If a recipe includes a lot of acid such as lemon juice and buttermilk and isn't lifted with enough baking powder, the cake will taste dense. In that case, you may need the addition of baking soda which will react with the acid and create a fluffier crumb.
Two Main Types of Cake
Foam cakes have little to no fat, and usually have a larger proportion of egg. This gives them their lighter, airy texture (think angel food and sponge cake). Butter cakes on the other hand contain butter, margarine, or vegetable shortening, giving you the dense, moist cakes we know and love.
Most cakes will call for a leavening agent like baking powder or baking soda. These create the bubbles you need for the cake to rise. If the flour you use is self-raising, it already has a leavening agent in it. Make sure your butter is room temperature, and beat the butter and sugar together until properly creamed.
Cakes that are too small for their weight will usually be dense and feel wet, while those that are larger may be too airy or dry. A good volume indicates a good rise and ensures a great appearance.
A dry cake is usually the result of one of the following pitfalls: using the wrong ingredients, making mistakes while mixing the batter, or baking the cake too long or at too high a temperature. Once you understand how to avoid the common cake-baking blunders, you'll bake a moist cake every time.
Take an oven-safe dish and fill it with water. Turn your oven on to low heat (325°F or 160°C) and allow the water to heat up until the oven is filled with steam. Then place your cake on an oven-safe tray and pop it in the oven above the steam bath. Allow the cake to have about 5 minutes in the steamy oven.
Milk: Add MILK, not water, when your box mix calls for liquid. The milk adds density, fat and, most importantly, extra flavor to your mix. Egg WHITES: Not adding the yolks to the cake makes the cake fluffy and whiter!
Specific Gravity is a way to measure the air added into cake batter. It shows the amount of aeration, or air movement, in specific batters, allowing bakers to determine if it is too dense or not. It's the ratio of the weight of a cake batter in a container compared to the weight of water in the same container.
Why Does It Matter? When you overmix cake batter, the gluten in the flour can form elastic gluten strands – resulting in a more dense, chewy texture. The white batter looks airier, while the red looks thick and dense.
Cake typically becomes dense from using the wrong type of flour, overmixing, overbaking, using too little or expired leavening agents, or using the incorrect measurements of ingredients.
Baking is an exact science, and recipes often contain exact proportions that you must use to achieve your desired result. So, if you use four extra-large eggs instead of four large eggs, you will add too much egg to a batter, which could result in a product that tastes eggy and is spongy and dense.
If there isn't enough egg, your batter or dough may not be able to hold its structure or could end up overly dry or dense. On the other hand, if there is too much egg, your baked goods could lose their shape due to excess liquid, or have a rubbery (or even overly cakey) texture depending on the recipe.
Find out the rule of thumb for how much baking powder to flour to add to your cake recipe. Baking powder is an essential leavening agent in baking, for creating lighter cakes that aren't overly dense. Baking powder opens up the crumb of a cake giving cakes a lighter mouthfeel.
Baking Soda
It's used to chemically leaven doughs and batters when it is mixed with an acid. Combining baking soda with an acid produces a chemical reaction that releases carbon dioxide gas which causes the food to expand and become fluffy. Think about light and airy pancakes. That's the baking soda at work.
Bicarbonate of soda is much more powerful than baking powder, so it is recommended that you use around 1/4 the amount of bicarbonate of soda when using it to replace baking powder (eg. if the recipe calls for 2tsp. baking powder, use 1/2 tsp. bicarbonate of soda).
If you've got a flat cake on your hands, you may have overbeaten your ingredients. Overmixing ingredients can create a dense batter that doesn't get that same airy rise. Mismeasured baking powder (too much or too little) may also give you a flat cake.
Milk in cake recipes, generally makes the texture lighter and stronger (thanks to the protein and lactic acid),. Adding the right amount keeps the cake from being dense. Milk (and other liquids) actually activates other ingredients in the cake batter like leaveners (baking soda, baking powder).
Over-mixing your batter prevents the leavening agent from rising up like normal and traps it inside the batter where it creates tunnels and big holes. Mix just until the ingredients are combined to create light and fluffy cake layers. Be sure you're using the right leavening agent.
Over mixing acts on the gluten in flour and will make cakes hard instead of the lovely soft spongy texture we associate with a good cake. Insufficient creaming of sugar and eggs will also make a tight texture because there isn't enough air trapped in the mix to give it a lift.
Avoid over-mixing of flour as it activates the gluten amount, which makes the cake hard, and as a result, you will get a rubbery cake. Always check the freshness of your baking soda and powder, as it plays a very crucial role while baking a cake. Proper measurement is the key to getting a perfectly baked cake.
Microwave It
This will gently heat your cake and soften it up immensely. If you do choose this method to quickly soften your cake, I recommend eating it immediately. Once you microwave a slice of cake, it will go from nice and soft to even harder than before in a matter of minutes.