In general, a high ratio cake is any type of cake that is prepared with a relatively high amount of sugar in the recipe, especially when the sugar content is compared to the amount of flour that is used. This type of cake is characterized by a taste that is made exceptionally sweet, owing to the higher sugar content, and the tendency to be very moist in comparison to cakes that contain less in the way of granulated sweeteners.
Usually, a proper high ratio cake will require the use of specially formulated flour and shortening. The shortening is usually emulsified, which helps to lend more smoothness to the texture of the finished cake. The flour is usually ground into very fine particles and may be heat treated or chlorinated to allow the particles to blend quickly with the high sugar content and the liquids used in the recipe. There are bleached flour and whole wheat flour blends that are ideal for use in this type of cake.
Eggs, water, and milk are the typical liquids of choice in sugary cakes of this nature. As a rule, the three liquids are mixed separately from the dry ingredients, then slowing worked into the mix of flour and sugar. Other flavorings can be added at the discretion of the baker.
When it comes to the amount of sugar that is contained in a high ratio cake, there is some difference of opinion. There are those that consider any cake recipe that calls for a ratio of more than one part sugar to three parts flour to be high ratio. Others believe that any recipe for a sugary cake including more than one part sugar to two parts flour qualifies. Just about everyone agrees that if a recipe calls for as much sugar in the mixture as flour, then the finished product can properly be referred to by this term.
One advantage of a high ratio cake is that it tends to stay fresh at room temperature longer than some cakes that contain less sugar. However, it will begin to mold more quickly when wrapped in plastic wrap or confined in a small, covered cake plate.