Purple Sweet Potato Chiffon 紅芋シフォンケーキ

i bought some really beautiful purple sweet potatoes during the weekend and immediately set my eyes on this. i've seen this on several blogs and the violet amethyst-like cubes embedded within the cake really caught my attention. i guess i just hv this weakness for pretty desserts (and purple sweet potatoes).



the cake turned out fluffier than i thought, consider that the purple sweet potato puree was rather thick and heavy. tastewise its pretty mild since the sweet potato doesn't really hv much taste/aroma to begin with but i do like the subtle sweetness and the contrast of the cubes with the cake. i also think that they're better eaten fresh from the oven coz that raw eggy smell will be more apparent upon cooling.



recipe is adapted from here and the original yields a 17cm cake but i scaled it up since i only hv a 22cm tin. also, i don't like the idea of using cream of tartar when whisking egg whites coz i don't see a difference in the results. japanese pastry chefs don't use it in their recipes either so i'll usually omit. sugar and egg whites alone will give you a beautiful meringue so you don't need cream of tartar, or vinegar, or lemon juice.

ingredients (makes one 22cm/8.5" cake) :

130g purple sweet potato

4 tbsps milk

4 egg yolks

25g brown sugar

65ml canola oil

4 tbsps water

110g cake flour, sifted

5 cold egg whites

65g caster sugar

80-100g raw purple sweet potato cubes, lightly coated with cake flour to prevent from sinking to the bottom of the cake

directions :

1. peel and chop purple sweet potatoes, then steam until cooked. lightly mash with fork, add milk and puree with hand blender until emulsified.

2. in a bowl whisk together egg yolks, brown sugar, oil & water until well blended. add in sweet potato puree and mix well. fold in flour until well combined.

3. in another bowl whisk together egg whites and caster sugar until stiff peaks, then fold the whites into the yolk mixture in 3 additions. fold in the purple sweet potato cubes.

4. pour mixture into ungreased chiffon/angel cake tube pan and knock the pan against the counter top to remove some air bubbles.

5. bake in a preheated oven of 180C for 40 mins or until a wooden skewer inserted into the cake comes out clean. remove tin from oven and immediately invert it until the cake has cooled completely.