcurrant),andthosenaturalcoloursareconspicuousbytheirabsencefromtheproductlabel.Intheirplacearesunsetyellow,tartrazineandallurared.
‘Morethan90%ofallEuropeannewproductlaunchesinthepastfouryearshaveusednaturalcolours,’saysRolandBeck,managingdirectorofthecolorantmanufacturingfirmSensientFoodColorsEuropeinGeesthacht,Germany.‘InNorthAmerica,thefigureisclosertoahalf–andevenlowerifCanadaistakenoutoftheequation.’
十年前英国南安普顿大学(UniversityofSouthampton)的科学家发现儿童最喜欢的人工食品颜色有六种:
诱惑红、淡红、胭脂红、喹啉黄WS、日落黄和酒石黄。
不过如今在英国已经很少见到含有人工色素的食品了。
英国Leatherhead食品研究会的PersisSubramaniam解释道:
“欧洲正引导消费者购买更多天然来源的食品色素,取代人工色素。
这一切始于南安普顿,如今被推广开了。
看看你家的橱柜,就会发现天然食品色素正占据主流。
”
不过美国在这方面却落后了一些。
例如著名的彩色糖果——彩虹糖。
你在英国买一包彩虹糖,会发现配料表中大部分都是天然色素,如槐蓝胭脂红和亮蓝。
但如果你在美国买一包彩虹糖,配料表中取代天然色素的是日落黄、酒石黄和诱惑红。
德国森馨食品色素公司总经理RolandBeck表示:
“过去四年间欧洲90%的产品都使用天然色素,而北美,该比例只有不到一半,如果去掉加拿大,比例会更低。
”(所以美帝也不是啥都好的喂~)
Colourchallenges
Fromachemistrypointofview,thereisnothingbetterthansyntheticcolours,Becksays.‘Theyareincrediblystable,watersolubleandyoucanusetheminanyapplicationatanytemperatureandthecolourshadewillnotchange.’Incontrast,naturalcolourspresentallmanneroftechnicalproblemsforfoodproducers–solubility,pH,temperature,lightandaircanallaffectthecolourandhowitbehaves.
Norbixinisusedtocolourcheesesamongotheruses©Shutterstock
Eachindividualnaturalcolourpigmentproducesitsownformulationchallenge.Forexample,somearewatersolubleandsomeoilsoluble.‘Mostfoodproductsarefairlywater-rich,sotouseanoil-solublepigmentyouneedtoconvertitintoaformthatiscompatiblewithanaqueousenvironment,’Becksays.‘Thisisdonebyemulsification,ordispersionfollowedbystabilisationofthedispersion.’
Choosingtherightemulsifyingsystemforanoil-solublepigmentisimportant.‘Youcan’tuseasucroseesteremulsifiedbeta-caroteneinatypicallowpHbeverageasitisunstablebelowpH4,’Becksays.‘Theemulsionwillbreakdown,givingaringofcolouredoilontheneckofthebottle.Ascolouringingredientformulationsareapplication-specific,manydifferentonesarerequired.Withsunsetyellow,youbuyasinglesolutionthatyoucanuseinanyapplication.Butforbeta-carotene,youwillneedfiveorsixdifferentversions.’
Tocomplicatemattersfurtherforglobalfoodcompanies,thereisnoharmonisedinternationalcolourlegislation,andafoodproductthat’sperfectlyfineinonecountrymaynotbeallowedelsewhere.‘In[EU]legislation,naturalflavoursaredescribed,butthereisnolegaldefinition,’saysOliverLeedam,seniorregulatoryadvisoratLeatherheadFoodResearch.Incontrast,allcoloursareconsideredartificialintheUS,asthecolourofthefoodstuffisbeingchanged.‘There,eachbatchhastobetestedandcertifiedasmeetingthestandards,’headds.VariouscoloursarepermittedinEuropethatarenotintheUS,andviceversa.
Carotenoids
Carotenoidsarefamiliaronfoodingredientlistings,withthelistincludingsubstancessuchas beta-carotene, apocarotenal, lycopene, annatto,paprikaand lutein.Theycandelivershadesfromweakyellowtoareddishcolour,andanythinginbetween.‘Beta-carotenecandeliverweakyellowtoareddish-orangehue,andapocarotenalgivesaverydeeporangecolour,’saysJanHolm-Hansen,managingdirectorofthecarotenoidsproducerAlliedBiotechEurope,inKarlsruhe,Germany.‘Purebeta-caroteneoxidisesrapidlyandisnotwatersoluble–andonlyslightlysolubleinoil.Butviananotechnologyitcanbeencapsulatedandmadesoluble,soitcanbeusedinproductslikejuicesanddairyproducts.Youcanalsoalterthetransratiotohaveanimpactonthecolour.’
Curcuminisusedtocolourmanyyellowsweets©Shutterstock
Physicsisalmostmoreimportantthanchemistrywithcarotenoids,Becksays.‘Theshadeyougetfrombeta-carotenedependsonwhatyoudowithit,’hesays.‘Ifyoumakeatrueemulsion,itisyellow,butifyoumakeadispersionitisorange,andifitiscrystallisedinacertainwaythecolourismorered,likewatermelon.’
Carotenoidswilloftenbeproducedsynthetically,orsemi-synthetically,butarethesamemoleculesfoundinnature.‘Somepeoplewillsaythatthismakesthemartificial,butifit’sinthenaturalboxofcolours,itisexactlythesameasinnature,’Holm-Hansensays.
Theyalldecaybyoxidation,losingtheircolour,soincorporatingantioxidantingredientsisthekeytostabilityandagoodshelf-lifeinthewarehouse,duringprocessingandovertimeonthesupermarketshelf.Thisiscommonlydonewith ascorbicacid, ascorbylpalmitate or tocopherol.
Temperature,pH,airandlightarealsoimportant.‘Foodproductionoftenincludesheattreatmenttocontrolbacteria,whichcanaffectthecolour,’Holm-Hansensays.‘Transparentpackagingmakesthemsubjecttodaylight,soforgoodshelf-lifethecarotenoidmustbemademorestabletolight.WeprotectthemoleculesbyencapsulatingtheminastarchorgumArabic.’
Anothercarotenoidingredient,oleoresinpaprika,iscommonlysuppliedonacarriersuchassalt,andthecolourmightlastonlyfourtosixweeks,saysCarolLocey,naturalcoloursproductdirectoratKalamazoo,US-basedKalsec.Thisnaturalfoodadditivescompanyhasmanagedtoformulateapaprikathatretainsitscolourfortwoorthreeyears.‘Wehavetoselectthebestlotofmaterialtoextract,andthencombineitwithnaturalantioxidantssuchasrosemaryextracttoenhanceitsstability.’
Orange-redannattoisderivedfromtheseedsoftheSouthAmericanachiotetree, Bixaorellana.Themaincolouredcomponentistheoil-solublecarotenoid bixin,Loceysays,whichhasacarboxylicacidgroupatoneendoftheconjugatedchain,andamethylesterattheother. Norbixin isthede-esterifieddiacid,whichiswatersoluble.It’sinwidespreaduseindairyproductssuchascheddar,colbyandredleicestercheeses,whereithasbeenusedforcenturiestoimpartacharacteristicorangecolour.
Betanin,derivedfrombeetroot,isidealforcolouringstrawberryicecream©Shutterstock
Canthaxanthin,meanwhile,producesabrightdeepredcolourand,whileitispermittedintheUS,that’snotthecaseinEurope.IthasanE-number,buttheonlypermittedfooduseisthestrasbourgsausage.Therestrictionarisesfromahealthscareinthelate1980s,whenpeopletakingcanthaxanthincapsulesasasun-tanningaiddevelopedreversibledepositsofcanthaxanthincrystalsintheirretinas.Clearlytheamounttheyhadtakenwasordersofmagnitudegreaterthanwouldeverbeconsumedasafoodcolorant,buttheresultingEUreviewledtoitsalmosttotalban.
类胡萝卜素是食用色素清单上的常客,包括β-胡萝卜素、番茄红素、胭脂树橙、辣椒红素和叶黄素。
它们可以调配出淡黄到橙红间的任何颜色。
β-胡萝卜素能给食物带来很深的橙黄色,不过纯β-胡萝卜素在空气中很容易氧化,不溶于水,脂溶性也很差,幸好有纳米技术能使它形成囊泡,易于在水中分散,因此β-胡萝卜素可以用于果汁和奶制品中。
橙红色的胭脂树橙提取自南美的胭脂树(一种红木属植物)的种子。
主要的色素成分是脂溶性的胭脂素。
而降胭脂素则是一种脱脂后的二酸,水溶性较好。
它作为标志性的橙色,广泛用于切达干酪、科尔比氏干酪和红莱斯特奶酪中,已经长达几个世纪。
在类胡萝卜素的使用上物理比化学管用。
处理方式不同,得到的结果也不同。
如果充分乳化,β-胡萝卜素会呈现黄色;如果只是简单溶解,它是橙色的;β-胡萝卜素的结晶物则是类似于西瓜的红色。
类胡萝卜素的来源大多是合成或半合成,分子式与天然来源相同,因而可以保证功能上相同。
由于类胡萝卜素都很容易氧化褪色,为了使食品更易于保存,它常常与抗氧化剂联用,例如常见的抗坏血酸、抗坏血酸棕榈酸酯和维生素E。
温度和光线也很重要。
食品加工时常常需要高温灭菌,这会影响色素的颜色。
透明的包装袋又使色素暴露于阳光下。
为了延长保质期,类胡萝卜素必须被保护好,常用的方式就是用淀粉或阿拉伯树胶裹住色素分子。
另一种常见的类胡萝卜素是辣椒红素,它的颜色通常只能维持4到6周。
为了延长其保存寿命,Kalamazoo的一家食品添加剂公司开发了一种新技术,使辣椒红素能维持两三年不变色。
这项技术的关键在于严格把控原料质量,以及用迷迭香提取物作为抗氧化剂与色素联用,使其保持稳定。
角黄素带有鲜艳的深红色,它在美国使用是合法的,但欧洲却禁止使用。
不过也有例外,它特许在斯特拉斯堡香肠中使用。
其在欧洲的禁令来自于一起20世纪80年代晚期的健康事故。
当时人们用角黄素作为日光浴佐剂(不懂老外的审美,增黑剂……),结果发现会在视网膜产生角黄素晶体沉淀(可逆)。
显然,这些人的使用量远远高于正常食品中的使用量,不过欧洲还是严格禁止了角黄素的使用。
(食品厂心里苦,这个锅不想背啊)
Water-solublepigments
Thelargestgroupofwater-solublepigmentsistheanthocyanins,whosecolourtendstochangewithpH.‘They’rebasicallyindicators,’Becksays.‘AnanthocyanincanbeanywherefromveryredtoapurpletoblueishatneutralpH,andifyouincreasethepHfurtheritwillgogreenorbrown,andultimatelycolourless.ThispHsensitivitymakesfoodapplicationsarealchallenge.’
Thisisoneofthebi