You’ve probably heard of the old adage “Cooking is an art, while baking is
a science.” So what does that mean? Why is baking a science? For starters,
baking relies on chemistry and it requires precision. Throw in a handful of
this or a pinch of that might work for cooking, but when it comes to
baking, the outcome can change with just the slightest adjustment to a
recipe.
If you are not precise when measuring baking powder, your cake could
collapse; if you mix your batter using too many turns, you may end up with
a hockey puck instead of a moist cupcake; and if you use butter that’s a
few degrees too warm in your pie crust, you could have a soggy crust.
When we bake, we rely on recipes to guide us through all the chemical
reactions that take place while mixing or kneading, heating or baking,
cooling or whipping. Baking involves all sorts of chemical reactions:
- Protein coagulation
- Water evaporation
- Caramelization & browning
- Enzyme reactions
- Expanding gases
- Thickening starches and etc.
Take cakes, for example. Each ingredient has a job to do. The proteins in
the flour bond and create gluten and this provides the cake’s structure;
baking powder and baking soda react with acidic and alkaline ingredients to
release carbon dioxide, adding bubbles to the batter which helps the cake
expand and have airiness; eggs bind all the ingredients together; butter
and oil tenderize; sugar caramelizes, browns and tenderizes; milk and water
provide moisture; and yogurt, juice, fruit sauces and other acidic
ingredients help balance flavor, tenderize and add moisture, and they react
with leaveners to help give rise.
Baking introduces your child to science in a fun and rewarding way,
teaching them skills that will help them understand better how things work
and the world around them.
Acidic and Alkaline Ingredients
The pH scale measures the degree of acidity and alkalinity of a substance
on a scale from 0 to 14. The midpoint is seven and represents neutral;
below seven is acidic and above seven is alkaline. Successful recipes have
a balance of acidic and alkaline ingredients to achieve a neutral pH
because this results in the best flavor and texture. Knowing the acidity or
alkalinity of your ingredients and understanding how acidic and alkaline
ingredients work together can help ensure your baked goods will turn out
the way you intended. With practice, you will be able to develop your own
recipes, which can be great if your child or another family member has
allergies.
Baking soda, a chemical leavener, is alkaline and is used when there is an
acidic ingredient in the recipe. Examples of acidic ingredients include
applesauce, buttermilk, yogurt, honey, brown sugar, molasses, lemon juice,
vinegar and regular cocoa powder (not Dutch-process or alkalized cocoa
powder – which is neutral). When baking soda comes in contact with an
acidic ingredient and is moistened, the alkali/acid combination creates
carbon dioxide, and this helps the batter to rise.
If your chocolate cake recipe calls for buttermilk and you use regular
milk, there wouldn’t be a release of carbon dioxide to give it that fluffy
texture that makes cake so special. The recipe likely calls for baking
soda, which is alkaline, and it reacts with the acidic buttermilk to allow
the cake to rise. In addition, the color of your cake and the taste won’t
be as appealing.
Adding the right amount is important too. If you were to add one-half
teaspoon baking soda to your cookie dough when the recipe calls for
one-quarter teaspoon, you might end up with over-browned, burnt-tasting
cookies. And if you don’t add enough, you might end up with something more
like a muffin than a cookie. Too much baking soda can also create soapy
off-notes, and too little will allow acidic flavors to come through too
strong.
Baking powder, on the other hand, has both alkaline and acidic ingredients
in it and is slightly acidic – almost neutral on the pH scale. It reacts in
two phases – when moistened and when heated – and the gas won’t be released
until baked. You will usually see baking powder in a recipe that has an
alkaline ingredient in it, such as milk, but it can be found in other
carefully crafted recipes as well.
How they work
Here’s how these leaveners work: the baking powder and baking soda start
acting immediately when you put your cake batter in the oven. They expand
the air bubbles previously beaten or mixed into the batter and held by the
flour’s gluten strands. At the end of baking, the flour’s starches firmly
set around the expanded air bubbles and the batter conforms to the shape of
the pan and browns. When you cut your cake after baking, you should see
tiny, evenly spaced holes or air pockets.
If the holes are big and uneven, you possibly added too much baking powder
or baking soda, which can cause the gluten strands to weaken and not have
the ability to hold in the excess carbon dioxide (air bubbles) before the
cake’s flour starches have set, thus spilling over. On the other hand, if
you add too little baking powder the cake’s structure may set too soon, it
won’t be able to rise – resulting in a hockey puck cake.
Yeast, another leavener, consumes available sugars and creates carbon
dioxide as a byproduct. Whipped egg whites also act as a leavener when
folded into batter.
Sugar, Salt, Eggs and Flour
Sugar has many functions in baking. It caramelizes foods when it breaks
down from heat. It’s also responsible for browning foods when it binds with
amino acids – a process known as Maillard reaction. It also draws in
moisture from the surrounding air, which helps slow the cake from
hardening. When a cake begins to go stale, the starch starts to
crystallize. Sugar will draw in moisture and prevent the starch molecules
from forming and crystallizing.
Salt does more than just round out flavor. It draws water out of foods and
in baking, it regulates fermentation. Yeast needs water to perform its
function. Salt hinders the yeast and thereby slows the leavening process.
It also helps strengthen the dough; without salt, the dough would be a
sticky mess. The negative ions in the salt balance out the positive charge
in the gluten. Too many positive charges push the gluten apart.
Eggs are filled with protein. When heated, their proteins unravel and
realign to form a solid out of a liquid, giving structure to a baked good.
Flour has two types of protein – glutenin and gliadin. When water is added
to flour, the proteins come together to form a new protein called gluten.
When heated, the starch portion of the flour gels with the help of sugar
and creates a web-like structure that traps water and provides moisture.
The carbon dioxide from the leavener expands the cake and the gluten holds
the bubbles in place.
It’s important to know the protein content of flour. For example, you don’t
want to use a high-protein flour when making cookies. High-protein flour
has more gluten than all-purpose flour and is better suited for bread as it
gives strength and structure. Cookies are crumbly, chewy and crunchy. They
need a lower protein flour.
There is a lot more science in baking than what we covered here –
emulsification, friction, air pressure and heat are just a few things
you’ll learn if you bake frequently. If you know your ingredients and how
they behave, you’ll have a good chance at success.
Originally published: 06-01-17
Updated: 10-31-22
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