Hi

I made some cupcakes the other day using the ratio of ingredients given
in one of my cookery books for the "classic sponge", i.e:

equal parts fat, sugar, egg and S.R.flour

(hand beating the fat and sugar then gradually adding the egg followed
by mixing in the flour.

When looking at various other recipes for cakes based on those four
ingredients the ratios vary.

From a "scientific" point of view, what general effect do the different
ingredients have on the texture and physical properties of the cake?

A more specific question - for one batch of cupcakes I used vegetable
oil for the fat, agave syrup for the sugar and oat flour. It tasted very
nice but it was too crumbly.. how would I tweak the proportions of those
ingredients to make it hold together better - increase the egg content
or fat maybe?

Thanks
Bigus