chocolate babka, with orange peel

Why to use (orange) zest in baked goods – Chocolate babka

Not too long ago I felt like baking something new and saw a beautiful photo flashing by of a chocolate babka. It looked like delicious, a bread (I love bread in case you forgot) with chocolate (which I also happens to enjoy quite a bit). So I decided to give it a try and it was indeed delicious…

One of the reasons it tasted so good was that slight hint of orangy flavour. The recipe used some orange zest to lift up the flavour and despite the fact that it was only little, it worked wonderfully well. There’s a good reason for using this orange zest (or peel, they’re the same) and not just the orange juice. It’s got quite a nice background in food chemistry, so a perfect topic for a post I would say.

The orange, its structure and the peel

As discussed in a post dedicated on oranges, an orange is composed of several different sections. The inside is a fleshy fruit on the inside with its vesicles full with juice. The other important section is the peel. The peel protects the fruit against heat, dehydration, insects and other pests.

The peel again is made up of two layers, the so called ‘flavedo’ and the ‘albedo’. The albedo is the white spongy layer on the inside. When using orange peel you don’t want to use this white interior. It doesn’t have the nice aromas (is slightly bitter) and has quite a fibery texture.

Instead, most recipes will focus on using the outer (orange) layer of the orange, or the flavedo. This orange layer is made up of various components, such as waxes as well as various polymers and fatty acids. This layer also contains so called oil glands. These are tiny pockets of oil inside this peel. The oils serve as a defense system for the orange. However, it’s also these oil glands that have a strong flavour and aroma. A lot of flavour components are dissolved in the oil.

Using orange peel/zest instead of juice

When making orange peel we just use that section of the orange which has all these great flavours, the flavedo. By grating the orange carefully we can collect just this outer layer with all those oils and fatty acids that we want.

All in all, the orange peel (and thus zest) contains so many oils, with oil soluble aroma’s. The juice on the other hand contains mostly water and water soluble aroma’s. The water and oil soluble aroma’s taste and smell very different though! It’s as nature had wanted it, the oils should fight pests, etc., whereas the fruit is most likely meant to be eaten to spread seeds. So they should be and taste different. A reason for using the zest is really this different taste sensation, however, there are more reasons.

One of these is the difference in concentration. As you can imagine the flesh and inside fruit are mostly water. The concentration of flavour aromas is lower than that of the peel. Orange juice is fairly diluted, so in order to get a good punch of orange you might need quite a bit of juice. And even when using it, it might partly disappear again during the baking process. Orange peel on the other hand has a great punch of flavour in just a little bit of volume! That way you’re not messing with liquid:flour ratios and you can simply add it as a flavour, keeping texture intact.

Orange zest extract

In a previous post we’ve discussed the extraction of vanilla using rum. In the post we discussed that the flavour components from vanilla can be extracted by using alcohol. The same actually goes up for orange zest. This can also be made into an extract.

Since most of the flavours in zest are oil soluble they tend to dissolve in ethanol quite well. Learn more about making such an extract in a separate post.

Chocolate babka with orange peel

Once we know where orange peel comes from, it’s time to use it. I’ll be sharing a chocolate babka recipe which contains orange peel, but doesn’t necessarily taste like orange very strongly. I found this recipe on Broma Bakery and adjusted it slightly.

chocolate babka, with orange peel

Why to use orange peel in baked goods – Chocolate babka

  • Author: Science Chef
  • Prep Time: 30 mins
  • Cook Time: 30 mins
  • Total Time: 1 hour
  • Category: Sweet bread



  • 360g flour
  • 60g sugar
  • 2 tsp yeast
  • 90 ml water
  • 0,5 tsp salt
  • orange zest from one orange (add more for more of an orange punch)
  • 2 eggs
  • 75g butter

Chocolate filling (yum!)

  • 40g butter
  • 75g dark chocolate (I like extra dark)
  • 40g icing sugar
  • 40g cocoa powder


  1. Mix the flour, sugar, yeast, salt and orange zest in a bowl of a stand mixer.
  2. Add the eggs and the water and mix at a low speed (or knead by hand) until the dough comes together. If it doesn’t come together add a little bit of water at a time until it does.
  3. Mix at a low speed for about five minutes.
  4. Add the butter and mix for another 10 minutes.
  5. Cover your bowl with plastic and leave to rise at a warm spot (I put it in a 40C oven) for at least 45 minutes.
  6. Make the choclate filling by melting the butter and chocolate in the microwave or au-bain-marie (in a bowl above a pot of boiling water). Once there molten and mixed in, add the icing sugar and cocoa powder and mix it into one mass.
  7. Knead the dough shortly by hand and roll it out into a flat sheet. Spread the chocolate mix over the surface (the chocolate makes it taste great, so make sure to use it all!).
  8. Roll it into a loaf and leave to rise in a baking pan for another 30-45 minutes.
  9. Bake the loaf in an oven pre-heated at 190C for approx. 30 minutes.

Besides using orange peel, this recipe demonstrates another interesting sciency fact. As you can read, the recipe calls for kneading in the water first, before adding the butter. This is essential in order to develop gluten. If you wouldn’t do this at first, you might risk making more of a flaky consistency, then the airy bread you’d like to. Gluten development is such a common and important topic that I’ve spent a whole blog post discussing it!



Some of the sources I used for this post: JB Tech Food, A study on the appearance of an orange, on oils in citrus fruits or learn more about the chemistry of orange oils.

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