What's wrong with synthetic colorants?

In 2007, Pro­fes­sor James Steven­son from Southamp­ton Uni­ver­si­ty pub­lished a pa­per claim­ing that there was a link be­tween the con­sump­tion of ar­ti­fi­cial food col­orants and hy­per­ac­tiv­i­ty among chil­dren.

Steven­son’s pa­per dis­cussed sev­er­al syn­thet­ic food col­orants with the let­ter “E”: E102, E104, E110, E122, E124 и E129. Al­though the British Food Stan­dards Agen­cy, which fi­nanced Steven­son’s re­search, ad­mit­ted that there were no strict sci­en­tif­ic facts to back up these claims, it called on lo­cal man­u­fac­tur­ers to stop us­ing the food col­orants men­tioned in the pa­per. Eu­ro­pean so­ci­ety en­thu­si­as­ti­cal­ly latched on to these ideas, and nu­mer­ous protests were held in the EU. Alarmed par­ents de­mand­ed for syn­thet­ic food col­orants to be re­moved from food and drinks.

Chang­ing moods

Man­u­fac­tur­ers had to change the com­po­si­tion of hun­dreds of prod­ucts. Syn­thet­ic food col­orants (not just the six in Steven­son’s pa­per, but oth­ers as well) were re­placed by col­orants ex­tract­ed from nat­u­ral sources. Around 90% of food prod­ucts that have ap­peared on the Eu­ro­pean mar­ket in re­cent years only con­tain nat­u­ral pig­ments.

It’s not cer­tain that Eu­ro­pean chil­dren im­me­di­ate­ly be­came health­i­er af­ter these changes. But chemists and tech­ni­cians were un­doubt­ed­ly giv­en a lot more work to do.

Chang­ing col­ors

Man­u­fac­tur­ers love “chem­istry”

From the stand­point of a chemist and tech­ni­cian, syn­thet­ic food col­orants are won­der­ful. They are durable, sol­u­ble in wa­ter, can be used in any recipe, and most of them do not change their col­or in ther­mal pro­cess­ing. Nat­u­ral food col­orants are much more com­plex: their ap­pear­ance is af­fect­ed by acid­i­ty, tem­per­a­ture, light and even con­tact with oxy­gen. Worst of all, far from all food col­or­ings of nat­u­ral ori­gin dis­solve well in wa­ter.

Yel­low and red

Nat­u­ral pig­ments are a very capri­cious bunch gen­er­al­ly. For ex­am­ple, take beta-carotene, which re­placed the syn­thet­ic food col­orant “sun­set” (E110). For E110, food tech­ni­cians could use one uni­ver­sal so­lu­tion, but for beta-carotene there are six ver­sions, de­pend­ing on what needs to be turned yel­low – juice, can­dy or some­thing else. Beta-carotene dis­solves in fats, and some­times it has to be used in prod­ucts that con­tain a large amount of wa­ter. As fats do not mix with wa­ter, and the prod­uct must be col­ored even­ly, sta­bi­liz­ers must be added – com­plex es­ters of su­crose. But with these sta­bi­liz­ers, the mix­ture is only sta­ble in a strong­ly acidic medi­um, and if the pH is greater than 4, it sep­a­rates.

Man­u­fac­tur­ers are saved by nan­otech­nol­o­gy. To make beta-carotene and sev­er­al sim­i­lar com­pounds ca­pa­ble of col­or­ing juices or dairy prod­ucts, they are placed in hol­low nanopar­ti­cles. In them, the col­or­ing can spread through­out the prod­uct. But even with this method, dif­fer­ent nano-cap­sules must be de­vel­oped for dif­fer­ent types of prod­ucts.

Af­ter ox­i­da­tion, carotenoids (the group that beta-carotene be­longs to) lose their col­or. So to keep prod­ucts on su­per­mar­ket shelves look­ing fresh, anti-ox­i­dants must be added to them. Usu­al­ly, ascor­bic acid and its de­riv­a­tives are used as anti-ox­i­dants, or to­co­pherol (food ad­di­tives E306-E309). And if a prod­uct col­ored by carotenoids is placed in a trans­par­ent plas­tic con­tain­er, in or­der to pro­tect the pig­ments which break down in light, it must be en­cap­su­lat­ed in starch or gum Ara­bic – a resin se­cret­ed by var­i­ous species of aca­cia tree.

Carotenoid col­orants are of­ten made syn­thet­i­cal­ly, and not from nat­u­ral sources. And al­though beta-carotenes ex­tract­ed from car­rots and those man­u­fac­tured in the lab­o­ra­to­ry are ab­so­lute­ly iden­ti­cal, par­tic­u­lar­ly sus­pi­cious peo­ple con­sid­er these carotenoids to be ar­ti­fi­cial and un­ac­cept­able. Wa­ter-sol­u­ble nat­u­ral col­orants also ex­ist. They are an­tho­cyanins. They are made from an­tho­cyans (isn’t that a sur­prise?) – sub­stances which in na­ture of­ten de­ter­mine the col­or of the petals of flow­ers, fruits and au­tumn leaves. But there are also cer­tain dif­fi­cul­ties with an­tho­cyanins: their col­or de­pends on the pH lev­el. These com­pounds are in fact in­di­ca­tors of the ba­sic medi­um: in a neu­tral medi­um an­tho­cyanins, de­pend­ing on their struc­ture, may turn red, pur­ple or blue, at a high pH lev­el they be­come green or brown, and in an acid medi­um their col­or van­ish­es.

An­oth­er draw­back of an­tho­cyanins is their sen­si­tiv­i­ty to light. And here, un­like carotenoids, ascor­bic acid does not help, be­cause it de­col­orizes an­tho­cyanins it­self.

An­oth­er nat­u­ral wa­ter-sol­u­ble pig­ment, cur­cum­in, is made from turmer­ic root. The bright lemon-yel­low col­or of cur­cum­in quick­ly turns dull in the light and breaks down in drinks, es­pe­cial­ly un­der the joint im­pact of light and wa­ter, so it can’t be used to col­or fizzy drinks.

Even when chemists man­age to col­or a prod­uct with nat­u­ral col­orants, not all mod­ern con­sumers are al­ways hap­py with the in­gre­di­ents. For ex­am­ple, many man­u­fac­tur­ers have stopped us­ing one of the best nat­u­ral col­orants, carmine (E120), which gives an in­tense and durable red col­or. Carmine is a col­orant of pure­ly nat­u­ral ori­gin, but it is made from the fe­male scale in­sects Dacty­lop­ius coc­cus. This is why veg­e­tar­i­ans will not eat food con­tain­ing E120. Ad­di­tion­al­ly, it is pro­hib­it­ed in ha­lal and kosher food. When pos­si­ble, carmine is re­placed by an­tho­cyanins, but oth­er­wise be­tanin (E162) is used, a pig­ment that is found in beet­root. Some types of beet­root are grown spe­cial­ly for mak­ing be­tanin.

The main draw­back of be­tanin is that when heat­ed, it changes its col­or from red to brown, and like most nat­u­ral col­orants, it breaks down in light. This doesn’t look very ap­pe­tiz­ing, you must agree. An ide­al prod­uct for be­tanin is ice cream, which is stored in cold and dark con­di­tions. In­ci­den­tal­ly, this is why straw­ber­ry ice cream con­tains a lit­tle beet­root. But with food that must be heat­ed, some­times the en­tire man­u­fac­tur­ing tech­nol­o­gy must be changed, with col­orants added to the fin­ished prod­uct.

Green and blue

Even more prob­lems arise when food needs to be col­ored green or blue. This is be­cause there are far few­er nat­u­ral green or blue col­orants than or­ange and red pig­ments that pre­serve their col­ors dur­ing and af­ter cook­ing.

Usu­al­ly, chloro­phyll is used as a green col­orant, the same chem­i­cal that makes leaves green. Or a de­riv­a­tive of it, cop­per chloro­phyllin. You can get a light green col­or by mix­ing any of these sub­stances with cur­cum­in. How­ev­er, chloro­phyll and cop­per chloro­phyllin lose their col­or in an acid medi­um, but un­til the ex­piry date of most prod­ucts, these pig­ments keep their col­or. Not with­out the help of sta­bi­liz­ers, of course.

The only cur­rent­ly avail­able blue pig­ment of nat­u­ral ori­gin is the col­ored pro­tein phy­co­cyanin, which is se­cret­ed by cyanobac­te­ria (blue-green al­gae). But as this is a pro­tein, it can only be used in prod­ucts with a neu­tral pH, for ex­am­ple in hard can­dies.

In Eu­rope chloro­phyll de­riv­a­tives and phy­co­cyanin are per­mit­ted, but in the USA chloro­phyll and cop­per chloro­phyllin are pro­hib­it­ed. This means that Amer­i­can food man­u­fac­tur­ers have to make green food col­orants by mix­ing phy­co­cyanin with cur­cum­in. In­ci­den­tal­ly, even though cur­cum­in is a pig­ment of nat­u­ral ori­gin, it ap­pears on the list of in­gre­di­ents as col­orant E100. So the let­ter E with num­bers af­ter it does not al­ways mean that the prod­uct con­tains any­thing syn­thet­ic.

The con­c­umer is un­pleased

Keep­ing capri­cious cus­tomers hap­py

When man­u­fac­tur­ers put out a new line of prod­ucts con­tain­ing nat­u­ral col­orants on the mar­ket, ev­ery­thing goes quite smooth­ly: con­sumers don’t have pre­con­cep­tions about the col­or of juice or can­dy, as long as it tastes good. But it’s an­oth­er mat­ter with prod­ucts that have been on the mar­ket for a long time, where syn­thet­ic col­orants were re­placed with nat­u­ral ones. In Eu­rope, and es­pe­cial­ly in the USA, con­sumers are used to the bright col­ors of syn­thet­ic food col­or­ings. Peo­ple are not par­tic­u­lar­ly hap­py when fa­mil­iar prod­ucts turn a dull col­or when nat­u­ral pig­ments are used. An­oth­er im­por­tant fac­tor is that these re­place­ments usu­al­ly make the prod­uct more ex­pen­sive. The only method that helps to at­tract con­sumers is ad­ver­tis­ing cam­paigns that ex­plain that al­though their fa­vorite or­ange can­dy doesn’t look as bright as it used to, now it is col­ored by nat­u­ral car­rots, and not by some syn­thet­ic E122. Al­though this ap­proach only in­creas­es the ir­ra­tional fear of ev­ery­thing chem­i­cal. The only undis­put­ed ad­van­tage of this para­noia is that new stud­ies and ex­per­i­ments are car­ried out for the ben­e­fit of hu­man­i­ty.

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