Banana Bread (Bread Machine)

After receiving a bread machine for my birthday last year, I immediately sought out a recipe for banana bread. It’s one of my favorite foods and I wanted to find an easy way to make it at school; a bread machine recipe seemed like the perfect solution. I found this recipe and adapted it to accommodate my roommate’s vegan eating preferences. In this post, I will explain the role of each ingredient in the original recipe, then explain how to substitute more bananas for the eggs and why such a substitution works. The recipe can be found at the end of the post, or you can click over to this post for a recipe card. 

Banana bread is a kind of quick bread, meaning it uses a fast-acting chemical leavening agent(s) instead of yeast (a biological leavener). Other kinds of quick breads include muffins, coffee cakes, waffles, and pancakes (Bastin). Quick breads can vary in their look, taste, and ingredients, but they all have the same basic components of fat, sugar, flour, eggs, and a leavening agent (Bastin, “Science of Baking”). The original recipe for this banana bread calls for all-purpose flour, baking powder, baking soda, white sugar, vegetable oil, two eggs and two ripe bananas.

The main role flour plays in baking is the formation of gluten. Flour contains the proteins glutenin and gliadin; when met with water, these proteins begin to link together and create an elastic gluten network. This gluten network works to trap expanding gases in the dough as it bakes. The amount of protein present will affect the gluten network; this amount is determined by the kind of flour you choose. A flour with a higher percentage of proteins, such as bread flour, will create a stronger gluten network and is good for making bread or biscuits. On the other hand, a lower percentage will lead to a weaker gluten network and a more tender final product (“Science of Baking”). All-purpose flour is a good middle ground – it contains between 10-12% protein. To aid gluten formation and create a stronger gluten network, you can add more water or mix the dough for a longer time. When making a quick bread you usually want a tender, cake-like result, and therefore should avoid overmixing the dough in order to prevent a strong gluten network (Potter pp. 218-220). 

Baking powder and baking soda are both chemical leavening agents. These are usually preferred over yeast when making cakes or quick breads because they’re faster-acting and don’t have the same distinct flavor as yeast (Potter p. 239). Both baking soda and baking powder react with an acid(s) to create carbon dioxide bubbles in the batter. These bubbles expand when the batter is heated, giving lift to the final product. Baking soda needs an acidic ingredient in the batter to react with, while baking powder is a combination of baking soda and a solid acid (usually cream of tartar). When dissolved in liquid, the baking soda and cream of tartar begin to react with each other. Most baking powders are double-acting: they contain a fast-acting acid which is activated by moisture in the batter, as well as a slow-acting acid which is activated by heat and gives the cake a second lift while baking (Bastin, Potter p. 239-248). 

Sugars include monosaccharides such as fructose, galactose, and glucose, and disaccharides such as sucrose, maltose, and lactose. White table sugar is the result of extracting sucrose from sugarcane and sugar beets. It is used in baking as a sweetener and affects the tenderness and texture of the finished baked good (“Sugar”). Sugar also caramelizes when exposed to heat, leading to a pleasant aroma, flavor, and color in a baked good (“Science of Baking”). When sugar and fats (such as butter or shortening) are creamed together, they create pockets of air that lead to a light and tender finished product (Bastin).

Oils are fats that are derived from plants. They are made up of triglycerides that contain various fatty acids and are liquid at room temperature. In baking, oils affect the texture, moisture, and tenderness of a baked good (“Oil”). Oil also helps prevent gluten formation by coating the flour; because oil is hydrophobic, it slows the interactions between the water and the proteins in the flour (“Science of Baking”). 

Eggs serve varied purposes when it comes to baking. Whipping egg whites can add air to a mixture, thus giving eggs a leavening property; eggs can also provide structure and add liquid (Potter 394). Eggs help provide structure to baked goods through their proteins. In raw eggs, the proteins are coiled up; when heat is added, they begin to denature, or uncoil, before realigning with each other to create a new network. The denaturation process creates a three-dimensional structure which traps water and helps solidify the baked good. Eggs also contain the emulsifier lecithin, which brings together hydrophobic (water-fearing) and hydrophilic (water-loving) components such as oil and water (Compound Chem, “Science of Baking”).

Choosing a substitute for eggs necessitates an understanding of the role the egg plays in your recipe. Eggs work as emulsifiers, they help stabilize a baked good, they can act as a leavener, and they add moisture (“Egg Replacement”). In this recipe, bananas also contribute structural and moistening qualities, making them a good substitute for the eggs. However, bananas don’t have the same leavening effect as eggs, and you may need to compensate by adding more of your leavening agent if a good lift is important (such as in cakes or cookies) (Wakefield). You should substitute 1/4 cup of mashed banana for each egg (Potter p. 394), but this of course depends on the size of the eggs and bananas. My rule of thumb is to substitute one small, ripe banana for each large egg.