Sweet Purple Potato Coconut Sponge or Chiffon

The texture of this cake is soft, moist and spongy because of the high sweet potato content, which is really good at retaining moisture (even in breads). The coconut goes awfully well with the sweet potato and the baking aroma was amazing.

There is some science to the lovely purple hue when I was researching on the net. Apparently, people have been getting bluish grey tone. The colour in purple potato reacts with acid and turns red, it reacts with alkaline and turns bluish grey. So adding some lemon juice to the purée will help you get the purple Colour. Avoid adding baking powder or soda.

The current taste is less sweet, up the sugar by 10g if you like, especially if the sweet potato you have gotten is not sweet enough.

Recipe (adapted from Bean Panda)

  • 70g purple sweet potato puree
  • 1-2 tsp lemon juice
  • 60g coconut milk
  • 4 egg yolks
  • 35g caster sugar
  • 1/3 tsp salt
  • 50g cooking oil
  • 75g cake flour
  • 2 tbsp milk (optional)
  • 4 egg whites
  • 55g caster sugar
  • 1/4 tsp cream of tartar


1. Boil potato with skin intact till soft. Remove skin, mash and strain through a sieve to get 70g of purée. You can also steam it by cutting into slices first.


2. Add lemon juice and mix well, see the deep red.


3. Add coconut milk and mix.


4. In a separate bowl, beat egg yolks, salt and sugar till light and fluffy. Then add the oil.


5. Add in potato purée in 3 batches and whisk till all dissolve.


6. Add the sifted flour and fold gently till no trace. If batter is very lumpy, add the 2 tbsp of optional milk. Set aside.




7. Beat egg whites till frothy, add Cream of tartar. Keep beating and add sugar in 3 batches till firm peak.

8. Add 1/3 of meringue to yolk batter to lighten it. Pour yolk batter back into meringue and fold gently with spatula till evenly mixed.



9. Pour at a height into 7″ Chiffon tin. Tap a few times on counter top. Bake at 165 deg C for about 30 min till skewer comes out clean. Actual time depends on your oven as one reader took 45 min. Invert to cool.



15 Comments Add yours

  1. Marie says:

    Hi, can i use ur recipe for 17cm tube pan?


    1. oladybakes says:

      Mine is a 7″ tube pan, so pretty close. You will have some excess which you can bake in cupcakes.


  2. Cassandra says:

    May I ask what is COT?


    1. oladybakes says:

      It’s cream of tartar.


  3. Paisan says:

    Which eggs size?


  4. SusanH says:

    The colour of your sweet potato chiffon is lovely. Thank you for the tip regarding the use of lemon juice. May I know how many grams (approximately) of raw/uncooked sweet potato on will generate 100gram of purée?
    Thank you, SusanH


  5. Annie says:

    Hi my cake pan is 20cm. Does this, recipe size for 20cm or 18cm can pan


    1. oladybakes says:

      Mine is for a 7” tube pan, quite close.


  6. Jacqui Lim says:

    Can I bake this in a 7inch round regular pan?
    I don’t have a tube pan?


    1. oladybakes says:

      Can but cake will not rise as high.


  7. Thesochiabakes says:

    Just made this cake. I find the flavour very light and the colour did not turn out as lilac as yours. Probably some ube powder / paste would have helped (just like pandan paste in pandan chiffon cakes). I used large eggs, so I had too much batter to fit in a 7” tube pan. I ended up using a 7” and a 5”. Baked in 30 mins.


    1. oladybakes says:

      Thanks for feedback, colour is challenging with this cake, some tell me the entire cake turned grey. I usually use 60g eggs with shell.


  8. Mama Mia says:

    Hi,the colour of your purple chiffon is beautiful . Can you tell me which purple sweet potato you used, the one with the whitish skin or the reddish brown skin ? The whitish skin sweet potato is more easily available in Melbourne.
    Thank you for sharing.


    1. oladybakes says:

      I used the purple skin one.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s