The natural food dye revolution.docx

1、The natural food dye revolutionThe natural food dye revolution天然食用色素的成长之路As consumers turn their backs on artificial food colorants, food scientists are learning how to work with natural alternatives. Sarah Houlton investigates ShutterstockIts nearly a decade since a study carried out by UK scientis

2、ts at the University of Southampton linked a handful of artificial food colours with hyperactivity in children. The six colours allura red,carmoisine,ponceau 4R,quinoline yellow WS,sunset yellowandtartrazine require the label declaration may have an adverse effect on activity and attention in childr

3、en in Europe. Consumer demand means very few food products in Europe now contain them. In the UK, the most familiar are Irn-Bru and original Lucozade, which both still contain sunset yellow and ponceau 4R.The wholesale reformulation of hundreds of food products that used to contain one or more of th

4、ese six synthetic colours has led to a rapid rise in the usage of natural colours. Europe is leading the consumer drive to get more naturals, with companies looking to replace any artificial colours, explains Persis Subramaniam, head of product development for the food innovation group at Leatherhea

5、d Food Research, UK. It started with Southampton, but there is a wider interest in natural products in general now, looking for store cupboard, back-to-nature ingredients as opposed to highly processed ones.The US is a long way behind. Take those brightly coloured sweets, Skittles. If you buy a bag

6、in the UK, the ingredient listing mostly comprises natural colours, with the exception of indigo carmine and brilliant blue, neither of which was implicated in the Southampton study. Buy what is, ostensibly, the same bag of sweets in the US (albeit with grape-flavoured purple ones rather than the mu

7、ch nicer blackcurrant), and those natural colours are conspicuous by their absence from the product label. In their place are sunset yellow, tartrazine and allura red.More than 90% of all European new product launches in the past four years have used natural colours, says Roland Beck, managing direc

8、tor of the colorant manufacturing firm Sensient Food Colors Europe in Geesthacht, Germany. In North America, the figure is closer to a half and even lower if Canada is taken out of the equation.十年前英国南安普顿大学（University of Southampton）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

9、品了。英国Leatherhead食品研究会的Persis Subramaniam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Roland Beck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。”（

10、所以美帝也不是啥都好的喂）Colour challengesFrom a chemistry point of view, there is nothing better than synthetic colours, Beck says. They are incredibly stable, water soluble and you can use them in any application at any temperature and the colour shade will not change. In contrast, natural colours present all

11、 manner of technical problems for food producers solubility, pH, temperature, light and air can all affect the colour and how it behaves.Norbixin is used to colour cheeses among other uses ShutterstockEach individual natural colour pigment produces its own formulation challenge. For example, some ar

12、e water soluble and some oil soluble. Most food products are fairly water-rich, so to use an oil-soluble pigment you need to convert it into a form that is compatible with an aqueous environment, Beck says. This is done by emulsification, or dispersion followed by stabilisation of the dispersion.Cho

13、osing the right emulsifying system for an oil-soluble pigment is important. You cant use a sucrose ester emulsified beta-carotene in a typical low pH beverage as it is unstable below pH 4, Beck says. The emulsion will break down, giving a ring of coloured oil on the neck of the bottle. As colouring

14、ingredient formulations are application-specific, many different ones are required. With sunset yellow, you buy a single solution that you can use in any application. But for beta-carotene, you will need five or six different versions.To complicate matters further for global food companies, there is

15、 no harmonised international colour legislation, and a food product thats perfectly fine in one country may not be allowed elsewhere. In EU legislation, natural flavours are described, but there is no legal definition, says Oliver Leedam, senior regulatory advisor at Leatherhead Food Research. In co

16、ntrast, all colours are considered artificial in the US, as the colour of the foodstuff is being changed. There, each batch has to be tested and certified as meeting the standards, he adds. Various colours are permitted in Europe that are not in the US, and vice versa.CarotenoidsCarotenoids are fami

17、liar on food ingredient listings, with the list including substances such asbeta-carotene,apocarotenal,lycopene,annatto, paprika andlutein. They can deliver shades from weak yellow to a reddish colour, and anything in between. Beta-carotene can deliver weak yellow to a reddish-orange hue, and apocar

18、otenal gives a very deep orange colour, says Jan Holm-Hansen, managing director of the carotenoids producer Allied Biotech Europe, in Karlsruhe, Germany. Pure beta-carotene oxidises rapidly and is not water soluble and only slightly soluble in oil. But via nanotechnology it can be encapsulated and m

19、ade soluble, so it can be used in products like juices and dairy products. You can also alter the trans ratio to have an impact on the colour.Curcumin is used to colour many yellow sweets ShutterstockPhysics is almost more important than chemistry with carotenoids, Beck says. The shade you get from

20、beta-carotene depends on what you do with it, he says. If you make a true emulsion, it is yellow, but if you make a dispersion it is orange, and if it is crystallised in a certain way the colour is more red, like watermelon.Carotenoids will often be produced synthetically, or semi-synthetically, but

21、 are the same molecules found in nature. Some people will say that this makes them artificial, but if its in the natural box of colours, it is exactly the same as in nature, Holm-Hansen says.They all decay by oxidation, losing their colour, so incorporating antioxidant ingredients is the key to stab

22、ility and a good shelf-life in the warehouse, during processing and over time on the supermarket shelf. This is commonly done withascorbic acid,ascorbyl palmitateortocopherol.Temperature, pH, air and light are also important. Food production often includes heat treatment to control bacteria, which c

23、an affect the colour, Holm-Hansen says. Transparent packaging makes them subject to daylight, so for good shelf-life the carotenoid must be made more stable to light. We protect the molecules by encapsulating them in a starch or gum Arabic.Another carotenoid ingredient, oleoresin paprika, is commonl

24、y supplied on a carrier such as salt, and the colour might last only four to six weeks, says Carol Locey, natural colours product director at Kalamazoo, US-based Kalsec. This natural food additives company has managed to formulate a paprika that retains its colour for two or three years. We have to

25、select the best lot of material to extract, and then combine it with natural antioxidants such as rosemary extract to enhance its stability.Orange-red annatto is derived from the seeds of the South American achiote tree,Bixa orellana. The main coloured component is the oil-soluble carotenoidbixin, L

26、ocey says, which has a carboxylic acid group at one end of the conjugated chain, and a methyl ester at the other.Norbixinis the de-esterified diacid, which is water soluble. Its in widespread use in dairy products such as cheddar, colby and red leicester cheeses, where it has been used for centuries

27、 to impart a characteristic orange colour.Betanin, derived from beetroot, is ideal for colouring strawberry ice cream ShutterstockCanthaxanthin, meanwhile, produces a bright deep red colour and, while it is permitted in the US, thats not the case in Europe. It has an E-number, but the only permitted

28、 food use is the strasbourg sausage. The restriction arises from a health scare in the late 1980s, when people taking canthaxanthin capsules as a sun-tanning aid developed reversible deposits of canthaxanthin crystals in their retinas. Clearly the amount they had taken was orders of magnitude greate

29、r than would ever be consumed as a food colorant, but the resulting EU review led to its almost total ban.类胡萝卜素是食用色素清单上的常客，包括-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。-胡萝卜素能给食物带来很深的橙黄色，不过纯-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-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

30、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，-胡萝卜素会呈现黄色；如果只是简单溶解，它是橙色的；-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

31、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

32、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-soluble pigmentsThe largest group of water-soluble pigments is the anthocyanins, whose colour tends to change with pH. Theyre basically indicators, Beck says. An anthocyanin can be anywhere from very red to a purple to blueish at neutral pH, and if you increase the pH further it will go green or brown, and ultimately colourless. This pH sensitivity makes food applications a real challenge.This is one of the bi