Angel Food Cake: crushed pineapple instead of sugar?

Sugar is not used as a sweetener in cakes, it is a major component which creates the needed texture. As such, it is very difficult to impossible to replace.

In angel food cake, you absolutely cannot replace it. Angel food is a fragile cake without chemical leaveners, and depends on a very well balanced ingredient list. Using a fruit puree instead of the sugar will create a mess. Also, the tube pan is important for angel food cake, unless you are willing to bake very thin separate layers, else the cake won't bake properly.

If you really insist on replacing the sugar, the least risky base would be a pound cake, since it is relatively insensitive to extra moisture. The basic ratio there is 1:1:1:1 of eggs, sugar, flour and butter by weight. If you are extra careful in reducing the moisture of your puree - maybe drying the pineapple in a low oven for several hours after it has been pureed - you will likely end up with something edible. It will be quite far from the original, and it would be better classified as a fruitbread than as a cake, but at least it is likely that it won't bake into a brick or remain a sticky underbaked mess. Other types of cake won't be as forgiving.

Angel food cake gets it's characteristic texture from the egg foam on which it's structure is built. The flour and, to a lesser degree, the sugar stabilize the foam so it's less fragile.

Adding more flour will change the texture of the cake to be more... cakey. That is, not as springy as we expect from an angel food cake. I don't know what the texture of the foam will be without any sugar. I suspect it will be drier.

Pineapple won't be able to replace the function of sugar because it can't be fully Incorporated. In fact, many angel food cake recipe even use powdered sugar as regular sugar is too coarse.

If you are satisfied with the texture changes of no sugar, you can certainly fold in pineapple chunks when the batter is folded together. I would recommend canned to avoid the risk of protease enzymes in fresh pineapple damaging your structure-- egg foam is all protein after all.

I have never tried this but if I were to do this experiment, I would cut out part of the sugar but leave some for the texture. Then I'd place canned pineapple slices on the bottom of the pan and make an angel food pineapple upside down cake.

You do need a tube pan for egg foam cakes like angel food and chiffon because they are mostly air and don't conduct heat well to their interiors. Tube pan are cheap and easy to find at thrift stores. In a pinch I've had success using a regular cake pan with a clean, empty can or canning jar in the middle. Made it tricky to invert the cake at the end but it worked.

Aside from whether it's a good sugar substitute in other ways, pineapple contains an enzyme called bromelain which digests proteins. Be careful how you use it as it may have undesired effects - for example pineapple jellies will not set properly as the bromelain prevents it from doing so.

Since the angel food cake recipes I've seen contain egg whites, there may be some reaction between the protein and the pureed pineapple there. This may be mitigated if the pineapple is cooked first (and I believe canned pineapple is cooked) as I think this denatures the enzyme.

Also seconding what another user said though, sugar is sugar.

I have managed to bake a cake with no sugar whatsoever, using only baked pineapple, flour, and egg whites. The cake came out very tasty but extremely soggy since either I added too many cups of pineapple or not enough flour (I followed my own recipe).

If someone wants to make a sugar-free pineapple cake, here is my advice:

1. The pineapple should be extremely sweet and ripe.

2. I roasted pineapple for 40 minutes prior to baking to get rid of the enzyme that could ruin the egg whites.

3. If I had to do it over again, I would add a yolk and I would decrease the number of eggs and would put less pineapple to make the dough less runny.

4. I used parchment paper all over so it didn't burn even though I didn't use a tube pan.

5. Next time, I would use the following ingredients: 3 egg whites (possibly one egg yolk?), 1 cup of sifted flour, 1/2 cup of sweet baked pineapple and I would get a bigger pan because otherwise, it won't be dry all the way through.

Enjoy!