The DIY guide to creating all the colours of the rainbow.
By
Kylie Walker

20 May 2019 - 1:08 PM  UPDATED 20 May 2019 - 1:08 PM

“My nanna was onto it 30 years ago,” says Caroline Griffiths. “Simply mash a strawberry or two with icing sugar for a beautifully coloured icing for her sponge.”

Griffiths is chatting about her tips and tricks for creating easy, all-natural food dyes from fruit and vegetables – a topic that’s gaining popularity these days with more people dealing with food allergies, and others just wanting to avoid artificial chemicals in what they eat.

“If there are alternatives to artificial colours, why not use them? I’ve had a few friends with children that have reactions to the artificial colours, especially red, so it was with this in mind that I decided to do my Rainbow cake [pictured above] with natural colourings,” says Griffiths, the author of several cookbooks including Incredible Bakes (Smith Street Books, $39.99) and Breakfast Bowls (Smith Street Books, $29.99).

The layers of her colourful cake (get the recipe here) show some of the shades that can be created with natural dyes; some plants produce subtle shades, like those shown, while other options, such as dried fruit powders and garden greens, can produce bright, vibrant colours in cakes and icings.

Wedding cake maker and keen gardener Hayley McKee, whose first book Sticky Fingers, Green Thumb (Hardie Grant Books, $29.99) was published in March, is a big fan of using garden produce to make DIY dyes.

“Whether it’s custom-made cakes or my cookbook recipes, my whole approach to baking is to lean on nature for taste and looks. Natural colourings are easy to use, and have an earthier tone and truer taste than artificial dyes,” she says. “It’s nice to know you’re using pure ingredients to colour your sweets instead of a batch of unknown additives. I love using sweet peas, turmeric, saffron, raspberries, blueberries, pumpkin, carrot and beetroot. Delicious and vibrant!”

Here’s how you can create your own all-natural food dyes.

Pink, red and purple

“For a pink buttercream or cake batter I like to roast baby beetroots and grate them down or purée them into the mixture. Cook out any extra moisture in the purée by heating it gently in a saucepan  - this brings out the colour and flavour too. Remember, a little purée goes a long way so add a teaspoon at a time until you get the right tone,” says McKee. 

Put McKee’s beet technique to work in her beetroot truffle cake - baby beets lend a dense, fudge-like texture to an already deep, dark chocolate base (the recipe includes instructions for a two-layer cake, or the multi-layer tower shown). 

Beetroot and rose truffle chocolate cake

Griffiths, too, is a fan of beetroot for “pink to red and all the shades in between” (the pink layers in her rainbow cake show how adding more or less of the same colouring can produce quite different results). Blackberries and blueberries can give mauves and blues, and strawberries yield shades of pink. Blueberries are great for purple, too: “For a blast of purple, simply blitz up some fresh or frozen blueberries and add to your butter cake, cookie dough or creamy toppings,” says McKee.

“You can get a cool purple with red cabbage, but can’t use too much as the flavour can be quite pungent!” Griffiths says.

McKee like the flavours that some dyes bring to her creations.

“Most of the time, fruit and vegetables only add a subtle layer of flavour but I actually enjoy the depth it brings to baked desserts. If you’re only using a dash of natural colouring, chances are you’re only going to get a whisper of the taste.”

And for something that's a deep, definite red, like red velvet cake? McGee’s tip: “For a red velvet cake I’d use beetroot or freeze-dried raspberries to add the hit of red. I’d combine the dye to the buttermilk so that I could gauge the intensity before folding it through the cocoa batter.”

A finely sieved puree of cooked beetroot is what Desiree Nielsen uses in the pretty pink cream cheese crowning glory on her chocolate cupcakes with pink velvet icing, in her show The Urban Vegetarian

Chocolate cupcakes with pink velvet icing
Chocolate cupcakes with pink velvet icing

Blue

Blueberries are an obvious choice, but if you grow cornflowers, these also make a beautiful food dye. (Follow these tips on how to use flowers to make natural food colourings – you can infuse the petals in water to use immediately, or dry and grind the petals to store for later use.)

Green

“Blanching spinach leaves in boiling water then squeezing out the green juice is a simple way to add a touch of evergreen to icings,” says McKee, who uses spinach water in the dough for the two-tone cookies in her new book,  and rocket in the icing (get the recipe here).

Sticky Fingers book and cookies

Avocado brings a soft green colour along with a lush texture to icings (give Grittith’s baked vanilla doughnuts with avocado coconut icing a try), while pandan can give bright and soft greens (take a look at this recipe for pandan lamingtons).

Baked vanilla and pea doughnuts
Baked vanilla and pea doughnuts

Yellow and orange

Saffron and carrot are go-to options here. Infuse liquid ingredients with saffron, and turmeric to a wide range of recipes (such as the vibrant Lebanese turmeric and aniseed cake below) and use carrot juice to colour batters and icings (see the rainbow cake recipe for instructions). In her book, McGee also suggests using golden beets, in similar methods to red beets; golden sweetcorn juice as a milk substitute in recipes; and sweet potato and pumpkin in cake batters, buttercreams and fillings.

Turmeric and aniseed cake - sfouf

More tips and tricks

  • Another technique McKee recommends is swirling vegetable purees into freshly whipped cream.
  • Looking for something really vibrant? “Freeze-dried fruit powders can add great colours too, and are now readily available online. I love red dragon fruit powder, also known as red pitaya, raspberry powder and butterfly pea flower powder [to create blues]. You can also get blue spirulina, black activated coconut charcoal, and matcha powder, which makes an interesting green,” says Griffiths.
  • Use natural colourings in all kinds of recipes and decorations, Griffiths says. “The vibrant, crazy colours from the dragon fruit powder and blue spirulina are fun to add to smoothie bowls (explore Griffith’s smoothie bowl recipes here), homemade banana ‘nice cream’ and to use in icing/frosting. The vegetable colourings work really well on shredded coconut for ‘sprinkles’.” (Find instructions for colouring coconut in the rainbow cake recipe.)
  • "I’ve been playing with butterfly pea flowers steeped in water. The flowers once soaked in warm water leach an incredible inky blue pigment. Once diluted it becomes lighter blue and then when you add the acid of lime or lemon juice it turns pink! My kids have been enjoying fun ice blocks in their water and I’ve been enjoying fun ice blocks in my G&T!" Griffiths says. 

"Give it a go! It’s very satisfying to create desserts that reflect the seasons and lean on your garden patch or market fresh produce," McKee says.

Join Desiree Nielsen in The Urban Vegetarian, with double episodes airing Mondays at 7.30pm on SBS Food (Channel 33). 

Discover more of Hayley McKee's work at her Sticky Fingers Bakery website. Find Caroline Griffiths on Instagram and explore more of her baking recipes using less-refined sugars here

Colour from nature
Avocado & matcha smoothie bowl

This bowl was inspired by my travels in Vietnam, where avocado is often used in delicious smoothies. Avocado is an intriguing and totally underrated ‘sweet’ ingredient. 

Blue pea flower dumplings

If you haven't ventured into blue pea flower territory then these dumplings are a vibrant way to jazz up your steamy offering. 

Baked vanilla and pea donuts

Peas? Yes, really! We use lots of vegetables and fruits to add natural sweetness to our baking, so why not peas? They are unusual, but rather fun, I think. These donuts are also equally delicious dipped in chocolate glaze. Garnish with frozen peas for added texture if you like.

Pandan lamingtons

Who doesn't love a lamington? Here’s a colourful variation on the great Aussie classic. For best success, the cake should be day old so it absorbs the icing better; make it the day before you need it.  (You can even use a store-bought one for ease).  

Totally Unicorn beetroot cake

"If you’re turning up your nose at what seems like an unlikely marriage, try it first. The combination of earthy beets, bitter with smoky dark chocolate and slightly salty cream cheese is heavenly! Totally Unicorn is a heavy metal band and my brother-in-law, Mikey, is their illustrious drummer. Whenever they go on tour and stay with us, this is what they get for supper after a night of intense head banging." Poh Ling Yeow, Poh & Co.