The chemistry of cake making

Published : 11:01 am  July 18, 2015 | No comments so far |  |  (669) reads | 

cak2by Therese Motha
Most housewives don’t realise that a cake recipe is like a chemistry formula. Many of the ingredients must  be there, or the  recipe simply won’t work. Generally speaking, cakes are made from flour, sweetening, fat, egg, leavening, liquid  and flavouring,  the variety and proportions changing with the type of cake wanted. But how does this chemistry work? Moisture added to flour causes gluten to develop from the protein, and this forms the elastic network  that is the framework of the cake. 

Fat and sugar add tenderness, then during baking, the framework puffs to make the cake light  by the expansion of the air bubbles captured in the batter  by creaming the fat, by beating the eggs, or by the carbon dioxide released by the leavening. Sugar is the main flavouring,  and increases tenderness and volume as well as helping with the browning. Fats help tenderising, and may be butter, margarine, shortening, lard or oil. Oil, though, cannot be used interchangeably with solid fat and requires special recipes. Eggs add colour, flavour and nutritive value, act as leavening agents, and help keep  fat particles suspended in batters for greater smoothness.

Leavening agents are usually baking powder, baking soda  and air. A simple explanation of the action of baking powder is that it is a combination  of baking soda  and an acid ingredient  which react in the  batter  to form gas bubbles  that expand during baking  to make the cake rise. When there are already acid ingredients in the batter (such as buttermilk, brown sugar, honey, chocolate, fruit juice) , baking soda is used. The acid in the ingredients react with the soda to give the same effect as baking powder. Air in beaten egg whites  leavens angel food cake  and true sponge cake  and assists in leavening  other cakes, where whites are  folded in  at the end of mixing.

Why do we sift flour? To introduce air into the mixture, making a lighter end product. The liquid may be just eggs, or it may be milk, water, fruit juice  or other things that serve to moisten the mixture, and make the leavening work, as well as allowing the dry ingredients to be blended. Cream of tartar is another ingredient  that appears in certain types of cakes . It is an acid  and is important in an angel food  cake, since it helps keep the cake from shrinking  by strengthening the cell walls  of the egg whites . Without it, the cake is cream coloured, instead of white.

The right pans are important to the success of cakes. Also, use the pan size called for. Too large a pan means a thin cake that bakes too fast , and is dark on the bottom  but still pale on the top , with a tough, coarse texture. Too small a pan  may cause the cake to spill over  the edge, or have a sticky layer on the bottom. With cakes, it is important to measure  accurately. Basically, there are two types. Foam type cakes, and creaming type cakes (or butter cakes). Foam type cakes get their name from the light, fluffy texture that beaten egg whites give, and include angel food, sponge and chiffon cakes.

Angel food cakes are made with egg whites blended with the flour and sugar, while sponge cakes are made of whole eggs (beaten separately), and true sponge cakes have no leavening other than eggs. Remember when making this type of cake, that eggs separate more easily when cold, but egg whites beat to a better volume  when at room temperature. When beating egg whites, be sure not a speck of yolk or other fat gets into them  or they will not beat to stiff peaks. It is a good idea, when separating eggs, to drop each egg white into a small bowl before adding it to the large beating bowl. That way, if a yolk breaks,  the whole bowlful of whites won’t be ruined.

Creaming type cakes are made by creaming fat and sugar until fluffy, then beating in eggs, and stirring in dry ingredients and liquid alternately, either by hand or with the mixer. Creaming the fat and sugar well is important, because you want to get lots of air in the batter for a light, fluffy cake. But once the dry ingredients are added, the batter should be mixed gently, so the gluten isn’t over developed.

There is also a foam type cake, which is not a true sponge because it uses baking powder in addition to eggs for leavening. Another method of making creaming type cakes is the quick mix method. The dry ingredients are sifted into the mixing bowl and the fat and milk are beaten in. For the final step, the eggs are added, and the batter beaten again. The resulting cake is very light.
Whichever method you choose to make, your cake will be a success  if you follow these rules carefully.