red velvet roll cake with cream cheese frosting

Guide on Red Food Coloring – Artificial vs Natural Colors

Whoever decided to make red velvet cake must have had some strong bright red color at hand. Red velvet cakes also contain a good amount of dark brown cocoa powder. It’s not easy to color these products red. Unless, that is, you have a strong red color at hand.

What’s more, to make a red velvet baked good, that color shouldn’t just be strong. It should also survive the baking process. Else you’ll still end up with something brown.

Not every red color will be able to do so. To find out, we’ll do a deep dive into the world of red food colors. Discussing anything from artificial bright reds, to unstable, but natural reds made from cabbage.

On red food coloring

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

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

On artifical vs natural colors

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

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

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

Anthocyanins

Anthocyanins are a very prevalent natural food coloring 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 coloring 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 color 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 color remain red.

Also, this color tends to be a lot weaker than artificial colors. In other words, you might need a lot more of the color and that can affect your recipe from a consistency but even flavor 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 artificial food colorants. 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 important with regards to its color 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 colors 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 color 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 color made the bright red velvet cake you see in the photo at the top of this post. The color 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 as additive number E129, in the US it has number 40. Both regions use a different way of naming food colors and have different procedures to allow a new food color. Allura red AC is one of the most commonly used red colors 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 colorant this is often a challenge. Not a lot of other food colorants are as stable.

Others

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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-dyes are Amaranth (E123) and red 2G (E128). There are less common in foods. Ponceau 4R (E124) can be found in food colorants online.

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

beetroots
Freshly sliced beetroot, bright red.

Betalain – Beetroots

The molecules responsible for the bright red color of beetroots are betalain molecules. These are a separate group of natural food colors, 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 color. Therefore, beetroot juice cannot be stored for long without losing color. That said, certain antioxidants and so-called chelating agents can help to stabilize the color. 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 color. 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). Beetroot powder will most likely keep its color a lot longer than the juice itself. Take into account that whenever using beet colorants you might also change the flavor of your recipe since you’ll need quite a lot and since the color will have some beetroot flavor.

Betalains can undergo a variety of chemical reactions, some of which stabilize the color, but most of which change the color. Enzymes can be one cause for the loss of color. Another is the Maillard reaction. Since beet coloring often still contains some sugars a browning reaction can occur which makes the red a lot less red, especially since the color itself is also not very 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 colorant. 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 colorant because it is very stable. Most natural colorants 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 colorants.

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 colorants. They occur in carrots, tomatoes, oranges and a lot of other fruits and vegetables. There is quite a wide range of colors of carotenoids, a common red carotenoid is lycopene, which sits in tomatoes. Lycopene can also be manufactured using microorganisms that can produce the color molecule. A lot of carotenoids can be manufactured in other ways than via extraction from a plant. Carotenoids are a common source of nature-identical colorants.

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

freshly sliced orange, purple and yellow carrots
Carrots, purple, yellow and white varieties.

Erythrosine

Last but not least, erythrosine is another example of an artificial food color. 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 colorant, however, limited information is available on this color.

Using red colorants in baked goods

Overall, if you’re using artificial food colors, you’re bound to not run into a lot of issues. Artificial colors 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 colors, you might want to pay closer attention. Should you add some extra acids to stabilize the color? Or should you do a baking test on forehand to see whether the color 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 colors!

References

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 coloring 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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3 Comments

  1. It seems cherry tomatoes recently have become a very rich dark red. Is this natural or are growers adding a red colour?

    • Hi R.

      I’m not an expert on tomato growing but I would seriously doubt whether they’d be able to add a red colour to their tomatoes. What I would expect on the other hnad is that they’ve developed new varieties of cherry tomatoes with a brighter red colour or that they’ve been ripened differently. There’s quite a difference possible between varieties. Hope that helps!

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