Sponge Basics

Before I started this section I had made 3 sponge cakes; a total of 3 in all the years I have been baking. I had eaten plenty of them but never felt the need to make them. It was so easy to go to the shops & buy; a sponge cake or lamingtons or sponge fingers (for Tiramisu) or a Swiss roll or ginger kisses. That is it is easy if you're not on a gluten free diet. When I started making gluten free sponges I used at least 45 dozen eggs in 6 weeks. I now do not know how many sponges I have made. But I do know that they are one of the quickest cakes to make & bake.  

There are two requirements for making sponge cakes successfully. The first is the ingredients and their amounts in relation to each other. The second, equally important, is the amount of aeration in the batter that is sufficiently stable to stay there while cooking and remain while cooling. Without the second it will not be a sponge. Essentially sponges are all about aeration, aeration, aeration.

Wheat based sponge cake recipes appear to vary considerably in their ingredients - there are so many recipes on the web. However most of them are based on 3 ingredients - eggs, flour & sugar. The vast number of recipes usually differ in the type of flour used & amount of flour used in relation to the other ingredients. One of my "textbooks" I frequently refer to is "The Professional Pastry Chef - Fundamentals of Baking & Pastry, 4th Edition" written by Bo Friberg. The following is a quote from his book (pg 430);

"The flour used in a sponge cake must have a good ratio between starch & protein. Some gluten (a high percentage of which is found in bread flour, for instance), is necessary to bind and hold the structure, but too high a percentage makes the batter rubbery and hard to work with and results in a tough and chewy sponge. A flour with too much starch, such as cake flour, will produce a light and tender sponge, but the structure will collapse partially when baked."

Okay, essentially this means that professional chefs if making a sponge may add starch to decrease the effect of the gluten present in "all purpose" wheat flour. Gluten is a remarkably stretchy protein but it is still only a protein and we know that gluten is not needed for making cupcakes (refer to Section on Proteins). So for gluten free sponges we have the starches but need to add in additional protein.

If you don't want to use Bakers' Magic gluten free flour (there are a number of sponge cake recipes on the website using this flour) what combination of starches & protein (from flours) are the best to use when making a gluten-free sponge? 


Currently there are three easily accessible starches; Maize, Potato & Tapioca (refer to Section on Starches). Potato starch is my first preference followed by Maize starch & lastly Tapioca. A sponge made from potato starch is moister than a maize starch sponge however it does not have the same height. My family think that they are better than sponges containing wheat flour. I love my daughters comment for my potato starch/flaxseed flour sponge “It is so soft, like a pillow that’s just been fluffed.” The resulting sponge may sink a little when it comes out of the oven (& therefore wouldn't win any CWA awards) and this is dependent on how much starch is used.

Does the addition of a little bit of flour help maintain structure for the sponges? It certainly does, the photo below is of sponges containing a little; black rice flour (it stands out), cocoa (it also stands out), red lentil flour (on the right with the green icing), teff flour (far side of the cocoa) or only starch (in between some of the others). These are only a few of the gluten free flours available so how do you know which one to use? 

Overall I have tried; Amaranth, Besan, Blackbean, Buckwheat, Carob, Chestnut, Cocoa, Coconut, Flaxseed, Garbanzo & Fava, Red Lentil, Lupin, Millet, Moong, Quinoa, Rice (Black, Brown, Glutinous & White), Sorghum (Red & White), Soy & Teff

Adding too much flour to the sponge batter will deflate it. Coconut tastes great but is fantastic for deflating the batter - I only use it in modified sponge recipes.

The green light group; Buckwheat, Carob, Chestnut, Cocoa, Flaxseed, Red Lentil, Sorghum & Teff.  I think these flours are the best to add to stabilize the sponge batter (my preference is cocoa, flaxseed & teff). However the amount used is relatively small ~1 tsp to ~2 tbsp (for a 6 egg sponge) sifted into the starch.

The gritty group; Millet & Rice (Black, Brown & White) these flours worked however the resulting sponges were slightly gritty. The black rice flour sponge does have a distinctive colour & this could add to the overall appearance of a dessert.

Deflaters & awful tasters; This is my & my family's opinion on the taste however I can't see myself making a sponge with this group again. Amaranth, Besan, Blackbean, Garbanzo & Fava, Lupin, Moong, Quinoa & Soy.

How much starch should be used?

Quite a few recipes for sponges are based on the ratio of 2:1:1 for eggs, flour & sugar; that is, recipes that contain wheat flour. The weight of the eggs refers to the yolk and white combined after shelling. A dozen eggs that are sized as 700 g may vary between 49 to 56 g each (to make it easier I use ~50 g/egg) - the variation will be greater if you use eggs from your own laying hens. Following this ratio means that if you use 4 eggs (50 g x 4 = 200 g) then you will need 100 g of flour & 100 g of sugar. If we use this ratio & substitute starch for flour the resulting cake will collapse. The ratio needs to be adjusted.

While working out suitable ratios for potato starch I noticed that if the amounts of sugar & starch were the same the cake would collapse so in this case there has to be more starch than sugar. Increasing the amount of starch (without adding any additional flour/protein) will stop the cake collapsing but the resulting sponge is quite heavy & chewy. The ratios differ between the two starches I used. To cover all bases I have included ratios for light, medium & heavy sponges. 

Potato Starch Sponge Ingredient Ratios

Eggs (g)*: Starch (g): Sugar (g)

Light, but will sink out of oven 2: 1.1: 0.85

Medium, sinks a little 2: 1.34: 0.85

Heavy, will not sink 2: 1.67: 0.85


Maize Starch Sponge Ingredient Ratios

Light, but will sink out of oven 2: 0.85: 0.85

Medium, sinks a little 2: 1.1: 0.85

Heavy 2: 1.3: 0.85

* The weight of the eggs refers to the yolk and white combined after shelling. A dozen eggs that are sized as 700 g may vary between 49 to 56 g each.  4 eggs will be approximately 200 – 210 g, the corresponding amount of potato starch needed is (100 x 1.1) 110 g and the sugar is 85 g. 

I usually make a light potato sponge using;

6 Eggs (700 g/dozen)

165 g Potato starch

130 g Caster sugar

1 tsp Cream of tartar

1/2 tsp Bicarb of soda

If there are dietary restrictions and you can not use either potato or maize starch it is possible to use tapioca starch with a small amount of flour from the green light group. Tapioca starch sponges are more dense than ones made with either potato or maize starch. The addition of teff flour (can use up to 25 g for a 6 egg sponge) produces the best tapioca sponge, the second best is one with the addition of red lentil flour (can use up to 10 g for a 6 egg sponge). If using tapioca starch follow the ratios for maize starch.


Castor sugar is the best to use as it is finer and dissolves more readily than normal table sugar.  If you don’t have castor sugar you can use normal table sugar, it will dissolve but will take slightly longer.  Brown sugar can be substituted in a recipe if you prefer the flavour and/or colour to that of castor sugar.  The amount of sugar can be increased a little, if a slightly sweeter sponge is required. However too much additional sugar affects the ratio mentioned above and increases the likelihood of the sponge sinking when it comes out of the oven. When the ratio of sugar : starch is 1 : 1 the cake will partially collapse (the light maize starch sponge).

I have substituted liquid sweeteners for caster sugar in the sponge recipe. Sponges usually have no added liquid, the only liquid comes from the eggs used. The sponges (photo below) contain different sweeteners, both solid and liquid. Those made with the liquid sweeteners (agave - 2nd layer from the top right hand side and rice malt syrup - top layer) have sunk a little. If I were to make these again I would use the ratio for the medium or heavy sponge.  


I can remember years ago (20+) having a discussion on what eggs to use with an elderly woman who would win prizes for her sponges in a local show (a country town with a population of ~10 000). After making sponges using eggs that were so many days old she assured me 3 day old eggs were the best (Apparently her mother-in-law had told her that her sponges weren't that good so winning at the show was very important to her!). I haven’t repeated her experiment so I don’t know for sure but if/when I have my own laying hens I will probably use eggs that are 3 days old. 

Incorporating air into the batter

Essentially there are two ways to incorporate air into the batter; by whisking it (mechanical) or by adding leaveners (chemical). I have never made a sponge without whisking the eggs but I have made them without leaveners. As it is very easy to add a bit of cream of tartar & bicarb to the starch I use both methods.


The eggs & sugar are whisked/beaten together until the mixture is light & fluffy. Sounds easy & it is, however there are a couple of different ways to do this.

  • Whole eggs & sugar are whisked together
  • Whole eggs & sugar are whisked together at ~42 C
  • Eggs are separated; whites are whisked separately, yolks are whisked with the sugar
  • Eggs are separated; whites are whisked with a bit of sugar, yolks are whisked with a bit of sugar

The temperature of the egg makes a difference to the volume of the egg & sugar mix. Using eggs straight from the fridge is out - don't do it - they need to be at least at room temperature. Warming the egg & sugar mix to 42 C helps the sugar dissolve but I am sometimes an impatient cook & do not want to be standing around with a thermometer in a mixing bowl trying to keep the mix at a specific temperature. Nor probably do you.

To warm the eggs (I keep mine in the fridge) I fill my small kitchen sink (a container would be fine) with hot tap water & put the eggs in there for approximately 10 mins. Hot tap water is ~55 C after 10 mins in it the eggs are ~37 C (if they have come from the fridge). Putting the eggs in water is also handy for checking for bad ones (they float).

To separate or not? I have tried 3 of the above combinations - I gave the 42 C method the flick. It was much easier for me to get consistent sponges when I separated the eggs & whisked both whites & yolks with sugar. In a 6 egg sponge I whisk 5 whites with 50 g of sugar (whisk attachment) & 5 yolks + 1 whole egg with 80 g of sugar (flat beater). 

How long do you whisk the mixture? Using my KitchenAid stand mixer I whisk the egg whites for ~1 1/2 - 2 minutes - until it has ~quadrupled in volume. The yolk mixture takes longer to become light & fluffy (ribbon stage), I usually whisk/beat it for 9 minutes. Below are photos of the yolk mix prior to beating & when it has reached the ribbon stage.

yolkmix200011   ribbon300011

Combining the dry & wet ingredients

Once again there are a couple of different ways of combining the ingredients. For me, the easiest is folding the sifted starch mix through the yolk & sugar mix (ribbon stage) until the combined mix is uniform. It will deflate a little. I mentioned before I can be a little impatient in the kitchen - now is one of those times (the mix may deflate more than necessary). I then fold in the whisked egg whites to this mix. The sponge batter is now ready to be baked.

My timeline for making a sponge

Put eggs in hot tap water for 10 mins in small kitchen sink.

While eggs are warming up; bring out the appropriate equipment, sift together starch & leaveners, grease cake tins, cut out baking paper for bottom of tins.

Measure out sugar into two mixing bowls & turn oven on to 175 C.

Separate yolks & whites, put them in with the sugar.

Beat egg yolks & sugar for 9 mins. Stir the egg white & sugar mix, rest this mixing bowl on top of the hot tap water to help the sugar dissolve. 

If necessary while egg yolks & sugar are mixing continue with the pan/tin preparations.

Whisk the egg whites & sugar for ~2 mins.

Fold in starch mix to yolk mix.

Fold in whites.

Transfer sponge batter to two cake tins.

Bake for ~18 mins.