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Laboratory Exercise

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Laboratory Exercise


Laboratory Exercise


Baking the Best Cookie (whatever kind you think is best)!


The search for the best cookie. For some, this is an unattainable goal. What is the perfect cookie? Soft or crispy; chewy or crisp; caked and fluffy or dense; brown and tasty or moist and light? Too many options! How do like your cookie prepared? The key to any baking is precision in measuring. You can understand this by reading a small fraction of the incredible amount of information available on measuring by volume (cups, tablespoons…) vs mass (everything measured on a scale). For this laboratory experience we will avoid such controversy and focus on the science of what goes into a cookie. Flour, sugar, butter and the source of moisture (water) all impact the final characteristics of a cookie. Review the infographic in your book on cookies and each of the components of a cookie found in Chapter 10, Breads, Cakes and Dough to read about the details of each component.


Inside a baking cookie is a pretty busy place. As a cookie bakes a few things happen. Heat will melt the fat causing the cookie to spread. Water will evaporate creating gas pockets giving rise to the cookie and dry out cookie (especially at the edges). Egg and flour proteins will denature as the cookie heats cross-linking trapping the expanding gasses. Starches will hold water by hydrogen bonding and along with proteins set giving the cookie its final shape. Leavening agents will generate gasses that, along with the water gasses will be trapped by proteins and starches giving rise to the dough. Sugar will caramelize and mix with proteins to produce Maillard brown flavors. The ratio of fats, proteins, sugars and liquid all impact each of these steps. The final characteristics of a cookie depends on the types of each component (fat, sugar, protein and liquid) are added or prepared. Carefully consider what each component brings to the party and how they interact as we create a hypothesis to experiment with baking the perfect cookie.


Once you understand the biology and chemistry of each of the components of a cookie and how they interact and react you can begin to make choices in your cookie experiment. Review the information in the table below and using the information in our book begin to build your hypothesis to make the BEST cookie.

FatsButter (melted,creamed, whipped orsolid)ShorteningMargarineLeavening agent Baking soda vs baking powder – do you need to add an extra ingredient?LiquidWater, eggs, milk orcreamSugarBrown SugarWhite SugarMolassesHoneyCorn Syrup
FlourAll PurposeBreadCakeEgg – whites and yolks. Each provides a different chemical characteristic to a cookieMixing, kneading – forming cross-linked gluten will impact the kind of cookie you make. How?Resting the dough -Check out HaroldMcGee and KengiLopez-Alt for info.
Ratios – we will stick to the same masses & volumes for this experiment but changing the amounts and ratios of each component can have a real impact on the finalcookieTemperatures and duration – another set of important factors in making a cookie.

Special Notes:

Fat is cookie baking.

You choose to change the type of fat that you will use. If you choose this variable, you can choose butter or butter flavored shortening. In making this decision you should consider how the different properties of these fats might affect the outcome.

· Butter is approximately 80% fat and 20% water, and it melts at a lower temperature than shortening.

· Shortening is 100% fat and therefore melts at a higher temperature.

· Here are some facts about shortening from the manufacturer:

· 50% Less saturated Fat than Butter.

· Crisco: 3g Saturated Fat per tablespoon

· Butter: 7g Saturated Fat per tablespoon ▪ Crisco contains 12g total fat per serving.

Flour in cookie baking.

The protein in the flour absorbs the liquid forming gluten. Because of this, a higher protein flour gives a drier, flatter, crisper cookie that holds together better while a low protein flour gives a softer, tender, puffier cookie as the unabsorbed liquid turns to steam puffs the cookie.

We will rank the baked cookies in terms of spread vs. puff, tenderness and color.

Mixing in cookie baking.

Mixing fat with flour limits the gluten formation since gluten formation requires water. We also know that fat is hydrophobic and non-polar, hence mixing fat with flour coats the starch granules in fat and limits the access to water.

Your part in cookie baking.

Read the background information and instructions for this laboratory including the infographics on cookies and chapter 10. This laboratory exercise requires that you work independently for baking, but that you coordinate with other members of your class to test several variables. Each student should focus on one variable. Each student should make the control cookies for taste comparisons. Once the class has decided on the variables to test (in the discussion forum) then you can prepare a hypothesis for each tested variable and make a prediction for the hypothesis.

Pre-Laboratory Questions and Concepts:

1. What is the specific chemical role for sugar, leavening reagent, proteins and fats in baking cookies?

2. What are the main components of flour? What is the difference between each type of flour listed in this handout?

3. There are several types of sugars presented in this handout. What are the differences? What do you predict will be the impact of these sugars?

4. Egg yolks add an emulsifying agent to cookies. What is the emulsifier? What does this emulsifier do to the final cookie?

Process of Sciences:

You will be making cookies using the control recipe. Then working with the other students in the class each of you will be making a change to ONE variable. The questions you have just answered should help you think about the different experiments you will be doing in this laboratory exercise. At this time, just as you have seen in the previous laboratory exercises you should create:

1. A key question being investigated for making the best cookie.

2. A hypothesis or proposed answer to the question asked based on your changed recipe.

3. A prediction for the outcome of the experiment based upon your hypotheses you developed. The prediction should written as an if/then statement and be specific to the measurements being made.

4. An explanation of your reasoning for each of your hypotheses and predictions.

Exercise 9. Baking the Best Cookie.

Basic (Control) Recipe

⅔ tbsp (2 tsp) butter (Cut a one tbsp square into thirds)¼ cup + 1 tbsp white sugar
½ cup flour: All-purpose bleached flower⅓ of an egg (1 tbsp beaten egg)
¼ tsp salt1 tsp vanilla
¼ tsp baking powder⅓ cup chocolate chips
3 tbsp shortening.

Common Variable Options for the Recipe

Butter, Margarine, I Can’t Believe Its Not ButterWhite, brown sugar, molasses, honey, corn syrup
All-purpose bleached flower, Cake Flower, Bread FlowerEggs, heavy cream, whole milk
baking powder, baking soda, tartaric acidchocolate chips
Plane and butter flavored shortening.Walnuts


1. Preheat the oven to 375°F.

2. Prepare the control batter as follows: Sift together the flour, salt and baking powder in a mediummixing bowl. This means combine the dry ingredients into the wire mesh strainer while holding it over your mixing bowl. Gently stir the dry ingredients until all have sifted through.

3. Using a mixer (hand or electric), cream together the fat and sugar in a large bowl until light and fluffy.

4. Add the liquid or egg and beat thoroughly, scraping down the sides of the bowl with a rubber spatula.

5. Beat in the vanilla.

6. On low speed, gradually add the dry ingredients until thoroughly combined.

Scrape the sides of the bowl down with a rubber spatula.

7. Add the chocolate chips, beat 5 seconds on low. Use a rubber spatula to finish mixing well.

8. Cut several pieces of parchment paper to fit the baking sheet – make sure the parchment lays flat

9. Using a tablespoon, drop slightly heaped tablespoons of batter 2 inches apart onto the parchment paper.

10. Repeat for the rest of your cookies. If the entire batch of cookies does not fit on one baking sheet, you can bake in shifts. If the dough begins to warm too much, you can place the bowl of batter inside another bowl of ice.

11. Bake the cookies for 10-12 minutes, or until the edges just begin to brown.

12. When baked, carefully slide the parchment paper onto a cooling rack, and allow cookies to cool completely.

13. Repeat with the variable recipe.

The Cookie Comparison

You will post your results to the Discussion forum so that everyone can work together to analyze the products. Compare cookies among the class considering spread vs. puff, tenderness and color. Rate spread and puff with a ruler. Rate tenderness on a 1=10 scale with 1 being flat and rock hard. Rate color from 1-10 with 1 being raw, unbaked color and 10 being fully burned black. Rate taste from 1 – 10 with 1 being inedible and 10 being the best cookie ever.

Conclusions and Discussion:

1. Report on at least 5 of the variables chosen by your peers, and compare to the control cookie. Report the variables, hypotheses and predictions. Organize and present the hypotheses in your report.

2. Create a table and record the width (average spread) height (average puff in the middle of the cookie) the tenderness (range from 1 (crisp) to 10 (very flexible/tender) and color (range 1-10; 1= dough colored light & 10 = dark brown/black) and rate the taste from 1 – 10 with 1 being inedible and 10 being the best cookie ever. Do this for YOUR cookie and post in the Discussion forum. Then add to your table with at least FOUR other variables in your final report.

3. Summarize the impact of each variable on the baked cookie results prepared in question 2. Include the impact in terms of your hypothesis and prediction.

4. For EACH variable that you choose, detail how that variable affected the cookie in the Results. Then, in the Discussion, detail the chemistry behind each kind of cookie.

Process of Science Questions and Conclusions:

Earlier you created key questions, hypotheses, predictions, and explanations for this prediction for each of the experiments in this laboratory exercise.

Based upon your data and the questions you have answered related to this exercise you should be able to complete the process of science questions and conclusions.

Answer the following questions.

1. Did your data support or falsify your hypothesis?

2. How did you come to this conclusion?

3. Did these results change your thinking about this topic? How?

4. What changes would you make to your hypothesis based on this new data?

5. What changes would you make to the experiments to better clarify your results?


1. http://sweets.seriouseats.com/2013/12/the-food-lab-the-best-chocolate-chip-cookies.html

2. Bakewise – Shirley Corriher and Keys to Good Cooking: A guide to making the best of foods and recipes. Harold McGee




500 word essay…

Do the control cookie recipe as well as their selected variable ingredient. Once you have prepared the cookies, measure the spread and puff, and rate the tenderness, color and taste. You may report this using a video or pictures (or both). You should also create and include a table with these data included on it. (You will then expand this table with other variables in your final report). You should also be clear about why you gave the ratings that you gave. As you prepare to write your report you will want to compile the data for at least FIVE variables together (one variable should be your own).

My Results

My sugar cookie experiment is on the difference between baking soda and baking powder. The baking powder sugar cookies came out round and fluffy, but short. The baking soda came out more flat, and round. The color on both are the same(light brown). To me the cookies that taste the best are the baking powdered cookies. The baking powder is more of a cakey texture. 

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