The natural food dye revolution.docx

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