The Science of Cooking

Kitchen Chemistry for Ordinary Chefs

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Anonymous asked: Hey, Sarah! Sometimes when some people make guacamole, they put their avocado pit in the bowl to keep it from turning brown. I understand the browning is from oxidation... so how does an avocado pit keep the guac from oxidizing? Is this just an old wives tale? -Sam Mockford

Hi Sam! Great question! As you said, guacamole browns quickly because of oxidation, reactions that occur when the guacamole comes in contact with the air. The avocado is especially vulnerable to oxidation because its cells contains an enzyme called polyphenol oxidase (PPO). When the avocado is cut up, some of the cells break, releasing this enzyme and allowing it to react with the flesh of the avocado in the presence of oxygen from the air. Polyphenol oxidase changes the chemical structure of compounds called phenols, composed of 6-membered rings, in the avocado, which results in a color change.

SO2PPOR©Ben Rotter

So, if the avocado pit prevents the guacamole from turning brown, one of two things much be happening. Either the avocado pit somehow changes the chemical composition of the guacamole, preventing the action of polyphenol oxidase (which would be AWESOME!!) or the pit simply prevents oxygen from coming in contact with the guacamole.

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Dr. Harold McGee, a professor at Yale, conducted an experiment to find out what was really going on, as detailed in his book The Curious Cook: More Kitchen Science and Lore. He found after significant exposure to the air, only the area of the guacamole directly under the pit had not undergone oxidation. Replacing the avocado pit with a lightbulb had the same effect! Dr. McGee concluded that it was just the physical blocking of the avocado pit that prevented of oxidation. I found this experiment conducted with photos included on a blog, DesiScrub. The link is listed under my sources.

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No visible difference here!

Since the pit won’t completely cover the guacamole, it isn’t very effective in preventing oxidation. Better strategies include covering the guacamole with plastic wrap; in Dr. McGee’s experiment, he found that Saran wrap was most effective since it prevented more oxygen from going through than other brands. The plastic wrap should be gently pressed down onto the guacamole to eliminate as much oxygen as possible; some suggest putting something light, like salsa, on top to ensure that the plastic wrap continues to cover the surface of the guacamole and does not move.

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 Refrigerating the guacamole can slow down the oxygen of the enzyme as long as the temperature isn’t colder than average-avocados are especially at risk for chilling injury. Also, polyphenol oxidase doesn’t react well in acidic conditions, so adding lime or lemon juice will help prevent browning. refrigerated-avocado acidified-avocado

Of course, like most foods, guacamole is best when it’s fresh!

Sources:

DesiGrub. (2010, December 20). Avocado browning. Retrieved from http://desigrub.com/tag/pit-and-guacamole-browning/

USDA Agricultural Research Magazine. (1998, February). Keeping Freshness in Fresh-Cut Produce.

Harold McGee. (1992). The Curious Cook: More Kitchen Science and Lore. Hoboken, NJ: Wiley.

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I think it is a sad reflection on our civilization that while we can and do measure the temperature in the atmosphere of Venus we do not know what goes on inside our soufflés.

Nicholas Kurti

Source: Friday Evening Discourse at the Royal Institution, ‘The Physicist in the Kitchen’. In Proceedings of the Royal Institution (1969), 42/199, 451–67

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Anonymous asked: I've been noticing a lot of products lately carrying the label "gluten free." What is gluten and why the labelling?

Gluten free labels are indeed springing up everywhere, and I’ve had the same questions myself. I wondered if it was a warning for people with allergies or if gluten was generally unhealthy; it turns out neither is correct. Here’s what I found.

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Gluten is an elastic protein found in wheat, rye, and barley. Examples of products containing gluten include bread, bagels, and pizza crust. Gluten can be found in any recipie where water and wheat flour are mixed. Wheat flour contains the proteins glutenin and gliadin, both gluteneous proteins. When combined with water, these proteins bind to each other. As they are mixed, the proteins form vast interconnections, creating sheets of gluten.

Gluten is essential in making dough rise. When dough containing wheat flour is mixed and kneaded, the gluten sheets trap in air bubbles. These air bubbles come in contact with yeast, a microorgansim that converts simple sugars in the dough into ethanol and carbon dioxide, and carbon dioxide gas forms. This further enlarges the air bubbles, and the dough rises.

When the dough is put into the oven and heated, the yeast produces carbon dioxide even more rapidly. In addition, the ethanol produced by the yeast undergoes a phase change into a gas when heated, inflating the bubbles even further. The gases expand until the yeast dies due to the intense heat of the oven. The gluten firms as it cooks, and when the final product is removed from the oven, it contains many air cells with fine linings. This creates a unique texture.

800px-BaguettesOnBreadBoardForTableServiceMatthew Roy

Gluten is best when strength and elasticity are needed, but will ruin recipes that are meant to be light and airy. For example, gluten is perfect in yeast breads, puff pasty, pasta, and pizza. However, in cakes, quick breads, muffins, and pancakes, chemical leaveners like baking soda and baking powder are much more effective. Gluten is also not required in many recipes that use eggs, since egg proteins are capable of forming extensive networks.

A cook can control how much gluten is present through the flour used. Most all purpose flours, bread flour, and durum wheat all contain a large amount of protein used to form gluten. Cake flour, self-rising flour, and instant flour have less protein and can be used effectively will chemical leaveners to guarantee a soft, tender product.

Some products are labeled gluten free because a sizeable number of people in the United States have an automummine disorder involving a negative reaction to gluten. This is called Celiac Disease, and according to the Celiac Disease Foundation, 1 in 133 adults in the United States experience it.  

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©Celiac Disease Foundation 2011

When gluten enters the small intestine, it comes in contact with small projections of the intestinal wall called villi. These villi break down food via embedded enzymes and absorb nutrients. In individuals with Celiac disease, the gluten triggers a reaction causing the immune system to attack the villi. Damage occurs, and villi may even be destroyed. This makes it difficult for the intestine to break down food and will hinder the absorption that occurs at the intestinal wall, leading to deficiencies in nutrients. Symptoms like cramps, bloating, and diarrhea occur, and if untreated, the disease can be life threatening.

At the moment, the most effective treatment is for patients to have a gluten free diet. Thus, companies have responded by labeling their food as “gluten free.” This makes it easy for the patient to know that they will not have a negative reaction to the food and creates a market for producers. Those of us who do not have Celiac disease don’t need to worry about it; gluten is not unhealthy for most people.

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©Celiac Disease Foundation 2011

Sources:

Celiac Disease Foundation. (2011). Retrieved from http://www.celiac.org/index.php

Corriher, S.O. . (1997). Cookwise: the hows & whys of successful cooking with over 230 great-tasting recipes. New York: William Morrow and Company, Inc.

deMan, J.M. (1999). Principles of food chemistry. Gaithersburg, MA: Aspen Publishers Inc.

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How to Be a Successful Chocolatier

The Lenten season is almost upon us, and it reminds me of a few years ago when I decided to give up chocolate. It was a struggle, but somehow I endured through the intense cravings. I still remember on Easter day, finally being able to sink my teeth into a chocolate bunny. It was the best chocolate experience I can remember. While most of us find it easy to stuff ourselves with chocolate, preparing it is not so simple. I have memories of instantly ruining entire bowls of melted chocolate before it even made it into my chocolate molds. What is it that makes chocolate so sensitive? How can mistakes be avoided to achieve a perfect chocolate dessert?

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 There are two problems that came up continously during my chocolate making adventures-seizing and burning. Let me describe seizing to you. You are stirring your bowl of chocolate, admiring its creamy beauty. You stop to spoon some chocolate into a mold, look back, and suddenly notice your chocolate is now grainy! What happened? 

Water. Only a few drops can cause this effect, which can come from many places, such as from damp utensils, licked fingers, and even steam from the stove! According to Dr. Richard A. Schwatz at the Wilber Chocolate Company, this is due to the “sugar bowl effect.” If you dip a wet spoon into a bowl of sugar, the water on the spoon binds the sugar crystals together like a glue, creating small hard lumps of sugar on the spoon. However, if you pour an entire cup of boiling water into the sugar bowl, there is so much water that the sugar crystals will completely dissove.

 Chocolate consists of very fine dry cocoa particles in cocoa butter, and a little moisture will cause the particles to stick together like the sugar stuck to the wet spoon in the previous example. The problem can be resoved by adding enough water to moisten all the cocoa particles. As a result they will no longer stick together, like the sugar crystals when the cup of boiling water was added to the bowl.

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Note the fine dry texture of the cocoa particles

 Surprisingly, many chocolate recipies do not have enough liquid in them to prevent seizing, so it is important to analyze the ingredients before hand. For every two ounces of chocolate, there must be at least one tablespoon of liquid to avoid seizing. When preparing the chocolate, its safest to melt the chocolate along with the butter or liquid in the recipie rather than seperately.  

The other problem that often arises when making chocolate is burning, and unlike seizing, its effects cannot be reversed. This is because at the relatively low temperature of 130ºF, cocoa butter seperates from the cocoa particles, which will then burn. However, since chocolate contains a variety of fats in addition to cocoa butter, to be completely melted, the chocolate must be heated to around 120ºF. This is only ten degrees away from the temperature at which chocolate burns! Thus, the temperature of chocolate must be closely monitored. 

If big pieces of chocolate are melted, the outside, which melts first, might get too hot and burn before the inside has even started melting. To prevent this, chocolate should be chopped into smaller pieces. Constantly stirring the chocolate will guarantee that the chocolate will melt evenly.

 Best of luck on all your chocolate endeavors!

Corriher, S.O. . (1997). Cookwise: the hows & whys of successful cooking with over 230 great-tasting recipes. New York: William Morrow and Company, Inc.

deMan, J.M. (1999). Principles of food chemistry. Gaithersburg, MA: Aspen Publishers Inc.

Potter, N.N., & Hotchkiss, J.H. (1999). Food science. New York: Springer.

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When we decode a cookbook, every one of us is a practicing chemist. Cooking is really the oldest, most basic application of physical and chemical forces to natural materials.
Arthur E. Grosser (Professor of Chemistry at McGill University) The New York Times, May 29, 1984

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All About Cookies!!

My Great Grandma Hammer’s chocolate chip cookie recipe was the first I learned to prepare on my own. I had a high motivation to do so; her cookies are delicious! In my opinion, they have the perfect amount of crunch. However, some say they prefer cookies that are chewier. I wondered what makes different cookie recipes taste so different and was surprised by how many different factors there are! Read on to find out what to look for in a recipe to guarantee that your cookies will be to your liking.

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Baking my great-grandma’s chocolate chip cookies with my mom, who passed down the recipe to me

Let’s start with fat. There are many different fats that can be used, such as butter, shortening, and margarine. The choice of fat not only impacts the flavor but the texture and spread of the cookie on the baking sheet. This is because different fats have different melting points and water content. Shortening contains 100% fat. Since it doesn’t contain water, a cookie made with shortening will be firm. Additionally, shortening retains its texture over a wide temperature range, so over the course of baking, the cookie will not spread much on the sheet and the cookies will be thicker. Butter and margarine contain around 80% fat. Since they contain more water, they will make the cookie softer and puffier due to steam. Unlike shortening, butter and margarine melt quickly when they reach a certain temperature, so the cookies spread out shortly after being put in the oven. These principles can be combined. For example, my grandma’s recipe calls for both margarine and shortening, which makes her cookies thick and puffy.

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Another factor is flour, which influences the cookies texture and color, depending on how much water it is capable of absorbing. If flour contains a high amount of protein, the parts of the protein that are attracted to water will bind it, in a sense soaking it up. This makes cookies more crisp, more flat, and less crumbly.  A greater amount of protein in the flour also makes cookies darker. Conversely, cake flour or low protein flour doesn’t bind up water, so more water can turn to steam in the oven. This will make the cookies more tender and puffy. The cookies will also be lighter in color.

The type of sugar used in cookies influences browning and crispiness. Table sugar has low moisture content and crystallizes as the cookie cools, which makes the cookie crisp. Brown sugar is similar to table sugar but contains molasses. It’s able to absorb moisture from the atmosphere, which will make the cookie soft after it’s removed from the oven. My grandma’s cookies contain a blend of table sugar and brown sugar, making the cookies both crispy and tender. Adding corn syrup can make the cookie browner since it requires a lower temperature to brown than table sugar.   

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A small amount of liquid, usually less than a tablespoon, in the form of milk or water is usually added. It provides steam to create a puff in the cookie. However, if too much is added, the cookie will spread too thin.

The lecithin and proteins in eggs, when heated, form networks that hold the egg together. See my earlier post, 2/14/11, for more information on this.

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Finally, baking powder and baking soda leaven the dough, as described in my 1/31/11 post. Adding slightly more baking soda can neutralize additional acidity to make the cookies browner.

Now that you’ve read all about cookies, why not give baking them a shot? Below is Great Grandma Hammer’s chocolate chip recipe:

Grandma Hammer’s Chocolate Chip Cookies

Beat together:

1/2 cup margarine

1/2 cup shortening

Add and mix:

 3/4 cup golden brown sugar

 3/4 cup white sugar

Add and mix:

2 eggs

1 teaspoon vanilla

Add at once and mix until just until combined:

1 teaspoon baking powder

1 teaspoon baking soda

3/4 teaspoon salt

2 cups flour

Stir in by hand or at a very low speed:

2 cups oatmeal (quick or old fashioned)

1 (16 oz.) pkg. semi-sweet chocolate chips

Drop by spoon full onto cookie sheet.

Bake at 350 degrees for 12-14 minutes.

 

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Sources:

Corriher, S.O. . (1997). Cookwise: the hows & whys of successful cooking with over 230 great-tasting recipes. New York: William Morrow and Company, Inc.

deMan, J.M. (1999). Principles of food chemistry. Gaithersburg, MA: Aspen Publishers Inc.

Potter, N.N., & Hotchkiss, J.H. (1999). Food science. New York: Springer.

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Anonymous asked: Why can't you crowd the mushrooms?

This question reminds me of, and perhaps was inspired by, the movie Julie and Julia, about the famous American chef and cookbook author Julia Child and a discouraged young woman named Julie.  Julie, feeling dissatisfied with her job, sets out to cook all of Julia Child’s recipes over the course of a year, blogging her experiences along the way. In one scene, Julia is sautéing mushrooms while reading advice from Julia Child’s cookbook that says not to “crowd the mushrooms” or else they will not brown correctly.

 I myself am no great mushroom enthusiast. Usually I imagine them as slimy and thick when cooked. However, there’s something whimsical about raw mushrooms. When I saw them in little brown paper bags for sale last Saturday at the farmers market, I couldn’t resist and decided to try my hand at cooking them for the first time. Of course, after I did a little blog research to guarantee that I was using my chemistry skills in the kitchen to perfect them.

Darkone, 8. September 2004

Contrary to what many believe, mushrooms aren’t plants, they’re fungi. Only about 5% of mushrooms are edible, so it’s important to either buy them from a reliable seller or scavenge for mushrooms with the upmost caution, bringing along a book with which to identify mushrooms and someone with experience if you’re new to the hobby. After scavenging for mushrooms in the mountains of New Mexico, I have to say it’s incredibly fun.

Mushroom hunting with cousins:Scott's Camera 9-1-2010 385

When mushrooms are picked or bought, most of their cells are still living, even though they no longer have access to water or nutrients. The mushroom cells continue to absorb oxygen and use it to break down nutrients into energy and water, giving off carbon dioxide in the process. However, the longer this process, called metabolism, continues, the more the mushroom deteriorates. In the supermarket, you might notice that mushrooms are often in foam containers wrapped tightly in plastic. This is to limit the oxygen intake of the mushrooms, thus slowing down its deterioration. Another way of preventing deterioration is by keeping the mushrooms in the refrigerator; the cooling causes the molecules in the mushroom to move more slowly, which in turn slows down the mushrooms’ metabolism.

When a mushroom is heated, its cells die, rendering it incapable of continuing to metabolize nutrients. This is because the membranes of the cells fall apart and therefore can no longer hold water in the cells. The water flows out and the mushroom appears to “sweat”. If the mushrooms are spread apart in the pan and the pan is hot enough, this water will evaporate quickly. Since there is no excess water to suppress the temperature of the mushrooms, they can effectively reach temperatures at which browning occurs. However, if the mushrooms are crowded, the “sweat” from some mushrooms will drip onto others. The water will begin to steam rather than quickly evaporate, boiling the mushroom. This will make the mushroom slimy.

 The browning occurs because mushrooms contain phenols, ring-shaped molecules. When the cell membrane is disrupted by heating, the phenols can mix with an enzyme called polyphenol oxidase. In the presence of oxygen, the two react to create dark pigments called melanins.

Scott's Camera 9-1-2010 392 Dad and I loved the taste of the mushrooms we found ourselves here in the woods!

 

Sources:

Corriher, S.O. . (1997). Cookwise: the hows & whys of successful cooking with over 230 great-tasting recipes. New York: William Morrow and Company, Inc.

deMan, J.M. (1999). Principles of food chemistry. Gaithersburg, MA: Aspen Publishers Inc.

Lam, F. (2010, October 22). How to sear and saute mushrooms. Retrieved from http://www.salon.com/food/francis_lam/2010/10/22/how_to_saute_mushrooms_the_right_way

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I approach cooking from a science angle because I need to understand how things work. If I understand the egg, I can scramble it better. It’s a simple as that.

Alton Brown, interview, Sep. 12, 2002

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© The Exploratorium, www.exploratorium.edu

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The Versatile Egg

Although I’m quite a klutz in the kitchen, there is one food that I’ve mastered. Eggs. Scrambled, over easy, sunny side up, you name it! This summer I even taught myself to flip an egg over without using a spatula, sending it flying though the air…and usually back onto the pan. They can be cooked and eaten by themselves or baked with other ingredients to make all kinds of delicious culinary creations.

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Eggs are useful in cooking because they create emulsions. An emulsion is a mixture of two liquids that normally separate, like oil and water. Recall that when oil and water are vigorously mixed, the oil will form tiny droplets suspended within the water. If this mixture is allowed to sit for a short period of time, the oil will float to the surface and combine with other oil droplets until two separate fluid layers are formed.  Molecules in eggs called lecithin can prevent this by creating emulsions. Lecithin is a type of phospholipid, which is made up of two parts. One end, the head, is attracted to water, and the other end, composed of two tails, is attracted to oil.

Phospholipid_TvanBrussel Ties van Brussel / www.tiesworks.nl

 When mixed with these two substances, the end that is attracted to oil faces inward toward the oil droplet, and the end that is attracted to water faces outward. The lecithin molecules will surround the oil droplet, creating a barrier. If another oil droplet approaches, it will be repelled by the end of the lecithin that faces outward, and it will therefore be unable to combine with the other oil droplet. By keeping oil molecules from associating with each other, they can be properly dispersed in the water.

 532px-Micelle_scheme-en_svg Emmanuel Boutet

 Another property of eggs that allows them to be so versatile is their large amount of protein. A protein is a compound composed of a long chain of molecules called amino acids.  In a raw egg, the proteins are individually curled into balls due to weak bonds linking various parts of their chain. These spherical proteins float around independently in the surrounding water of the egg. The shape of the proteins change when the egg is heated on its own or is mixed with other ingredients.

When heat is applied to the egg, the proteins move around rapidly. They bump into water molecules and other proteins. When this happens, the bonds holding the protein in a spherical shape break. The protein uncurls. The uncurled protein can then bump into other uncurled proteins and form new bonds with them. The proteins begin to interconnect, forming a network that traps the water in the egg.  If the egg is heated too long, this network becomes too extensive, making the egg rubbery.

To visualize this, look at the lines below. The lines on the left represent the proteins in a raw egg. The lines in the center represent denatured proteins. The lines on the left represent coagulated proteins.

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With these explanations, hopefully you have a new appreciation for the simple yet versatile egg!

 Sarah

Corriher, S.O. . (1997). Cookwise: the hows & whys of successful cooking with over 230 great-tasting recipes. New York: William Morrow and Company, Inc.

deMan, J.M. (1999). Principles of food chemistry. Gaithersburg, MA: Aspen Publishers Inc.

Murray, R.K., Granner, D.K., & Mayes, P.A. (2003). Harper’s illustrated biochemistry. New York: McGraw Hill Medical.

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The Science Behind Meat

This weekend, I told my family that I was writing a blog about cooking. My dad asked me to send him a link, to which my mom retorted “since when were you interested in cooking?” She had a point. If my mom isn’t around to cook, my dad will usually opt for a bowl of oatmeal. However, there is one food he can cook and does so marvelously. Meat. So, in honor of my dad, this post will be about the science behind meat!  

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Dad in Aspen

Let’s start by defining meat. Meat is mostly composed of the muscle of the animal being consumed; examples include the muscle of fish, chicken, or my favorite, cattle.  The muscle itself is made mostly of water and protein. Structurally, muscle is composed of big bundles of muscle cells. The individual cells contain strings of protein called filaments that slide past each other as the muscle contracts. To do this, energy is required, which is supplied from a molecule called ATP. ATP is usually created using oxygen, which is carried to the muscle by blood.

Here’s a helpful video describing the process:

After an animal is slaughtered, its heart stops pumping blood. Therefore oxygen cannot be carried to the muscle and be used to create ATP. However, ATP can still be made using sugars in the muscle. This process generates a byproduct called lactic acid, which builds up in the muscle since it cannot be carried away without circulation. The amount of acid buildup affects the quality of the meat. If there is too much acid, the muscle will no longer be able to hold onto the water in its cells, and the meat will be will be watery. Conversely, if there isn’t enough acid buildup, the meat will be dry and tough. This might happen in animals that were working hard before slaughter since they might have already used up the sugar supply in their muscles before death. In this case, most of the lactic acid would be carried away by the blood.

Eventually, the sugars in the muscle of the slaughtered animal are used up, and the proteins in the muscle are left in a permanently contracted state, called rigor mortis. It’s important for this to occur because it affects the texture of the meat, making it less gummy.  If the meat is put in the freezer right after the animal is slaughtered, the contracted proteins will make the meat tough. If the meat is allowed to age, enzymes will break down these contracted proteins, resulting in more tender meat. Therefore, meat processing is very important. Although you, as the consumer, cannot control this, you can buy your meat from trusted brands to increase the likelihood that the processing has been done correctly.

Before meat is cooked, the proteins in the meat are separate from each other and coiled or looped through bonds. When heated, these bonds break and the protein uncoils. When this uncoiled protein bumps into another uncoiled protein, they bind together, or coagulate.  The appearance of the meat changes in part because in uncooked meat, light can travel between the separate proteins. Meanwhile, in cooked meat there is not much space between the coagulated proteins for light to travel, making the meat more opaque and less shiny. Also, when the proteins become coagulated, they shrink since they are now taking up less space. If the meat is cooked for a short period of time, the proteins will trap water between each other as they coagulate, and the meat will be tender. However, the longer the meat is cooked, the more coagulation occurs and the tighter the proteins bind together. The moisture is squeezed out, resulting in tougher meat.  All this comes into play when considering how long you should cook your meat to meet your preferences.

Sarah

Sources:

Corriher, S.O. . (1997). Cookwise: the hows & whys of successful cooking with over 230 great-tasting recipes. New York: William Morrow and Company, Inc.

Murray, R.K., Granner, D.K., & Mayes, P.A. (2003). Harper’s illustrated biochemistry. New York: McGraw Hill Medical.

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No matter how much creativity goes into it, cooking is an art. Or perhaps I should say a craft. It abides by absolute rules, physics, chemistry, etc. and that means that unless you understand the science you cannot reach the art. We’re not talking about painting here. Cooking’s more like engineering. I happen to think that there is great beauty in great engineering.
Chef Alton Brown, interview, Sep. 12, 2002

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Baking Soda vs. Baking Powder

During my first few weeks of living in an apartment, I realized that I could not possibly drink my entire gallon of milk before it expired. There had to be some kind of recipe out there that used copious amounts of milk, right? A quick internet search presented the perfect solution-biscuits! I got to work, adding ingredients like I actually knew what I was doing. Two tablespoons of baking powder, two tablespoons of baking soda, a teaspoon of…oh no. That’s when I noticed my error. There was no baking soda in the recipe. I’d already added in all the other ingredients, so there was no turning back. I decided to put my ruined dough in the oven, figuring I might as well see what it ended up like rather than throw it all away. They turned out terribly bitter. After one bite, I threw my biscuit in the garbage. My roommates, however, thought they tasted great and finished off the batch within a couple days. This I do not understand. To discover why my biscuits tasted so strange, I did some research to discover the differences between baking powder and baking soda.

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Baking powders and baking sodas are both leavening agents, meaning that they add gas to dough.  As I mentioned in my last post, the proteins in dough form structures during mixing that trap gas. During the baking process, the gas released from the leavening agent causes the dough to expand as it is heated. The final product will be lighter and softer due to the air pockets left behind by the gases.

There are two main types of leavening agents. Biological leavening agents are actually microorganisms that release carbon dioxide; an example is yeast. Baking soda and baking powder fall under the category of chemical leaveners, which combine with acidic ingredients to release carbon dioxide. Chemical leaveners release carbon dioxide more quickly than biological leavening agents, so they’re often used in cookies, quick cakes, and quick breads. They also do not release some of the flavors released through the fermentation of yeast.

Baking soda is composed of sodium bicarbonate (NaHCO3), a base. It’s a fine white powder actually made of tiny crystals that was first introduced into the culinary world in 1846 in New York.  When combined with acid at baking temperatures, the sodium bicarbonate breaks down into carbon dioxide, sodium carbonate, water. Examples of acids include vinegar and buttermilk.

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Note that sodium bicarbonate is the only ingredient listed for the baking soda

Baking powder usually is a mixture of baking soda and an acid, and a starch. The starch is usually corn starch but sometimes potato starch, and its purpose is to soak up moisture and increase shelf life. The acids can be slow or fast acting. The fast-acting acid forms carbon dioxide at room temperature as it reacts with moisture but the slow- acting acid does not do so until heated in the oven.  Double-acting baking powder contains both. Examples of acids found in baking powder are cream of tartar and alum. Essentially, baking powder combines with liquid to create the same reaction as baking soda.

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Note that the baking powder includes not only sodium bicarbonate, but other ingredients, including an acid

Baking soda can be substituted for baking powder. This can be done by replacing the amount of baking powder with a forth of the amount with baking soda, a forth of the amount with cornstarch, and half the amount with cream of tartar. However, baking powder cannot be substituted for baking soda. This is because, as stated earlier, the baking powder contains acid, and if added, it will likely alter the flavor and texture of the food.

With all this, I can conclude why adding the extra baking soda ruined my biscuits.  The acidic components of the recipe, such as the milk and the shortening, contribute to its flavor, and with all the baking soda I added, it had been completely neutralized, leaving the bitter taste of the basic baking soda.

I have learned my lesson. Baking soda and baking powder can’t be swapped or doubled with no consequences! And if you want to give my failed biscuit recipe a shot, you can find it here: http://allrecipes.com//Recipe/jps-big-daddy-biscuits/Detail.aspx

Happy baking!

Sarah

Sources:

Matz, S. (1992). Bakery technology and engineering. New York: Van Nostrand Reinhold/Avi

Plyer, E.J., & Gordon, L.A. (2009). Baking science and technology. Kansas City, Mo.: Sosland Publishing Co.

Church & Dwight Co. Inc, . (1999). Church and dwight. Retrieved from http://www.churchdwight.com/Company/corp_history.asp

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Cuisine is both an art and a science: it is an art when it strives to bring about the realization of the true and the beautiful, called le bon (the good) in the order of culinary ideas. As a science, it respects chemistry, physics and natural history. Its axioms are called aphorisms, its theorems recipes, and its philosophy gastronomy.
Lucien Tendret (1825-1896) ‘La Table au pays de Brillant-Savarin’

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Welcome Chefs!

Hello everyone, and welcome to my blog, The Science of Cooking!

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Baking with my bird Trouble

My name is Sarah, and I am a third year Nutrition Science major who loves food!  Preparing food, however, is another story.  Recently, I moved out of the dorms and into an apartment with a place where the magic happens, the kitchen.  I wasn’t intimidated at first. In fact, grocery shopping on my own for the first time was actually quite exciting! However, after the first week of school, I had burned my fried zucchini repeatedly  and failed to make a proper white sauce three times, not to mention that half the produce in my refrigerator went bad before I could even use it. Suddenly, cooking didn’t seem so fun after all, and I converted to the mac-and-cheese diet.

Despite this, all hope was not lost, thanks to my food chemistry class (a must-take for all true gourmands). By learning about the properties of foods, I began to realize that cooking does not require some elusive set of superpowers. It’s science, chemistry.  A cookbook is like a lab manual, and if proper techniques are followed, the ingredients will react in predictable ways. For instance, when you knead bread, the proteins in the dough form structures that create small air pockets. These trap carbon dioxide created by yeast, and the bread rises. Knead too little and the proteins won’t form enough structure. Kneed too much and the air pockets will be tiny, making the bread too dense. There was something to this. There was potential to learn.

And so I invite you to join me as I puruse books, websites, and articles to master the art of cooking by understanding the science of cooking. With a little research, perhaps I can transform from rhinocerous in the kitchen to chef extraordinaire! Eat, drink, and be merry in the kitchen!

Sarah