Types of red food colouring – A guide on red food colours

Whoever decided to make red velvet cookies with dark cocoa powder must have had some strong bright red coloring. Coloring a dark brown recipe to become red is a lot harder than coloring a simple whitish batter or cookie dough. Real red is only achieved with quite a heap of red food colouring and also one that’s stable enough to resist the heat of baking. Else you’ll still end up with a brownish baked brown velvet cake instead of red.

When making a red velvet cake roll which is supposed to be bright red with a white filling, you’re probably wondering how to make sure it’s that nice colour. You might have also come up with the idea to just use a natural food colouring for this red velvet, not wanting to use an artifical one. Or you are using an artificial one but have no clue where it comes from. If so, look no further, this post will dive into the depths and details of red food colouring to create a brilliant red velvet cake (or cookies).

On red food colouring

When making a red velvet cake you will need to add some sort of food colouring to make that cake bright red. It may sound stable, but without realizing you’re looking for quite a complex colourant. It should first of all be bright red, preferably not to sensitive to the pH (acidity) of your baked good and it should remain red when cooked.

For some colours, this isn’t any issue at all. However, without realizing you might have chosen a colour that does not meet these criteria and instead end up with a non-red red velvet! When discussing all these different colours there’s one main distinction you should understand, the difference between artificial and natural colourants.

On artifical vs natural colours

Roughly, there are two main categories of red food colouring: artificial and natural colours. Artificial colours do not occur in nature, instead, they have been made by humans only. In a lot of cases these colours were actually invented accidentally.

Natural colours however are colours which also occur in nature. These natural colours can either be resourced from nature directly (naturally derived). However, they can also be made by chemists. These nature identical colours do have the same molecular structure though, but aren’t made by, for example, a tomato but instead a chemist.

If the colours are sold they have been approved for use by the food safety authorities. Generally speaking, the artificial colours are very stable and can be used in most recipes. Most natural colours (with the exception of one as we’ll see below) though are highly unstable. Their colour might look perfect in the bottle. Once they’re mixed with your batter or dough or baked in the oven, the colour can change drastically.

Anthocyanins

Anthocyanins are a very prevalent natural food colouring in fruits and vegetables. Examples of sources are red cabbage, red wine and various berries. Generally speaking, you will not be able to buy food colouring made purely from anthocyanins. They aren’t stable enough.

The biggest disadvantage of these molecules is their instability with regards to pH (acidity). At higher pH-values anthocyanins turn a purple/blue colour instead of a bright red. This can be shown very well in red cabbage. If you’re planning on using these it is worthwhile to add some extra acid (e.g. buttermilk, lemon juice) to the batter or dough. The acidity will help the colour remain red.

Also, this colour tends to be a lot weaker than artificial colours. In other words, you might need a lot more of the colour and that can affect your recipe from a consistency but even flavour perspective.

The Ktchen did a series of experiments with pomegranate juice (a source of anthocyanins) to bake a red velvet cake. Unfortunately they weren’t successful. The pomegranate juice wasn’t strong enough, even with the addition of some extra acids.

Azo-dyes

Azo-dyes are artifical food colourants. All azo-dyes have the same molecular structure inside the molecule: a so called ‘azo’ group.An azo-group is a structure of two nitrogen atoms attached to one another with a double bond and both being connected to another part of the molecule (-N=N-). This group is importance with regards to its colour properties.

Azo-dyes can be produced very easily. The starting components are readily available in the chemical industry. Also, the chemical reactions don’t need elevated temperatures and they can be tweaked in such a way that a whole range of colours can be made (as you will see below).

Azo-dyes are water soluble, but will not dissolve in oil or fat. They are very stable and are not affected by pH (acidity) or heat, nor will their colour fade through light or oxygen.

Azorubine

Azorubine (also called carmoisine) is an example of an azo food dye It cannot be found in nature. In Europe it is approved for use in food and has the number E122. This colour made the bright red red velvet cake you see in the photo at the top of this post. The colour didn’t change during baking and was very stable.

Azorubine - red colour e122 - source: wikipedia Fvasconcellos
The molecular structure of azorubine, source: Wikipedia.

Allura red AC

This is another example of an azo dye, permitted in the EU with number E129, in the US it has number 40. Both regions use a different way of naming food colours and have different procedures to allow a new food colour. Allura red AC is one of the most commonly used red colour in the US. It is, just like azorubine, very stable and therefore easy to use. If manufacturers want to switch out allura red AC for a natural food colourant this is often a challenge. Not a lot of other food colourants are as stable.

Others

Lithol rubin BK is another example of a red azo dye (E180), but it is only used for coating cheeses (in Europe at least). Two other red azo-dies are Amaranth (E123) and red 2G (E128). There are less common in foods. Ponceau 4R (E124) can be found in food colourants online.

In this post you’ll only fin red colours. However, within the azo-dye category there are plenty of other completely different colours!

Betalain – Red beet

The molecules responsible for the bright red colour of beetroots are betalain molecules. These are a separate group of natural food colours, in the EU beetroot extract is registered under number E126. Even though betalain is quite stable, it is by far not as stable as the azo-dyes discussed before.

Temperature, the presence of oxygen and light can break down the colour. Therefore, beetroot juice cannot be stored for long without losing colour. That said, certain antioxidants and so-called chelating agents can help to stabilize the colour. Also, betalains are stable over a pretty wide pH-range: 3 – 7. Since most baked goods have a pH-value of 5-7, that won’t be an issue.

There are ways to stabilize the betalain colour. Drying betalains, or incorporating them in a stabilizing environment (e.g. a gelatin gel) will extend the stability thanks to the lower water activity (aw-value). Beet root powder will most likely keep its colour a lot longer than the juice itself. Take into account that whenever using beet colourants you might also change the flavour of your recipe since you’ll need quite a lot and since the colour will have some beetroot flavour.

Betalains can undergo a variety of chemical reactions, some of which stabilize the colour, but most of which change the colour. Enzymes can be one cause for loss of colour. Another is the Maillard reaction. Since beet colouring often still contains some sugars a browning reaction can occur which makes the red a lot less red, especially since the colour itself is also not super heat stable. That said, solutions have been found that should improve its heat stability, for example through the addition of anti-oxidants. I haven’t tested these products, but there are several out there, for instance this one from Sensient.

Carmine

Carmine is an example of a natural food colourant. It is made from bugs. By crushing these insects a bright red pigment can be obtained. It is approved for use in Europe and has number E120. Carmine is a popular natural colourant because it is very stable. Most natural colourants cannot withstand heat or extreme pH-values. Carmine however is stable under heat, light and oxygen, it is the most stable of all red natural colourants.

carminic acid food-info net
Structure of carminic acid, the colourant in carmine. Source: food-info.net

Carotenoids

Carotenoids are another very common group of natural colourants. They occur in carrots, tomatoes, oranges and a lot of other fruits and vegetables. There is qutie a wide range of colours of carotenoids, a common red carotenoid is lycopene, which sits in tomatoes. Lycopene can also be manufactured using micro organisms which can produce the colour molecule. A lot of carotenoids can be manufactured in other ways then via extraction from a plant. Carotenoids are a common source of nature identical colourants.

Another common source of red carotenoids is paprika which is used in a lot of sauces to colour them red. Most carotenoids are fat soluble but tend to be susceptible to oxidation, causing them to lose their colour. On the other hand they tend to be stable at higher temperatures. Various companies are working on carotenoid colourants and on ways to stabilize them further.

 

Erythrosine

Last but not least, erythrosine is another example of an artificial food colour. In the US Erythrosine is also known as Red #3 whereas in Europe it has received the number E127. It may be used in various products and seems to be a very stable colourant, however, limited information is available on this colour.

Using red colourants in baked goods

Overall, if you’re using artifical food colours, you’re bound to not run into a lot of issues. Artifical colours are very stable, will not be affected by the high temperatures in the oven nor the composition of your cookie or cake. However, if you’re using natural colours, you might want to pay closer attention. Should you add some extra acids to stabilize the colour? Or should you do a baking test on forehand to see whether the colour will survive the oven?

All in all, making a bright red cake isn’t as easy as it may seem, especially if you’re using natural colours!

Sources

Food-info.net, article describing azo dyes and carmine

EU commision regulation 231/2012 on additives, version 18-8-2017

The Kitchn, discussing whether you can use red beets for colouring a red velvet cake and discussing the challenges

Handbook on Natural Pigments in Food and Beverages: Industrial Applications for improving food color, 2006, edited by Reinhold Carle, Ralf Schweiggert, chapter 4 Betalains, link

Re-evaluation of Erythrosine (E 127) as a food additive by the EFSA, 2011, link

Downham, A., Colouring our foods in the last and next millennium, 2000, link

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