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The Chemistry of... Cake
Transcript of The Chemistry of... Cake
The major difference between all cakes is the density. History People in England began to make cakes in the 1700 and 1800s. Bread slowly evolved into sweet desserts that we now call cake. The biggest difference between bread and cake was the lightness and fluffiness. This was achieved when bakers stopped using yeast and began to use eggs and/or baking soda or baking powder. Definition:
An item of soft, sweet food made from a mixture of flour, shortening, eggs, sugar, and other ingredients, baked and often decorated. Basic Ingredients... Flour:
The main purpose of the flour is to give structure and substance to the cake.
When the proteins in the flour mix with water, (or other liquids) gluten is formed. Connecting to the World... Technology:
Technology has come along way since the 1800s. People who baked back then would most likely have used wood-burning ovens. People also used huge stone ovens as well. Now, ovens can be powered by gas and electricity in a matter of minutes. Baking food a few hundred years ago would have been a day affair. Now it takes less than an hour, thanks to technology. Applying What We Learned... Based on our knowledge of what certain ingredients do in the cake-making process lets figure out what's missing. Chem 20-1
Dec. 2012 The Chemistry of... Cake Simply put, baking soda is a stronger, more concentrated version of baking powder. Gluten gives elasticity to dough or batter and helps it rise and keep its shape. It holds the final product together. The trouble with gluten is if you have too much your cake will be tough and chewy, too little and it will crumble. Nevertheless, it is essential. Baking Soda or Baking Powder:
Some cake recipes call for one, some call for the other.
This is a very important feature of cakes. It gives it the airiness that distinguishes it as a cake. The baking soda (sodium hydrogen carbonate) becomes sodium carbonate, water, and carbon dioxide, making the cake have little holes in it.
NaHCO3 Na2CO3 + H2O + CO2 Those little air bubbles of CO2 get trapped in the cake and make it fluffy.
Be careful though, too much baking soda will make the cake flop because of all the air inside. Not enough baking soda will make your cake more like a brick.
1/4 teaspoons of baking soda or 1 teaspoon of baking powder will be enough to leaven (puff up or expand) 1 cup of flour. Eggs:
The eggs bind the cake together. Eggs, just like the flour, have long chains of proteins (amino acids) in them. The egg WHITE:
Proteins in the egg white are uncoiled by the heat of the oven. This helps in making the cake puffy. Too much egg white and the cake will be chalky and dry. The egg YOKE:
The egg yoke is one of many ingredients that add richness and moisture to the cake. But, to much and the cake will be wel. Fats (Oil, butter, or margarine):
The fats' role is almost counter intuitive. Although we want gluten to form so the cake can stay together, we do not want it to form too much or very strongly into gluten. (Remember, this will make it tough)
The fat will coat the proteins in the flour, preventing some proteins from forming with water to produce gluten.
(Audience demonstration) Fats will prevent the cake from being too chewy. Instead it will be tender. Butter or vegetable oil will also moisten the food so it is not dry. Sugar and Milk:
The sugar adds sweetness (no surprise).
Milk, which is a sugar lactose, keeps the cake moist. It also bonds with proteins to stop gluten formation. When you see a cake get golden brown, these are the ingredients at work The chemical formula for sucrose:
Although most cakes only have a small amount of table salt (sodium chloride with iodine) in them, they play an important role. Gets rid of bitter tastes and balances the sweetness. Helps the batter to be elastic. A chemical reaction occurs between charged amino acids (proteins) and ions of salt. The two react together to form gluten fibers. Thus, contributing to the texture. and
As bread bakes, the gluten protein coagulates.
The gluten is no longer elastic and determines the cake size and shape. This change is permanent, it does not reverse when the cake is cooled.
The end result after taking the cake out of the oven and cooling it, should be a firm, but light textured dessert. In Depth Look... Societal:
Cakes are a common dessert in most households in Canada. They are served when guests visit and for most birthdays.
Beyond this though, mass production of packaged, already made cakes supplies jobs for many people in factories.
There are many cake decorating television shows and companies around the world. A diverse cake industry has supplied many jobs for people. Audience Engagement and Involvement: Test or examine each of the three mini cakes and predict what is missing. Then compare with normal cake.